English Instruction Book No. 25
Copyright © 1957 Kelvin Diesels PLC

Model "P"

Operating Instructions


Maintenance Manual


    Operating Principle of Engine.
    Lubricating Oil.
    Stern tube.
    Engine Foundation.
    Fuel Tanks.
    Exhaust Connection.
    Installation Sheets.
    300 Hours.
    1500 Hours.
    3000 Hours.
    Section A--Fuel System
        1. Feed Pump.
        2. Fuel Filter.
        3. Fuel Pump.
        4. Injector Assembly.
    Section B--Lubrication System
        1. Crankcase Pump.
        2. Oil Strainer.
        3. Oil Filter.
        4. Adjustment of Oil Pressure.
        5. Oil Pump.
        6. Dismantling & Assembling The Oil Pump.
    Section C--Cooling Water System
        1. Sea Cock.
        2. Water Pump.
        3. Water Spaces.
        4. Water Bushes.
    Section D--Exhaust System
    Section E--Cylinder Head
        1. Rocker Cover.
        2. Rocker Assembly.
        3. Valve Clearance.
        4. Cylinder Head.
        5. Decarbonising.
        6. Valves and Springs.
    Section F--Reverse Gear
    Section G--Timing Gears and Camshaft
    Section H--flywheel, Starting Mechanism and End Cover
        1. Flywheel and Lower Starting Wheel.
        2. End Cover.
    Section I--Pistons and Connecting Rods
        1. Removal.
        2. Inspection.
        3. Assembly.
        4. Oversize Pistons.
    Section J--Crankcase
        1. Cylinder Liners.
        2. Crankshaft.
    Engine will not start.
    Engine Starts but fires unevenly and soon stops, or does not gain full speed.
    Dirty exhaust.
    Knocking sound in engine.
    Excessive Lubricating Oil Consumption.
    Engine overheating.
    Boat loosing speed.
    Reverse Gear.



    The Kelvin Model "P" is a Diesel engine working on the four stroke cycle, with direct injection of the fuel into a specially shaped chamber in the crown of the piston. The shape of this chamber, in combination with the design of the air inlet port produces a swirl in the air charge. Mixing of fuel and air is assisted by the very fine atomization of the fuel as it emerges from the three holes in the tip of the nozzle. This intimate mixing of fuel and air ensures complete combustion of the fuel. There is always a large excess of air present in the combustion chamber even when the maximum permissible amount of fuel is being injected, and this whole charge of air is drawn into the cylinder for every cycle. The power developed by the engine is controlled by varying only the amount of fuel injected into the cylinder.

    In the four stroke cycle each cylinder completes one combustion cycle every two revolutions (i.e. four strokes of the piston). Each stroke has a function and they can be briefly described as follows, the cycle starting with the piston at the top of the cylinder :-

1. Suction stroke--engine draws in air only.

2. Compression stroke--engine compresses air in cylinder.

3. Power stroke--piston is forced down cylinder by expansion of gases following combustion of the fuel charge injected at the
end of the compression stroke.

4. Exhaust stroke--engine expels gases from cylinder.

    Thus it is only on the 3rd stroke that power is developed and on the remaining three strokes power must be applied to drive the piston. This power comes from (a) another cylinder or cylinders, (b) the flywheel, (c) when starting, an outside source.


    When ordering spares from us, please quote the Engine Model and Engine Number from the name plate, as well as the exact name or code for the part. This will ensure that we supply the correct parts for your engine.

    When ordering spares for the Fuel Pump, Governor, injector Assembly, Fuel Filter, Feed Pump, Oil Filter or any other proprietary part, please quote the maker's reference numbers from the parts concerned.

    When fitting a spare part as a replacement for a worn item, transfer any numbered mark (usually the cylinder number) from the old to the new part. These marks are made by us during building of the engine in order to ensure that the operator can replace parts in their correct position.

    The crankshaft bearings on this engine are precision machined and should on no account be scraped or filed in any way. The same applies to the seating for the bearings. If the seating are interfered with, it will be impossible to fit replacement bearings when these become necessary.

    Bushes fitted in various parts of the engine are also pre finished. They are steel backed and lined with a thin layer of bronze and require only to be pressed into place.


    We make improvements from time to time and, where possible, we make them applicable to engines already dispatched. If you wish to know whether any improvements have been added since your engine was made, send us a note of the engine number.


    The engines are tested at our works on Gas Oil and will run on any of the fuels sold by this general title. The fuel used should comply in general with British Standard 209: 1947 Class A and be of an equivalent quality to that supplied for road vehicle use.


    The lubrication of an engine is an important factor governing the length of its life. Use only good quality oil from reliable makers. For normal temperate climates the viscosity of the oil should be SAE 20 or 20W, the latter being of advantage if cold weather (about freezing point) is being experienced. For tropical use, oil of SAE 30 viscosity is more suitable.

    The engine will run satisfactorily on ordinary straight mineral oils, but detergent or heavy-duty oils can be used with safety. Detergent oils will result in a cleaner engine as the sludge is held in suspension and is drained along with the oil.


    Before laying up an engine for the winter, it is important to remove any salt dried on to it, as this draws damp and causes excessive rusting. This salt can be removed by washing the engine with hot water.
Drain all the water from the engine and pipes. The water drain point is on the fuel pump side of the crankcase. Pour some lubricating oil into each cylinder through the injector hole and turn the engine by hand. Grease everything not protected by paint.


    Damage due to rust is not covered by the guarantee. In open boats the engine must be protected by a box, the top of which should be watertight. if bilge water or salt spray is allowed to reach the flywheel damage to the engine is certain.
    The fixing of an engine in a boat should be carried out in the following order:-
1. Stern tube.     2. Shafting.     3. Engine.
    The final alignment of the engine to the shaft should be deferred until the boat is afloat. Levelling washers are provided with the equipment.
    The maximum movement of the propeller shaft from "Ahead " to "Astern" is 1/2". Kelvin equipment is, of course, suitable for this movement, but if the shafting and stern tube were not supplied by us, please check that this movement is possible. When installing "Kelvin" sterner, please note carefully the clearance which must be allowed between the propeller boss and the outer end of the propeller shaft bush.
    The bush in the bearing fitted to the outer end of the stern tube requires through circulation of water. This water enters by two small pipes projecting from each side of the stern tube outer bearing and the stern tube must be trimmed down to bring the pipes into the streamline. Do not grease the shaft before inserting it. The packing in the gland at the inner end of the stern tube should be impregnated with graphite and only a minimum of grease, As the graphite is dissolved out of the packing in time, it is desirable to renew the packing once a year.
    As standard equipment, we supply bronze propeller shafting and steel intermediate shafting with a grease lubricated intermediate shaft bearing. The design of our shaft couplings is such that the shafts can be cut to exact length by a hand saw if necessary.
The shaft coupling bolts must be very tight. If once they slip both coupling and shaft become torn and ruined. All parts of the shaft coupling should be painted before being assembled. If the shaft runs out of truth, it is probably due to unequal tightening of the shaft coupling bolts. Hold a pencil to the running shaft, and tighten the bolts at the side marked by the pencil.
    Propeller shaft vibration can be caused by (a) lack of clearance between propeller and woodwork, (b) propeller blade bent, (c) shaft out of truth, (d) shaft bearing slack.
The shaft bearing (if fitted) should be mounted on a hardwood bearer and be accessible for lubrication. The greaser should be given 1/2 turn daily and refilled when necessary. Slackness of the shaft bearing can be corrected by filing the face of the bottom half.
    This engine is designed to rest on either fore and aft or transverse bearers. In wooden vessels, the bearers should be of hardwood and in steel vessels, of adequately gusseted sections, with a 1/2" thick hardwood packing between the engine foot and the steel section. Foundation Bolts (1/2" dia.) for wood bearers are supplied in the equipment. These are screwed into 1/2" dia. x 2 1/2" deep holes in the bearers by means of double nuts locked to the outer screw thread, and must be driven very tight. Eight Levelling Washers are supplied with the equipment and one, at least, should be fitted below each foot.
    On no account should tanks or pipes for Diesel Fuel be galvanized internally. We recommend customers to use our tanks. If the tanks are not supplied by us, damage to the fuel pump caused by water, rust or zinc sediment is not covered by our guarantee. Our tanks are fitted with an ample sized sediment trap which should be drained at least once a month.
    The bottom of the tank must be at least 15" above the shaft for gravity feed. If the tank is fitted at the stern of the boat, a margin of height must be allowed for sinking of the stern when under.
    Where the tanks are too low to allow the fuel to be fed by gravity, order a feed pump as additional equipment for the engine.
    Our standard propellers are made from high tensile bronze.
    If you think the propeller inefficient, this may be due to (a) lack of clearance between propeller and woodwork--increase the aperture where possible, (b) stem post too clumsy--reduce it as much as possible, (c) rudder post too thick--reduce or abolish it, (d) diameter or pitch of propeller not suitable.
    If you consider the propeller unsuitable, report to us the length, beam and draft of the boat, together with the boat and engine speeds.
    The propeller should be removed with a heavy hammer, a light one damages the propeller without removing it. Secure the nuts with a turn of monel wire through the hole in the end of the shaft.
    The standard silencer is of the wet type, in which engine cooling water and exhaust gases are mixed, giving a cool silencer and exhaust pipe. The exhaust pipe is of rubber and is thus easily installed.
    The exhaust must discharge slightly above sea level and the silencer must be above the level of the point of discharge even when list and rolling are taken into consideration. There is no objection to a downward dip in the pipe, but no part of the pipe should be above the silencer. The best arrangement is to give the pipe a gradual fall throughout its length from silencer to point of discharge. A dry exhaust silencer and steel piping can also be supplied.
    We have available for the assistance of customers the following installation Sheets, which give details of some of the equipment we can supply to help in the building of a satisfactory installation.
No.  6
Deck Control.
No.  12/13
No.  18/19
Horizontal and Vertical Tanks.
No.  27
Kelvin Engine Bearer Bolts.
No.  28/29
No.  31
Engine Boxes.

These Sheets are available on request.


1. Fill fuel tanks and turn on fuel cocks.
2. Unscrew Oil Filler Cap and pour in lubricating oil until Dip Rod shows "Full."
3. Lubricate the Starting Shaft Bearings and the starting mechanism behind the flywheel.

4. Remove the breather cover on the top of the gearbox and pour in the correct quantity (1/2 pint or .28 litre)  of engine oil. The capacity of the oil can in the tool kit is 1/2 pt. and it should be used to measure  accurately the quantity of oil poured into the Reverse Gear. Put reverse gear in the neutral position,  i.e. with the knob of the Control Wheel pointing downwards. The word "NEUTRAL" is stamped  on the control wheel. This mark should be at the top to obtain the neutral position

5. Vent air out of fuel system.
    The low pressure side of the system is dealt with as described in paragraph (a) or (b).
    (a) If the system is gravity fed, the bleed screws on the fuel filter and fuel pump should be loosened a few turns. In due course, the fuel will flow clear of air, and the screws can then be tightened.
     (b) In a feed pump system, fuel will not flow to the filter and pump without the priming lever on the feed pump being operated continuously.
    The high pressure side of the fuel system must now be vented. Loosen the coupling nuts between the steel injector pipes and the Nozzle Holders. Set the Governor Control Lever at its mid position and press the button on the starting device fitted to the fuel. pump. With the engine decompressed (i.e. Decompression Lever vertical), turn the Starting Handle. until fuel flows in spurts from the pipes. Tighten the coupling nuts and turn the engine a few revolutions until the injectors are heard to make a characteristic "creaking" noise, showing that, fuel is being injected into the cylinders.
6. Check the level of the lubricating oil on the dipstick after having turned the engine over for some time in
step 5. The filter will have filled with oil and probably reduced the level below the "Full " mark.
7. Turn the sea cock to the open position. In the case of a new engine, the finger pin for the cock will be found in the tool kit. Hang it on a nail near the sea cock. Loosen the coupling nut at the top of the water pump, i.e. the outlet side.
8. Check that the controls are in the positions of stage 5, i.e. engine decompressed, speed control midway, button on starting device pressed. Turn the starting handle smartly with one hand and after 2 or 3 revolutions move the decompression lever to the horizontal position, while continuing to turn the handle. With the assistance of the heavy flywheel, the engine will go over full compression and should start easily.
9. When the engine starts, reduce the speed to fast idling. Check oil pressure.
10. When water appears at the outlet from the water pump, tighten the coupling nut.


1. Do not allow the fuel tank to run dry. If this happens, the air must be vented from the whole fuel system before the engine can be re-started (P.9). if the fuel tanks need to be filled do so before stopping work for the night. This gives water and sediment a chance to settle before the engine starts running again.
2. Manipulating the clutches of the reverse gear without first slowing down the engine causes excessive wear. When using the reverse gear, engage the clutches firmly, but do not use excessive force.
3. In dirty waters, where sand, weed, jellyfish or refuse may foul the cooling system, special care must be taken to keep the water inlet clean. Even a temporary stoppage of the cooling water may cause overheating and subsequent damage.
    If the Water intake is blocked, a rod of about 3/8" diameter can be pushed through from inside the boat, with the sea cock in the open position. This should clear the obstruction from the Water Intake, but care must be taken not to allow excessive water into the boat.
4. A tool kit accompanies each engine. When dispatched from our works, it is closed with a lead seal. If delivered with the seal broken, the contents should be checked against the tool list on Page 1201 of the catalogue.
5. The button on the starting device on the fuel pump should never be pressed while the engine is running. Damage to the engine may result from mis-use of this device.
    Do not alter the setting of the maximum speed stop on the governor. This is set and sealed before the engine leaves our works. If the engine does not reach its rated speed, it is due to overloading through the use of an incorrect propeller.
6. To stop the engine push the Governor Control Lever firmly past the idling position against the spring. This cuts off the delivery of fuel to the cylinders.


    The maintenance intervals given below are recommended where an engine is in daily use. For engines used only occasionally, "Daily Maintenance" would be necessary on each occasion that the engine was used. A complete overhaul should be carried out at least once in five years, no matter how little the engine has run.

    Keep your engine clean. Use only cotton waste this is more suitable than old cloth. For further information regarding the dismantling and assembling of parts, see under the appropriate paragraphs in "General Maintenance instructions."


1. Check fuel in tanks.

2. Check level of lubricating oil in sump and top up to "Full" mark on Dip Rod.

3. Clean Sea Cock Strainer (P.20).

4. Screw down water pump and propeller shaft bearing grease cups by 1/2 turn.

5. Oil Starting Shaft, Lower Starting Wheel and Pawls.

EVERY 300 HOURS (or up to 3 months).

1. Check Fuel System.

(a) Remove and clean Fuel Filter Bowl (P.15).

(b) Drain sediment from sumps of fuel tanks.

(c) Clean gauze strainer in Feed Pump, if fitted (P.14).

2. Change Engine and Reverse Gear Lubricating Oil. (These operations are best carried out when the oil is hot.)

(a) Pump out all lubricating oil from engine sump (P.18).

(b) Remove Oil Strainer from Crankcase and brush with fuel oil to wash away sediment (P.18). Do not wipe the inside  of the
Crankcase with cloth or cotton waste. Use only a brush for this task.

(c) Remove and clean out the Oil Filter Bowl. Throw away the old Oil Filter Element and fit a new one.

(d) Replace Oil Strainer and refill engine with the correct grade of lubricating oil.

(e) Drain oil from Reverse Gear and refill with 1/2 pint (.28 litre) of clean engine oil (P.24).

3. Check oil level in Governor. The oil level plug is on the end of the governor case.

4. Clean Air Silencer by washing in fuel oil or kerosene. Allow it to dry before replacing on engine.

5. Check and adjust valve clearance if necessary.

6. Refill grease cups on Water Pump and Propeller Shaft Bearing.

EVERY 1500 HOURS (or up to 2 years).

1. Decarbonise the engine (P.23).

2. If after overhauling Cylinder Head (P.21) compression is still good, do not dismantle further. If compression is poor, remove big end bolts, scrape carbon from top of cylinder bore and take out pistons and connecting rods through tops of cylinders. Clean the pistons and rings, and replace them in cylinder. Fit the large end bearing, and tighten connecting rod bolts (P.30).

3. Remove all water pipes, clean out water passage into cylinder block. Renew all water joints.

4. Clean out air inlet elbows and exhaust manifold and pipe. Inspect silencer.

EVERY 3000 HOURS (or up to 5 years).

    Dismantle engine completely and overhaul, renewing parts as necessary. This operation will require the engine to be removed from the boat. It can be partially dismantled before being lifted, the heaviest unit weighing about 150 lbs.



    Note.--After having opened any part of the fuel system, it will be necessary to ensure that all air has been removed before trying to start the engine. This is done by venting the system as described on page 9.
    The Feed Pump is mechanically operated by an eccentric on the camshaft. A gauze filter is incorporated to prevent coarse dirt from getting under the valves of the feed pump.
Cleaning the Filter Gauze.
    The filter gauze should be examined every month, or say 300 hours, and cleaned if necessary. To examine the gauze remove the dome cover after unscrewing the cover retaining screw. The filter gauze may then be lifted from its seating. Clean out any sediment which may have gathered in the bowl. Clean the filter gauze by light brushing in fuel oil. Renew the cork joint under the cover if it is found to be hard or broken. Ensure that, on refitting the cover, the fibre washer is in place under the head of the cover screw. Do not tighten the cover screw more than necessary to make an oil tight joint. Check the fuel pipe unions for tightness.
Testing while on the engine.
    On operating the priming lever at the side of the pump with the fuel pipe disconnected at the fuel filter, a well defined spurt of fuel should be seen every time the lever is released.
Dismantling and Maintenance of Feed Pump.
    Remove pump from engine, mark the flanges of the top and bottom parts of the pump for guidance when assembling. Take off cover, remove 5 screws and separate the two main castings. Note the position of the tab on the fabric diaphragm relative to the body. To remove diaphragm, press downwards and turn diaphragm 1/4 turn clockwise. Do not attempt to separate the layers of fabric of the diaphragm from the washers and pull rod. This is a permanent assembly. Renew the diaphragm assembly if it shows any hardness or cracking.
    If the valves are removed great care should be taken to keep them clean. Wash in paraffin or fuel oil before replacing and renew valves and springs at any sign of wear.
    To fit the diaphragm place it on the face of the body with the pull rod downwards, through the spring, and the tab towards the engine mounting flange. Press downwards to compress the spring and, engaging the slots of the pull rod in the slotted hole in the lever, move the tab 1/4 turn clockwise, thus bringing holes in diaphragm into line with those on body.
    Hold rocker arm of pump at its full travel away from the pump body, replace upper chamber and tighten screws.
Refitting Feed Pump to Engine.
    Use only the correct thickness of joint and ensure that rocker arm is correctly positioned on the front of the eccentric. After re-fitting to the engine, test the pump by rotating the engine. A spurt of fuel should appear at the loosened fuel filter in let connection.
    The Fuel Filter is connected into the fuel system between the Feed Pump and the Fuel Pump. If no Feed Pump is fitted, the fuel flows directly from the tank to the Filter. The filter element is of the paper type, which is replaced as a unit when its life is finished. With fuel of normal cleanliness its life should be more than the interval between major overhauls.
Cleaning the Filter Bowl.
    Unscrew the large knurled nut and remove the bowl. Wash in fuel oil and replace. No tools should be used on the knurled ring. Finger pressure only is required.
Changing the Filter Element.
    Remove the bowl. The element is retained by a screw inserted from the bottom. Remove the screw, take off the large metal washer, fit these parts to the new element, and re-assemble.
    The Fuel Pump is of the conventional type, mounted by a 3 bolt flange on the forward face of the timing wheel case. The Governor is built on to the fuel pump, and pump and governor are to be treated as a single unit. Fitted to the Fuel Pump is a device to assist in starting. This operates only when, the button is pressed. The setting of the maximum speed stop is determined at the factory, and must not be altered. The idling stop is adjustable.
    When the Governor Control Lever is pushed past the idling position, the stop lever on the fuel pump is moved by a linkage, cutting off the delivery of fuel to the cylinders and thus stopping the engine.
Repairs to Fuel Pump.
    Dismantling and overhauling of a fuel injection pump should not be lightly undertaken, as only specially trained mechanics can be expected to carry it out successfully, using the special tools available from the manufacturer of the fuel pump.
    In an emergency, it is suggested that all that can be undertaken by the normal operator is the replacement of broken plunger springs, faulty camshaft bearings, or faulty delivery valves and seats. Instruction books giving full information on these points are available on request from The Bergius Company, or from any agent or branch of the pump manufacturer. Full servicing facilities for all fuel injection equipment are also available from the same sources.
Removal of Fuel Pump and Governor Assembly.
    Disconnect water pipes at the Water Pump. Take off 3 nuts holding Water Pump Plate and remove Water Pump and Plate.
    Carefully remove two set screws and lock washers holding Water Pump Driving Dog to Fuel Pump Wheel, and take out the. Driving Dog.
    Using a box spanner loosen the Fuel Pump Camshaft Nut and remove the nut and lock washer.
    Take off the Fuel Injection Pipes and disconnect the Governor Control Rod.
    Remove the three nuts on the fuel pump flange and withdraw the pump and governor assembly, leaving the Fuel Pump Wheel in position in the Timing Wheel Case.
Refitting the Fuel Pump and Governor Assembly.
    Set the key on the fuel pump camshaft so that its position corresponds as nearly as possible with the key way in the Fuel Pump Wheel.
    Fit fuel pump camshaft into wheel and at the same time enter the studs on the Timing Wheel Case into the flange of the fuel pump. Tighten the nut and lock washer on the camshaft and fit the nuts and plain washers loosely on the studs at the flange.
    Set the injection timing marks on the flange and on the Timing Wheel Case so that they are identically opposite each other and finally tighten the nuts on the flange.
    Replace Water Pump and pipes.
Fitting a New Fuel Pump and Governor Assembly.
    In this case, the timing mark will not be on the new fuel pump flange and the injection timing must be set by spill cut off as follows:- Turn the engine till the line at the timing mark (lNJ) on the rim of the flywheel is in line with the mark on the machined face at the end of the crankcase on the centre line of the engine, and with No. 2 or 4 cylinder (nearest reverse gear) at the end of its compression stroke, i.e. both valves closed, piston near top of stroke. Fit Fuel Pump to engine as in previous section, without finally tightening the flange nuts. Vent air from system, then turn off the fuel cock if it is a gravity fed system.
    Unscrew the delivery valve holder and lift out the delivery valve spring and delivery valve, laying these aside in a clean and secure place. Replace the delivery valve holder lightly in the pump.
    Turn on the fuel cock or, if a feed pump is fitted, give the hand priming lever a few strokes. If fuel flows from the delivery valve holder, the pump requires to be advanced by rotating it a few degrees anticlockwise, when viewed from the governor end. If no fuel flows, the pump requires to be retarded by rotating it a few degrees clockwise, when viewed from the governor end.
    The setting is correct when only the finest trace of leakage from the delivery valve holder can be seen. When this position is found, mark the flange of the new Fuel Pump to coincide with the mark on the Timing Wheel Case, and replace delivery valves, etc.
    The Injector Assembly consists of the Nozzle Holder and the injector Nozzle. The assembly is removed from the Cylinder Head by disconnecting the Fuel Drain Pipe and the Fuel Injection Pipe, and taking off the two nuts on the flange of the Nozzle Holder. The whole unit can then be pulled out of the Cylinder Head.
    The overhauling of the Injector Assembly should preferably be carried out by specialists who have the necessary special tools and equipment for this type of work.
    The equipment required includes a nozzle test pump and pressure gauge to enable the loading of the valve spring in the nozzle holder to be set to give an opening pressure of 125 atmospheres (1850 lb/sq. in. or 130 kg/sq. cm.).
    In emergency, the operator can fit a new nozzle to the Nozzle Holder in the following manner:-
    Remove the top cap and its copper washer.
    With the flange of the nozzle holder clamped in a vice, hold the slotted spring cap with a screwdriver and release the lock nut by the smallest possible amount to enable the spring cap to be turned. Carefully unscrew the spring cap keeping the lock nut in position until the valve spring pressure is just released. Turn nozzle holder upside down and grip by flats on the sides of body above the flange. Using a special spanner, loosen the nozzle nut and lift off the nozzle.
    Clean the mating faces of the new nozzle and the nozzle holder in fuel oil. Place the nozzle on the holder, so that the dowels are engaged in the holes, and tighten the nozzle nut. Tighten the spring cap until the lock nut touches the copper washer. Hold the spring cap, while finally tightening the lock nut. Replace top cap nut and washer and re-fit the pipes.
    After this emergency procedure, take the first opportunity of having the Injector Assembly checked on a test pump so that the opening pressure can be correctly set.


    The engine is pressure lubricated from a pump driven by a gear wheel meshing with the crankshaft pinion. The pump is bolted to the bearing cap at the gear end of the engine. It draws oil through an Oil Strainer in the bottom of the Sump and delivers it to the main and crankpin bearings and to the valve rocker gear. An external Oil Filter is mounted on a bracket which also carries the relief valve to control the pressure to 40 lbs./sq. in.
    The oil filler cap is situated near the exhaust manifold high up on the engine. The sump capacity is 8 pts. (4.5 litres) on model P2 and 16 pts. (9 litres) on model P4.
    The Dip Rod is on the Inspection Door under the Fuel Pump.  A Crankcase Pump is also fitted to this door to enable the oil to drained without requiring access to the drain plug in the bottom of the sump.
    This pump has no valves and should be operated as follows :- The cut on the handle must be towards the engine on the up stroke and towards the Discharge Pipe on the down stroke. If the pump will not start, put a little oil in at the air hole to seal the piston.
    Pump the Sump clear of oil.
    Take off the Inspection Door under the Fuel Pump and unscrew the wing nut of the Oil Strainer Screw a few turns. Slide the strainer towards the flywheel and lift out.
    Brush the strainer in fuel oil to remove sediment, and replace, ensuring that the strainer screw is securely tightened.
    Loosen the nut at the bottom of the bowl. Lower the bow few inches and bring away above the engine foot.
    Discard the old element and wash out the bowl with clean fuel oil. Fit a new element in bowl and replace whole assembly on filter head, ensuring that edge of bowl seats squarely on the joint in the head.
    If an oil pressure gauge is not fitted permanently to the engine, the 1/8" B.S.P. tapped hole on top of the Oil Filter Bracket is available for fitting a gauge for the purpose of setting the oil pressure.
    The adjustment for the oil pressure is located under the domed nut on top of the Oil Filter Bracket. Slacken the lock nut, and turn the screw down to increase the pressure. The end of the adjusting screw should always project 1/8" above the lock nut, otherwise the relief valve cannot operate and broken oil pipes may be caused.
See the instructions given under the heading of Removal of Crankshaft (P.32).
    Use a wheel puller to draw the Oil Pump Wheel from its shaft. If a puller is not available, use two 3/8" B.S.F. screws in the tapped holes in the wheel. The screws can be tightened against the Front Cover to press the wheel off.
    Remove the key, and take out the five bolts holding the pump together.
    Examine the covers of the pump and the ends of the pumping wheels for wear. The end clearance of the wheels must not exceed .010" (.25 mm.).
    When re-assembling, replace the parts in the same positions as originally fitted. Tighten the bolts lightly and tap the covers and body until the wheels revolve freely, then tighten fully.



    The Water Pump draws sea water for cooling the engine from the sea cock, The output of the pump is greater than what is required for the engine alone, so that the flow divides, after the pump, to a bypass pipe and the engine supply.
    After leaving the cylinder head, the engine supply joins up with the bypassed water, and the whole then goes into the Exhaust Silencer is discharged overboard through the exhaust pipe.
    The proportions of the bypass and engine cooling supply are set originally to give an engine cooling water outlet temperature of 140° to 160°F. at full load and speed. This allows adequate margin for a sea water temperature of 75°F. If sea water temperatures over 75°F. are experienced at places where the engine is running at full speed for a long period, the restrictor can be changed for a larger size in order to bring the engine water temperature down to 140° to 160°F. at full load. A water drain is fitted on the fuel pump side of the crankcase.
    A 3/16" Finger Pin is supplied to operate the cock, and will be found originally in the tool kit. The strainer will need little attention when the boat is running deep water, but in shallow or dirty water especially when the reverse gear is used, it may require frequent cleaning, as follows:-
    Shut the sea cock.
    Take off the two wing nuts on the top cover, remove the cover and the joint and pull out the strainer.
    Wash the strainer and replace all the parts.
    Shut the sea cock and disconnect water pipes at the pump.
    Take off Water Pump and Plate.
    Remove cover of water pump by taking out 6 screws.
    Take out the impeller by pulling it straight off the shaft. The driving pin will slide out of the slot in the shaft.
    Take out the cam by removing the screw through the body and lift out the wear plate.
    Wear of the pump parts should be confined to the cam, the cover, wear plate and perhaps the impeller. These parts can    all be easily renewed to keep the pump in first class order.
    These can be cleaned out when the parts are dismantled for overhaul. Access to the cylinder head spaces is obtained through the four cored holes on the side faces, and to the crankcase spaces when the cylinder liner is removed.
    Chemical de-scaling of the water system is of advantage in preventing blockage of the passages. Use only recognized proprietary de-scaling fluids and adhere to the makers' instructions. Do not use hydrochloric or sulphuric acid in its raw state, either concentrated or diluted.
    When the cylinder head is off, these bushes should be thoroughly cleaned out, and the water bush joints renewed if necessary.


    The exhaust gases from the engine are mixed with the cooling water in the Exhaust Silencer. The silencer and the whole exhaust pipe thus remains cool. The mixture is however corrosive and rubber exhaust pipe and stainless iron fittings must be used to withstand this effect.
    Disconnect the exhaust and water pipes. Examine the nozzle part of the Silencer Elbow for corrosion and fit a new elbow if necessary. Loosen the nuts holding the Silencer to the Cross Pipe and lift off the Silencer and the Blast Pipe. Take Cover from Silencer.
    Examine all parts for corrosion and fit new parts if the metal has become thin or shows cracks.


    Each Cylinder Head covers two cylinders, and is held to the crankcase by ten 1/2" B.S.F. high tensile steel studs. The joint between Head and Crankcase is of copper asbestos.
    The cooling water for the head is passed through the joint by Water Bushes and the cooling water is prevented from reaching the Cylinder Head joint by rubber Water Bush Joints. The Cylinder Head carries the Valve Rocker mechanism which is lubricated by oil pressure from the main oil supply.
    This cover carries the Decompression Lever. The Rocker Cover can only be lifted off and replaced when the Lever is horizontal. Before replacing the cover, ensure that the lugs on the Decompression Spindle are vertical. The cover should be seated squarely on its joint before the Rocker Cover Nuts are tightened.
    Uncouple the oil pipe. Release the set screw in each Rocker Shaft Bracket and lift off the whole assembly.
    Take off the circlips holding the outer Valve Rockers, remove the rockers and knock off the Rocker Shaft Brackets. These are a fairly tight fit on the Rocker Shaft. The inner pair of rockers can then be taken off.
The following sizes are given as a guide to the necessity for replacement of the wearing parts.
Original Dimensions
Original Clearance
Max. Allowable Clearance before Renewal
Valve Rocker Bush 
.690"/.688" dia.
(17.53/17.48 mm.)
(.03/.09 mm.)
(.13 mm.)
Rocker Shaft
.687"/.6865" dia.
(17.45/17.44 mm.)
    The plugs in the ends of the Rocker Shaft are removable for cleaning the oil passage, but normally, probing with a wire into the feed holes should be sufficient.
    When re-assembling, remember to put the Decompression Shaft in position before fitting the second Rocker Shaft Bracket. Tighten the Rocker Shaft Bracket Screws very securely.
    There should be a clearance of .010" (.25 mm.) between the face of the rocker and the end of the valve stem. While checking the clearance, it is important to maintain pressure with the screwdriver on the Rocker Adjusting Screw to disperse the oil films between the parts. A Valve Gauge is provided in the tool kit.
    Turn the engine until the push rod stops falling, i.e. the valve is fully closed. Hold Rocker Adjusting Screw with a screwdriver, then slacken the lock nut. Using the Valve Gauge between the rocker and the valve adjust the screw until the gauge is lightly gripped, then tighten the lock nut. Check the gauge and re-adjust if necessary. Repeat the procedure for all the valves.
    Completely drain the water from the engine, and remove the water pipe connected to the Cylinder Head.
    Remove Air Silencer and Elbow, Exhaust Manifold and Silencer. Take out the screws holding the Fuel Filter to its bracket.
    Disconnect the Fuel Injection Pipes at the Injector.
    Remove the Rocker Cover, Rocker Assembly and Push Rods.
    Take off the ten nuts holding the Cylinder Head, and lift it off
the Crankcase using the Lifting Brackets.
    Take off the Water Bush Joints and the Cylinder Head Joint  and examine the Cylinder Head Studs for tightness in the crankcase.
    Remove the Cylinder Head as detailed above. Remove the injectors. Scrape and brush the carbon from the face of the Cylinder Head and the tops of the Valves. Scrape the piston crowns, taking care not to allow pieces of carbon to fall into cylinder bores or down the push rod slots.
    Take the four Blind Flanges from the core holes on the side faces of the head and use the holes to clean out the water spaces in the cylinder head, finally flushing with clean water. (See also P.20, Chemical De-Scaling).
    Remove the valves (P.23) and clean out the ports, avoiding damage to the valve seats. Clean valve stems and guides.
    Weak compression in a cylinder, in spite of correct valve clearances suggests either faulty valve seating or piston rings. The head should be dismantled and the valves examined before the pistons are touched. If the valve seats are pitted and obviously not sealing properly, the valves need grinding.  (See below).
Removing and Replacing Valves and Valve Springs.
    When the Cylinder Head and Valve Rocker assembly have been removed, set the Cylinder Head on a flat surface with the valve heads downwards.
    Press downwards on the Valve Spring Seat until the Cones come clear of the top surface when a touch will dislodge them from the Valve Stem. Lift off spring seats and springs.
    Turn the head over and remove the valves. Note that the valves are all numbered to correspond with the ports, They must be replaced in their original positions.
    The outer springs should have a free length of 1 21/32" (42.07 mm.) and the inner springs 1 7/32" (30.96 mm.). Any spring appreciably shorter than this (say 3/16" or 5 mm.) should be discarded, and a new spring fitted.
    If the valve face or seat is only slightly pitted, grinding may be enough to restore them to good condition, otherwise the valve seats will require to be re-cut and the valves faced. The valve seat angle is 45°. To keep the width of the seat correct, it is relieved with a cutter giving 110°; included angle until the seat width is about 1/16" Clean all carbon from the valves and parts before replacing the valves.
    In emergency, a valve spring can be changed without removing the cylinder head. Turn the engine until the piston in the cylinder whose valve is needing attention is at the top of its stroke. This prevents the valve from falling into the cylinder and gives a stop against which the valve can be pushed to free the Cones from the Valve Spring Seat.
Valve Grinding.
    Smear a little valve grinding paste evenly on the valve face. If available, place a light coiled spring under the valve so that the face of the valve is held clear of the cylinder head.
    Press the valve down against the spring with a screwdriver, rotate it lightly to and fro, allowing it to lift occasionally under the action of the spring and move to a fresh arc of the valve seat. If no spring is available the stem will require to be lifted by hand.
    When the valve seat and face show a good bearing all round, wipe both clear of grinding paste. Wash the valve in clean paraffin or fuel oil and carefully clean the valve guide to ensure no carbon or grinding paste has entered.
    The valve spring, etc., may now be fitted.
Valve Guides.
    The guides are pressed into the cylinder head. When fitting a new guide ensure that the force is taken on the central boss and not on the flange. The clearance between the valve stem and guide is .001" to .003" (.03 to .08 mm.), i.e. a loose sliding fit. Excessive clearance will cause heavy oil consumption, dirty ports and valves and a discoloured exhaust.


    The Reverse Gear is a self-contained unit as far as lubrication is concerned and should contain 1/2 pint (.28 litre) of clean engine oil. The oil is drained from the Reverse Gear Case by a flange on the bottom. Always ensure that this is thoroughly tightened and is fitted with a good joint. An excessive quantity of oil in the Reverse Gear causes frothing and overheating, the excess oil being discharged from the breather pipe. If the quantity of oil in the gear case increases then the oil seal which prevents engine oil from entering the gearbox is faulty and requires to be renewed. "head" and "Astern" are engaged by moving the Clutch Shaft forwards and backwards by means of the screw threads on the Thrust Box and Gear Case Bush. This engages the Cone Clutch with either the Ahead or Astern Clutch. Ahead drive is direct from the Crankshaft. Astern drive comes through the Reverse Chain and Reverse Upper Wheel, to the Astern Clutch.


    While the engine is warm, drain oil from Reverse Gear. Take off Starting and Control Chains. Remove Starting Shaft Bracket on Reverse Gear Case and push the shaft forward out of the way.

    If the engine is still in the boat, loosen shaft coupling and push propeller shaft back to get 4" (100 mm.) clearance between the shaft ends.

    Remove the Gear Case Cover and find the spring link in the Reverse Chain.

    Disconnect the links and remove the Chain.

    Take off the four nuts holding the Gear Case to the Timing Wheel Cover and remove the whole case from the engine. The Ahead Clutch remains fitted to the Crankshaft.

    Unscrew Thrust Box, removing Clutch Shaft Spacer and Ball Thrust Washers. The Clutch Shaft Collar is a tight fit on the Clutch Shaft and must be removed to enable the Shaft to be drawn into the Gear Case with the Cone Clutch in place.

    Lift the Astern Clutch and Astern Thrust Bearing from the inner end of the Gear Case Bush, then remove the Gear Case Bush from the Gear Case.

    Take off the Upper Wheel Spindle Cover Plates, knock out the Bearings and Spindle and remove the Wheel.

    After removing the Ahead Clutch Nut and Lock washer, take off the Ahead Clutch complete with the Reverse Chain Wheel, using a wheel puller.

    If a puller is not available, use 3/8" B.S.F. screws in the tapped holes in the Ahead Clutch, repeatedly tightening the screws against the Thrust Bearing Plate and then tapping the end of the crankshaft lightly with a "soft" hammer. Do not use excessive force, either on the screws or the hammer, or the Thrust Bearing will be damaged.


    Wear of the clutches will show as excessive travel of the Control Wheel. Normal travel when new is less than 1 1/2 turns from Ahead to Astern.

    The Gear Case Bush is lined with white metal at its inner end. This must be in good condition, with oil way and oil holes clear. There should be no appreciable wear on the part of the bush where the astern clutch runs, only a small running clearance.

    The square threads on the Gear Case Bush and Thrust Box must be in good condition. Examine the Thrust Washers especially with regard to the condition of the cages carrying the balls.


    In general, assembly can take place in the reverse order to dismantling. Lubricate all shafts and bearings generously before assembly.

    When replacing the Gear Case Bush, see that it is fitted with the mark "TOP" on the edge of the flange, upwards.

    After replacing the Reverse Gear, the Reverse Chain can be drawn in by means of a copper wire passed round the lower wheel. When the Chain engages, help it round by turning the engine gently. Replace the spring plate of the Connecting Link so that it runs closed end first.

    Screw the Thrust Box forward into ahead position by hand. Fit propeller shaft coupling hard against the Clutch Shaft Spacer.

    Mesh the Control Chain so that the Clutch Shaft is at mid travel with the knob of the Control Wheel down. Replace the parts of the Starting Gear. Pour in 1/2 pint of clean lubricating oil.


    The timing gear train consists of the Pinion on the Crankshaft, and an Idler Wheel driving the Camshaft Wheel and the Fuel Pump Wheel. In emergency, the wheels are accessible without removing the Sump from the engine, but normally it is recommended that the engine be lifted out and the sump taken off. If the job is being done with the engine installed, great care must be taken not to damage the Sump Joint between the Timing Wheel Cover and the Sump, otherwise a leak will result.
    Take off Starting Shaft, Reverse Gear, Water Pump, Governor Control Rod, Cylinder Head and Push Rods.
    Having removed the Ahead Clutch (see P.25), take off the nuts holding the Thrust Bearing Plate and remove the plate complete with Oil Seal. Be careful not to damage the lip of the Oil Seal. Use 3/8" B.S.F. Screws in the flange of the Thrust Bearing Housing to draw the Thrust Bearing off the Crankshaft, tapping the end of the shaft with a "soft" hammer in the same manner as was used with the Ahead Clutch.
    Release the three set screws holding the Timing Wheel Cover to the Sump and the bolts holding it to the Timing Wheel Case, and remove it carefully.
    Take the central screw from the Idler Wheel Spindle, noting the positions of the Idler Bracket Washer and Lock washer. Remove the whole Idler Wheel Assembly.
    Turn the Camshaft Wheel till the nuts holding the Camshaft Bearing Housing are accessible through the cast holes and take off the nuts and lock washers.
    Remove the Inspection Door on the camshaft side, and while holding the Valve Plungers clear of the cams, pull out the Camshaft Assembly. This can be dismantled by removing the nut from the front of the Camshaft Wheel.
    The following table gives sizes which will serve as a guide to the necessity for the replacement of wearing parts
Original Dimensions
Original Clearances
Max. Allowable Clearance 
Before Renewal
Camshaft Journal
(Small ) Dia.
(25.30/25.35 mm.)
(.03/.13 mm.)
(.25 mm.)
Camshaft Bush
(Small) Dia.
(25.43/25.38 mm)
Camshaft Journal
(Large) Dia.
(44.35/44.40 mm.)
(.03/.13 mm.)
(.25 mm.)
Camshaft Bush
(Large) Dia.
(44.48/44.43 mm.)
    Replace the parts in the reverse order to that used in dismantling.
    Before meshing the gear wheels, set the Crankshaft with the piston nearest to the Reverse Gear at the top of its stroke, i.e. with the key way of the Crankshaft Pinion vertical.
    Mesh the marked space between two teeth on the idler Wheel with the marked tooth on the Pinion and similarly, mesh the marked points on the other wheels, marked spaces going opposite the marked teeth.
    Take care in the fitting of the Thrust Bearing Plate and its Oil Seal. Any trace of damage to the sealing lip will cause an oil leak. If a new seal is being fitted, turn the Crankshaft Spacer so that the sealing lip does not run in the groove made by the old seal.



    The Flywheel is securely keyed to the Crankshaft by two sets of Twin Keys. The Starting Pawls are held on Pins pressed into the Flywheel and engage with the Lower Starting Wheel which runs on the End Cover.
    These parts should not be removed unless it is essential for access to other parts of the engine.
    Take off the Flywheel Retaining Plate.
    With the Key Punch provided, drive in the lower keys slightly against the Lead Stop. This slackens the keys and makes it possible. to pull off the Flywheel.
    The Lower Starting Wheel is retained by the steel ring with four countersunk screws.
    The Starting Pawl Pins can be driven out of the Flywheel.
    When replacing the Flywheel, it is necessary to ensure that the Key Plate is on the shaft and it is vital to have the lead Key Stops correctly in place at the back of the lower keys. (Spare stops will be found in the tool kit). If this is not done, removal of the flywheel on a future occasion will be extremely difficult and damage will be caused to the crankshaft.
    Great care must be taken in removing this cover, If this is being done with the Sump in position, owing to the danger of damaging the Sump Joint, and also the Oil Seal. Any damage to the lip of the seal will cause a leak when the engine is running. When possible, it is recommended that the end cover is not disturbed until the engine is being removed and the sump taken off.


    With the engine installed, the Pistons and Connecting Rods can be withdrawn upwards after removing the Cylinder Head. If the engine is out for overhaul, it is probably easier to remove and insert the pistons from the bottom of the liner while the crankshaft is not fitted. Before removing a piston and connecting rod, note that the cylinder number is stamped at four places on the injector side of the engine :- (1) on the Piston Crown ; (2) on the top face of the Cylinder Liner ; (3) on the main part of the Connecting Rod adjacent to the split ; and (4) on the Connecting Rod Cap. These four marks must always be on the fuel pump or injector side of the engine.

    If a new piston is being fitted, It will be found to be marked "INJECTOR SIDE " on the crown. The Cylinder number should then be marked adjacent to this, either by a numeral or by centre dots.


    Access to the Connecting Rod Set screws is best obtained through the Inspection Door under the Fuel Pump, with the Piston at a suitable position in its stroke.

    Bend back the Lock washers under the heads of the Set screws before slackening them.

  Keep the two halves of the Crankpin Bush in a safe clean place so that they can be replaced in exactly the same position as they were originally.

    If the Piston is to be drawn through the top of the Cylinder Liner, the upper 1/2" of the Liner will require to be scraped clear of carbon to enable the rings to pass easily. Push the Connecting Rod up from the bottom, being careful not to disturb the Cylinder Liner.

    Remove the Circlip from one end of the Piston Pin.

    Heat the Piston until it is as hot as can be handled then knock out the Piston Pin.


    The rings must all be free in the grooves, and the slots in the oil control rings free from carbon. The drain holes behind, and also below the oil control rings must be clear, and there should be no appreciable thickness of carbon on the piston skirt.

    The following table gives sizes which will serve as a guide to the necessity for the replacement of wearing parts.

Original Dimensions
Original Clearances 
Max. Allowable clearance
Before Renewal
 Piston dia. at bottom of skirt at right angles to piston pin
(82.44/82.41 mm.)
(.09/.14 mm)
.015" (.38 mm.) or when Piston wear exceeds .005" (.13 mm) or liner
wear exceeds 
.010" (.25 mm)
 Cylinder Liner dia.
(82.55/82.53 mm.)
(a) Plain Piston Rings
Groove Width
(2.41/2.43 mm.)
(.03/.08 mm.)
(.25 mm.)
 Ring Width
(2.35/2.38 mm.)
(b) Oil Control Rings
Groove Width
(4.83/4.85 mm.)
(.07/.12 mm.)
(.25 mm.)
Ring Width
(4.73/4.76 mm.)
 Piston Ring Gap
(.25/.38 mm.)
(1.5 mm.)
 Piston Pin Bush dia.
(30.20/30.25 mm.)
(.04/.09 mm)
(.18 mm.)
 Piston Pin Dia.
1.1875"/1.1873" (30.162/30.158 mm.)
    Fit the Piston to the Connecting Rod so that the marked cylinder numbers lie on the same side. Heat the piston so that the Piston Pin can be easily moved. Ensure that both circlips are fitted properly in their grooves.
    Set the piston rings so that the gaps are not in line, oil the piston, and liner, and insert into the cylinder bore. When inserting from the bottom, the chamfer on the cylinder liner will assist the piston rings to enter. When inserting from the top, the rings must be compressed fully to enter the cylinder bore.
    Clean the halves of the Crankpin Bushes and their seats thoroughly. Position the top half bush into the Connecting Rod with the locating lug in its slot and pull the rod on to the crankpin. Similarly, insert the bottom half bush in the cap, place the cap in position, fit new lock washers to the set screws and tighten up firmly. Turn the lock washers on to the flats of the hexagon.
    Note.--Before assembling, always oil the piston surface, the cylinder bore, the half bushes and the crankpin. Never file the mating surfaces of connecting rod and cap. The bearing bushes need no "bedding-in" even when new, and should not be scraped or altered in any way.
    After refitting a crankpin bearing, turn the crankshaft by the flywheel to ensure that the bush is not binding on the crankpin. If the shaft is tight to turn, undo the crankpin bearing and examine each half bush and its seat for dirt. This is the usual cause of a badly fitting bearing. The cleanliness of the parts cannot be over emphasized.
    Pistons are available .020", .030" and .040" oversize. Such pistons are clearly marked on top with their amount oversize. It is essential, if new rings are required for oversize pistons, that this fact be stated when ordering the spares.
    The diameters for reboring of Cylinder Liners to suit these oversize pistons are given on P.31.


    The liners are of the wet type, sealed at the top by the metal to metal joint at the flange, and at the bottom by two rings of synthetic rubber. When a liner has been withdrawn, new rubber rings must be fitted.
Removal and Assembly of Liner.
    With the cylinder head off, and piston and connecting rod out, use  a block of wood in the crankcase to lever or knock the liner clear of the top seating.
    If the liner is very rusty, there may be some difficulty in getting the bottom seating through the upper bore of the cylinder block, but it can be roughly cleaned off with emery paper and by rotating the liner as it is pulled, it will come clear.
    When a liner has been withdrawn, take the opportunity to clean rust and scale from the inside of the crankcase water space, and examine thoroughly for thin places.
    The original size of the liner bore is 3.249"/3.250" (82.52/82.55 mm.). When wear, measured on the diameter, exceeds .010" (.25 mm.), the liner should be replaced by a new one, or rebored to take an oversize piston.
The requisite cylinder bores for oversizes are:-
3.269"/3.270" dia. (83.03/83.06 mm.)
3.279"/3.280" dia. (83.29/83.31 mm.)
3.289"/3.290" dia. (83.54/83.57 mm.)
    The top edge of the cylinder liner should project .005" to .009" (.13 to .23 mm.) above the crankcase top face. Check this with a straight edge and feelers after fitting the liner without the rubber rings.
    A trace of jointing compound on the seating for the liner flange will assist in preventing corrosion of the face.
    The liner will be found to slide easily through the rubber rings If they are first smeared with soft soap or very soapy water.
    After fitting the liner, replace other parts and clamp down with the cylinder head as soon as possible.
    The crankshaft is made from alloy steel with cast iron Balance Weights each held to the webs with two high tensile screws. The crankpins are hardened to provide the best possible journal for the copper lead lined Crankpin Bushes. The Main Bearing Bushes are white metal lined and run on unhardened journals.
    Oil for the crankpin bearings is carried from the adjacent main bearing via a sludge trap in each crankpin. The sludge trap is a large drilled hole closed by a screwed plug.
    An Oil Thrower is shrunk on to the crankshaft at the flywheel end to assist the Oil Seal in the End Cover in preventing oil leaks.
Removal of Crankshaft.
    Take off the Reverse Gear, Timing Wheel Cover, Cylinder Head, Flywheel and End Cover. Remove the Oil Strainer from the Sump and take out the screws holding the Oil Strainer Bracket to Sump.
    Turn the engine upside down and remove the Sump.
    Take off the Oil Pipes and the Oil Pump.
    The nuts retaining the Main Bearing Caps are of the self locking type ; take off the nuts and lift the caps. Each cap is numbered so that it can be replaced in the same position as originally fitted. Lift out the Main Bearing Half Bush from the cap or the shaft. The half bushes must also be replaced in the same position as originally fitted.
    Lift out the Crankshaft and remove the remaining half bushes.
    Do not remove the Balance Weights unless it is essential.
    The plugs for the sludge traps should be removed and the Oil holes all thoroughly cleaned. Ensure that no loose dirt is left in any oil holes, or the bearing may be damaged when the engine is started. The plugs should be tightened firmly into the sludge traps and locked by means of a centre punch mark on the threads.
    If the Balance Weights have to be removed, unscrew the socket head Balance Weight Screws. The locking action of the copper plugs can be easily overcome. Clean the serrations on the head of the screw.
Inspection of Crankshaft.
    All journal surfaces should be smooth and free from scores and ridges.
    The following table gives sizes which will serve as a guide to the necessity for the replacement of wearing parts:-
Original Dimensions
Original Clearance
Max. Allowable
 clearance Before Renewal
Main Bearing Bush Dia.
(63.55/63.56 mm.)
(.05/.09 mm.)
(.18 mm.)
Crankshaft Journal Dia.
(63.46/63.47 mm.)
Crankpin Bearing Bush Dia.
(57.19/57.16 mm)
(.05/.09 mm.)
(.18 mm.)
Crankpin Dia.
(57.10/57.11 mm.)
Note.--The diameter of the bushes is measured with the two halves clamped up in their housing.
The following undersize bearings are available:-
- .010"
(56.85/56.86 mm.)
(63.21/63.22 mm.)
- .020"
(56.59/56.60 mm.)
(62.95/62.97 mm.)
- .030"
(56.34/56.35 mm.)
62.70/62.71 mm.)
    Undersize bearings are marked on the back with the figures -10, -20, -30, to indicate the amount undersize in thousandths of an inch.
    When the crankshaft has been reground ensure that the edges of the oil holes are well rounded and that no trace of grinding sludge is lying in any oil hole.
Refitting the Crankshaft
    Fit Main Bearing Half Bushes into the crankcase seats with the projecting lug correctly located in the recess.
    Handle all Half Bushes with care and ensure that dirt is removed both from the seat and from the bearing surfaces. Oil the bearing surfaces generously before fitting the crankshaft.
    Fit the Main Bearing Caps, ensuring that they are the right way round. They are marked with corresponding numbers at the mating faces.
    Pull down the nuts for the caps very tightly. Check that the crankshaft can still be turned easily after each cap is tightened. If the shaft is tight, remove the cap and examine the bearing surfaces and the seats for the bushes. Any trace of dirt or foreign matter can cause tightness.
    Replace the Oil Pump on the Gear End Main Bearing Cap. While tightening the nuts holding it to the cap, ensure that the driving gear wheel is kept in true alignment with the Crankshaft Pinion.



If the engine turns freely by the starting handle, two general sources of this trouble are (i) the fuel system, and (ii) the parts ensuring good compression.

(i) Fuel System. The "creak" of the injectors should be clearly heard. If not:

    Check for sufficient fuel in the tank.

    Check that Fuel Cock is open.

    Check that the gauze filter in Feed Pump, and the Fuel Filter are not choked.

    Check the whole system for air locks, by venting at the plugs on Filter and Fuel Pump (P.9).

    Check that Fuel Pump is operating by taking off the cover and watching the elements rising and falling. Take off the Fuel Injection Pipes and watch for the spurts of fuel. Remove delivery valve holder and check that valve and spring are free, and undamaged.

    Check that Nozzles are spraying correctly. This can be done on the engine by turning the Nozzle Holder so that the Nozzle sprays into the open air. Turn the engine by hand for this test.

(ii) Compression Parts.

    Check that nuts on Cylinder Head are very tight and that Cylinder Head Joint is in good condition.

    Check that the Valve Springs are undamaged.

    Check that the valves are free in their guides. have the correct clearance, and are seating well. If not, clean the stems and guides, and grind the valves (P.24).

    Check that the Piston Rings are free in their grooves and that loose carbon is not interfering with their operation (P.28).

    Check that the Cylinder Liner and Piston are not excessively worn (P.30).


(i) Fuel System.

    Check all pipe joints, especially the Fuel injection Pipe joints for leaks.

    Check for air in system. Vent if necessary (P.9).

    Check Fuel Filter Bowl to see whether the fuel contains water.

    Check that the level of the fuel in the tank in gravity fed systems is sufficiently above the level of the Fuel Pump to give a good flow (P.7).

    Check delivery valve spring on Fuel Pump (P.15).

    Check that Fuel Pump is operating correctly and that plunger springs are undamaged (P.15).

    Check that nozzles are spraying correctly. (P.17).

    Check injection timing (P.15).

    Check that correct type of fuel is being used (P.5).

(ii) Compression Parts.

    Check for broken valve springs and sticking valves, or incorrect valve clearances (P.22 and P.23).

    Check for excessive carbon on piston and in air and exhaust ports.

(iii) Miscellaneous.

    Check that Air and Exhaust Silencers and the exhaust pipes are not choked or restricted.

    Check that engine is not overloaded, by running with clutch in neutral.


(a) Black smoke, indicating faulty combustion.

(i) Fuel System.

    Check that all the nozzles are spraying correctly (P.17).

    Check that all the plungers in the fuel pump are working and that the plunger springs are intact. (P.15).

    Check injection timing to see if it is too far retarded (P.15).

(ii) Compression Parts.

    Check for low compression on one or more cylinders ; if faulty, investigate as in Para. 1 (ii) above.

(b) Blue smoke, indicating the burning of Lubricating Oil.

    Check that correct grade of lubricating oil is being used (P.5).

    Check that oil control rings on piston are clean.

    Check that there is not excessive wear an the liner or piston (P.29).

    Check that there is not excessive clearance between the valve stem and the guide (P.23).

    Check that the valve rocker bushes are not badly worn, causing excessive oil to lie on top of the cylinder head and run down the valve guides (P.21).


(i) Bearings.

    If an oil pressure gauge is fitted, check the pressure. In any case, stop the engine as soon as possible.
Check bearings for overheating and clearance (P.32).

(ii) Piston.

    Check for excessive carbon on crowns.

    Check for broken piston ring.

    Check for excessive clearance between liner and piston (P.29).

(iii) Fuel System.

    Check that all nozzle holes are clear, and that nozzle stems are perfectly free (P.17).

    Check injection timing to see if it is too far advanced (P.15).

(iv) Idler Wheel and Camshaft Wheel.

    Check Idler Wheel and Camshaft Wheel for excessive play in the bearings (P.27).


    Check for Leaks.

    Check for blue smoke in exhaust. If present, see Para. 3(b) above.


    At full speed the water jacket of the cylinder should be about as hot as the hand can bear. The cylinder head should be too hot to hold, i.e. the temperature of the water at the outlet from the cylinder head can be 140° to 160°F.

If the engine is overheating:-

    Check that the Sea cock Strainer and the Suction pipe for the Water Pump are clear (P.20).

    Check that the restriction fitted to the flange at the inlet the cylinders is clear.

    Chemical de-scaling of the water system is of advantage in preventing blockage of the passages by scale. A typical de-scaling compound is Houseman & Thompson's "HTL Solvent."  DO NOT use hydrochloric or sulphuric acid.


    If the loss is gradual. it may be due to fouling of the vessel below the water line. A growth not visible to the eye is sufficient to affect the speed.

    If the boat is slippery to the hand, it requires cleaning. It pays to use anti fouling paint, as the best qualities will resist growth in a temperate climate for four months whereas growth begins on ordinary paint in four weeks.


(i) Running Hot.

    Check that the correct quantity of oil is in the case. Excess oil causes frothing and overheating (P.24).

    Check that an obstruction in the propeller or a bent blade is not causing the clutch to slip.

    Check the Gear Case Bush for overheating.

(ii) Overheating of Gear Case Bush.

    Check that the correct quantity of oil is in the case. Low oil causes the bush to be starved of lubricant.

    Check that the shafts are in line. Remove the coupling, and check the alignment of the shafts with a steel rule.

(iii) Leakage of Oil.

    Check that the bottom flange is tight and joint undamaged.

    Check that breather pipe is not obstructed.

    Check that oil level is not increasing, due to a faulty oil seal in the Thrust Bearing Plate.

(iv) Clutch Slipping.

    Check that a propeller blade is not bent.

    Check that shafts are in line.

    Check whether correct propeller is fitted.

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