Boat Fault Finding - Marine Engine Problems

That seal is usually used, together with an aluminium tube, to seal the maximum speed stop screw on the throttle lever (The one that is contacted by the lever at full throttle).

I have rarely needed to bleed that particular screw, with the one on the body being sufficient to start the engine.

The screw you mention is fitted into something that an best be described as the head of a bolt with a lock not. As long as you did not loosen the locknut, or move the bolt, you can not have altered any adjustment. In any case the adjustment is used to fine tune the action of the governor valve to prevent the engine surging up and down. Mall adjustment can lead to a higher idle speed, but I can not see it causing smoke. The maximum speed stop might if it was undone too far.

From your post, I wonder if your pump actually had a bleed screw in the position stated. I fear that you may well have undone the governor adjusting screw. All I can suggest, if this is the case, is that you loosen the "bolt" with the engine on idle, until it starts to rev up and down. (I just hope that it does), then slowly tighten it until the speed is steady.

If this fails I am afraid that you must get the pump to a diesel specialist for re-setting.

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1 - Oil Level
I fear this action (and the failure to fit the sump pump - how are you going to change the oil without loads of mess?) poses questions about the rest of the job. Overfilling any sump is likely to result in blue smoke, but more important on a diesel, in severe cases may lead to engine run away when you just can not stop the engine revving.

2 - Air Filter
Many engines do not run with air filters and I have seen a few marine diesels where there was not even an inlet manifold, however it is not good practice. It leads to noise and the possibility that the engine ingests something like a chunk of rust that damages the valves or pistons etc. If the engine cover is close to the air intake and is covered with foam or something, could this be being sucked over the intake? If so, that may be why the engine just stops.

3 - The engine just stops
In view of what you have said, once you check that nothing is blocking the air intake, I would be very suspicious of the quality of the job and would want to take a very close look at the fuel lines and filters.

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I am afraid I am not going to be much help. You appear to have checked everything you should, and from what you say, all sounds fine.

I am concerned over the size of prop because it sounds far too large - ring a prop specialist and ask them for the recommended size for the engine and boat combination.. However an oversize prop usually causes overloading which shows itself with black smoke - not white.

Your original boiler should always have had more than sufficient oxygen to burn all the fuel, however in a diesel, there will be parts of the combustion chamber that get starved of oxygen, so will not fully combust the fuel. This is likely to give rise to the nasty smell. The particulates that diesels produce (very small pieces of carbon) will also not do you any good at all.

It is possible that the white smoke is actually steam + particulates, caused by the exhaust pipe and silencer running cold, but I regret that apart from lagging, I can not see how to rectify this. I would not expect lagging to be very successful. If you can get to a river and give it a good, higher speed, run, if the "smoke" eventually disappears you can conclude its steam.

In view of what you have already done, the only thing left is to fit a taller exhaust stack - and spoil the look of the boat.

White smoke can be caused by the injection timing being incorrect - I forget if its advanced or retarded, but it matters little because whichever way it is, the timing has to be checked.

I do not know your engine, but suspect that the timing is adjusted by annular shims placed under each injector pump.

If you look at the rod coming out from either side of your pumps and forming part of the pump linkage, you should see a line scribed to one side of each pump. With the links pushed one way (often with a gauge between the end of the links and the governor) both lines should be flush with the side of their respective pump. If not the linkages needs adjusting. As you can see there is a distinct possibility that you need a gauge and full instructions (which I do not have).

Once the linkage has been set the individual pump timing can be checked. This usually involves a high level fuel tank, the removal of the delivery valve, the fitting of a swan neck, and setting the engine to a specific position. Once this is done shims are added or removed from the pump to get the correct number of drips from the swan neck.

The above probably looks like gibberish if you have never timed a diesel, so I fear its a case of getting in a specialist for that range of
engines, but first I would get the pumps checked for wear in the roller cam follower that they usually employ.

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This certainly sounds like burning oil, but you appear to have had every thing done that you should.

My Bukh does this, and strangely new engine mounts which stopped it jumping about so much, made a big difference - I surmise oil was being drawn into the crankcase breather system.

If it is after a period of slow speed/idle there is an outside chance that its valve stem oil seals, but this should not really be the case
on a diesel.

Make sure you do not overfill the oil & check any valves in the breather system.

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White AND black smoke?. If the white is soon after a cold start, and the black once under way, I would suggest that you check your heater plugs to ensure the engine is starting as quickly as possible, otherwise it fills the engine and exhaust with unburnt diesel which will "burn" off as white smoke.

Then check you aircleaner is clean (if fitted) and ensure a free supply of air to the engine room. Check any air trunking for kinks, dead mice, water etc. If all this is ok, check your prop is clear.

Only after checking the above consider getting the injectors serviced. I would advise that you take them to a diesel specialist for overhaul or exchange and settle with the company - even if you do have to pay someone to remove & replace them. The injector pump is far less likely to cause problems, so try injectors first.

If this is a wet exhaust boat, are you sure your white smoke is not steam, caused by a faulty raw water pump or impeller. I have also known de-laminating exhaust hose to cause such back pressure that the pump can not push water into the injection elbow, so the exhaust steams.

Not knowing what type of boat we are talking about, is it possible that your hull needs a scrub off and is causing the engine to overload by resistance to moving through the water - especially if the prop was never 100% correct for the boat - this will not normally apply to a narrow boat.

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Did anyone loosen the injector pump mounting nuts? - if so I suspect your pump timing is now wrong. If you look on the flange that the pump is bolted to, you should see a pointer at one corner. This should be pointing to a line on the pump flange.

Otherwise I can only see two possible causes.

1. One or more of the injectors are faulty - even if they have been overhauled. Who did them? Did you take them out and personally take them to the specialist for overhaul? Were new copper washers and nozzle heat shields fitted (and the old ones removed)? - You can often get away with not renewing them, but if any came out on the injector and were not renewed, they are now missing.

Many "diesel mechanics" think they can "overhaul" injectors with a simple cleaning kit. In my view they can not, especially the type used on a 1.5 (pintaux). The only people to do it are the specialist injection equipment people. If you paid a mechanic to do it, I would demand to see the bill/invoice from the specialist. If the injector(s) is dribbling, has a bad spray pattern, or has the auxiliary spray hole blocked, you will get smoke.

2. One or more of the "top hats" that are a very light push fit into the head, at the base of the injector "hole" came out on the injector and was discarded by the overhauler. This would give low compression and white smoke, but also more reluctant starting.

Sorry that I can not be much more help at long range, I would also like to know why you had the overhauled. If you were trying to solve a problem, that problem may not be injectors (or pump) and may have simply got worse.

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Find your injector pump - follow the pipes from the injectors, back down to the pump. If the pump is stuck out the side of the engine (in a similar position to an old petrol engine's distributor) it is a BMC 1.5. If it is lying parallel to the engine block its a BMC 1.8. The numbers are often cast into the block, below the manifolds.

The best way to start from cold is to set the engine to about half throttle (strictly a diesel should start on tickover), hold the heaters on for a slow count to 30, and then operate the starter. As soon as it starts, reset the throttle to a no faster than a fast tickover for a few minutes. This ensures oil circulation with minimal load.

If the engine does not start after a couple of tries, you need to get the heater plugs checked.

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My engine doesn't want to start, now I don't know too much about diesel engines so you'll have to forgive my ignorance. It will start with persuasion (I'm a chemist, I think this probably explains a lot) and will start again once up to temperature. I have checked the heaters and they are taking volts, does this mean that they are working?

No. The fact that the "ignition switch"/heater button connects the cable to the battery does not mean that any current is being drawn.

Take each heater plug out (if the engine has been overhauled they should come out easily - if they are very stiff & snap off, I am afraid you got a **** overhaul) connect them to the battery, terminal to pos. & body to neg. Use thick wire (each may draw 20 amp at first). the tip of each plug should glow. If it does not, you have found the problem, so replace the faulty ones. Refit with copperslip (copper grease).

Keep your flesh clear of the tips when testing!

If all the plugs are working, there is something else preventing a sufficient high temperature being reached in the cylinder. The diesel relies on the compression of air to create a sufficient temperature to ignite the fuel - your engine also needs the assistance of heater plugs for cold starting.

Things to check are:
are you sure there is no air still getting into the system - loose joints etc.
do you have clearance on all the valve rockers (tappets) or are some tight, allowing compression to leak past the closed valves? If you can check the clearances on an old car, you can do it on this engine.

If all the valves have a clearance on them, I suggest that you get another engineer to do a compression check. Unfortunately you need a special bolt in diesel gauge for this. Make sure you get a written report, because this may be the start of litigation or dealing with Trading Standards.

I think that this may also relate to my other problem namely, white smoke. Once said engine is running I get a lot of white smoke out of it, this also smells of unburned diesel.

This is not unusual, and the longer you have to "persuade" it into starting the worse it will be. Basically its unburnt fuel vaporising from the exhaust and cylinder walls. It should clear within 10 minutes or so. If it does not, suspect faulty injector spray pattern or incorrect spray pressure. Your injectors should have been sent away for overhaul & re-setting as part of the engine overhaul.

Other boaters have advised me that I need to 'lean out' the engine. I have looked and can only find one adjustment, which controls the idle speed but does nothing for my white smoke.

They are talking **** - you are correct. Tell them to go back to the petrol engines they obviously do not know! there is no adjustment you can do.

Do you know how I might be able to get less fuel going through the pump? I don't even know if there is a standard fuel pump for this type of engine.

Yes - its a hydraulically governed DPA injector pump and it is set to suit a particular engine on a test rig. This is something else that should be done as part of the overhaul. Only by putting it on the rig can the max. fuel and automatic advance/retard be set. This needs to be done by a specialist.

I do wonder if the injector pump timing has been correctly set. Look at the side if the engine with all the thin pipes on it. You will see the injector pump is a round body with a "turret" on it, mounted to the engine by a triangular flange with three nuts securing it in place, through elongated holes.

Look at one of the upper corners of the triangular flange, on the engine block side (the front one, I think) and you should see a pointer secured to the block flange by two screws. A line scribed (cut) on the pump flange should be in perfect alignment with this pointer. If not, slacken the three nuts and force the pump to twist to align the pointer and mark.

Unfortunately the pointer should have been set during overhaul, using a special tool to remove the play in the pump drive - we have no idea it this was done.

One symptom of incorrect injector pump timing is white smoke (incomplete combustion), so you could try running the engine, under load for about an hour (to remove any unburnt fuel) and then try slightly turning the pump. The engine speed will alter, but with a bit of luck and care, you will find a point where the white smoke is at the minimum. If you do, then you can assume the timing was wrong, so get the pointer set and the timing redone by a BMC specialist (e.g. Calcutt).

I am concerned because the injector pump drive gear needs an oil jet on it. This and its associated stariner is provided by a vertical and horizontal bolt head on the other side of the engine - towards the back. These do block with old oil or stuff left over from cylinder boring and should be checked and cleaned. If they block the gear wears and completely messes up the timing.

Steps:
1 make sure heaters are working
2. Make sure there is no air in the fuel.
3 Make sure all valves have clearance
4 Visual check of pump timing (adjust if out)
5. Get professional to check pump timing, pointer setting, & compression.

There is a Dutch site (can't remember the name) that I understand has a copy of the manual for download, otherwise talk to Calcutt Boats of Southam.

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What I think you are asking for is the Lucas part number and our 1.5 does not have a legible part number on it - in any case the starter body (with the part number) may not be the original.

I do not have this to hand, but am sure that Calcutt Marine of Southam could supply you with an exchange unit, or any decent autoelectrical outfit could overhaul an existing unit.

You should take care when taking starters from vehicles because although the pinion (gear) might have the correct number of teeth, and the fixing bracket might have compatible mounting holes, the solenoid could well be in an inappropriate place for marine use.

Either ask someone with a 1.5 in their boat if you can look at their starter to find the number, or repost the question on the news group uk.rec.waterways.

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You have fresh water cooling already, I suspect you mean direct cooling. Diagrams on www.reading-college.ac.uk/marine .

Make sure there is a way for any gas/air that is trapped in the top of the skin tank to be removed, and also make sure you do not have an excessive build up of blacking on the outside of the swim on the skin tank. If that does not solve the problem I think the easiest way to solve the problem is to fit a number of pipes outside the swim on the opposite side to your skin tank. These would typically be four of half inch ENGINEERS - not plumbers, copper or bronze/brass pipes, about 4 to 5 feet long running betwen headers (they are commercially available, but may take some finding). The headers are fitted through the hull and piped in series with your existing skin tank. The engine thermostat will ensure you do not overcool.

You could also bend up a single length of (say) 1.4 inch bore pipe in a serpentine fashion and mount this outside the other swim side.

If you can "dump" the hot air, you could put a car heater box and blower in the calorifier circuit (or where a calorifier would be fitted), and turn the blower on when on the river.

As long as you have no head gasket faults or cracks in the head or cylinder (and as you say you are a motor engineer I assume you do not) I think the problem is simply a too small or badly designed skin tank.

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It runs OK at canal speeds, up to about half max revs, but then starts to overheat. I have installed a car radiator and fan in the calorifier circuit (mainly to keep feet warm in winter); the radiator is about 3 ft above the engine, and running this keeps the engine temp OK at higher speeds (which we need to get up the Severn from our mooring) but this is not much fun on hot days.

The thermostat is OK and I have tried running pressurised and not: this doesn't seem to make any difference. I am fairly sure the pump is OK (or the calorifier circuit would not work) and I have put a pipe from the top of the tank to the overflow bottle, so there is no air at the top of the tank. Temp gauge and alarm have different senders, so I don't think it is instrument problem. Doesn't use water, so I assume its not head gasket gone.

Boat has been drydocked 4 times, so has 800microns++ of bitumen covering the outside of the tank. I have not yet tried cleaning any rust/sludge off the inside of the tank (tricky) or scraping the bitumen off.

The obvious answer is make the skin tank bigger by welding a second tank on the outside of the hull, but this is expensive (at least at the local yard RWDavis). Do you have any thoughts on alternative solutions?

I am fairly sure its is a "size of skin tank" problem. I saw a lot of this when I was running the engineering of a Thames yard with narrow boats overheating then flogging upstream though they never had a problem on the canals.

You appear to have done all you reasonably can - your radiator more or less proves the problem.

I can think of one solution, but it might end up being more trouble than its worth - but if you are handy (which you appear to be) you could always "disconnect" my suggested mod if it all goes wrong.

I hesitate to suggest putting anything that may be thought of as vulnerable outside a NB's hull, but it occurs to me that you could fit a set of keel cooling pipes outside the other (non skin tank) swim. You would simply pipe these in series with your existing skin tank.

You need a couple of "faired" headers and a set of keel cooling pipes. Try contacting Norris of Isleworth or the engine manufacturers to try to get a lead on ready made up systems. If you can not get a ready made up system you need to organise four pipes running between the headers, outside the hull, each about 1/2 to 3/4 in. diameter and about 6 feet long if you can accommodate this length on your swim. Ideally they would be of bronze or brass, bout I suspect thick walled ENGINEERS copper tube (not 15mm plumbers) would also do the job. They are normally fixed but compressed rubber bushes to allow hull movement, but seeing this is for a steel narrow boat I think brazing, soldering etch would do fine.

All you now need is a dry dock/slip, and hole cutter and drill. Carefully mark the swim and drill two holes to accept the headers , seal and fit. I think I would use nylon washers and sealant to ensure a watertight fit. Then pipe in series with the skin tank, add more antifreeze (50% to minimise corrosion) and I think your problem will be solved - what happens if you bounce the pipes off something goodness only knows. If a pipe leaks you will start to loose coolant.

Your thermostat will ensure your calorifier (and radiator) will continue to work, and that the engine stays at optimum operating temperature.

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Strictly speaking you do not need a solenoid, although good practice means one is fitted to minimise voltdrop.

These are normally car starter solenoids of cars built up the 80s with an inertia starter.

Go to any car electrical specialist and as for an inertia starter solenoid. Ideally try to get one from an automatic that uses an inhibitor switch - if you can ignore the next paragraph - if you can not take note of it.

This will almost certainly be an "earth return" unit, bolt it to the engine or a piece of wood, so the negative is not connected to the hull (could, and only could lead to corrosion).

If you have an inhibitor switch one, you will see two bolt type terminals - these take a battery supply to the heaters. You will also see two small - probably blade type - terminals. one is connected to the heater position on the ignition switch, and one to the battery negative or the engine block.

If its an ordinary solonoid you will only have one small terminal. This is connected to the heater position on the ignition switch. An "earth" is wire the run from a mounting screw to the block or battery negative IF ITS NOT MOUNTED ON THE ENGINE.

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I know of no-one who publishes diagrams.

Normally a Wortham-Blake marinised engine would have a marine exhaust manifold. Usually this is made out of cast alloy and surrounds the manifold with a water jacket which is plumbed between the engine coolant outlet and the exhaust mixing elbow (the thing that has dissolved on your boat).

As you say you have a "normal" car exhaust manifold, all you need is the mixing elbow. The idea is to introduce the water below the manifold level, to minimise any danger of the engine drawing water back into the exhaust ports.

You need a mild steel plate to match the end of the manifold (probably oval with one very large hole in it, and two smaller ones), a black iron plumbers bend of suitable size and threaded pipe to connect the exhaust hose to (nipple). Drill the bend fairly low down, and insert a scrap of copper pipe. Get this brazed or silver soldered in, making sure the pipe is bent so it injects water downwards. Get the plate welded onto the bend in a suitable position, and bolt the whole lot up, connecting the water supply by hose & clip to the injection pipe.

Do not forget to lag the manifold and the hot end of the bend very well.

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This is difficult without seeing the engine, but it sounds like a heat problem. When the engine is hot, remove the plugs and clamp the to the engine where you can see them. Crank engine. If you still have a fat blue spark you can be 75% certain the ignition system is OK. IF not suspect (according to type of ignition) Contact points, capacitor, stator (all under flywheel), coil, plug leads (measure resistance on 20 Kohm scale, expect a maximum of about 25 Kohm per metre - so about 4 or 5 Kohm), Electronic ignition module.

If you do have a good spark when hot, its may be too rich a mixture - blocked air ways into engine, or bad adjustment.

After that its looking for loose joints (like carb to block) that allows the engine to suck in air, or simply worn parts.

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EXHAUST SYSTEM MATERIALS
I purchased a used boat that has an exhaust run about 7 feet long. The  previous owner installed a steel pipe about 4 feet long and the remainder rubber exhaust tubing. All the standards for exhaust systems that I have read, recommend rubber exhaust tubing, however, filament-wound tubing is also sold for this purpose. Of these three alternatives steel pipe is the least expensive. Why is steel pipe not used instead of the other two?

Steel pipes rust and may well set up resonance both inside themselves and outside.

In the UK the "rubber" exhaust hose is a composite of rubber and fabric sandwich reinforced with a spiral wound steel wire between the laminations.

This allows the rubber to damp the sound energy within itself and not get crushed/flattened when it goes through bulkheads and round corners. It also allows the inner lining to char to a certain extent (when to cooling water fails) without leading to hose failure and consequent leaks of cooling water into the boat.

As long as it was adequately supported so any resonance tended to be damped, I would have no problem is using black iron plumbers pipes, but I would expect them to rust through after a number of years (by which time the rubber hose would have probably failed due to periodic loss of cooling). Just make sure some flexible hose is used to allow the engines to vibrate!

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First you may simply have picked up some fuel with a low octane rating, this will give rise to diesel knock which can sound like a rattle. It may go away when the engine gets hot.

If you suspect that it started after filling with fuel, add a few gallons of road diesel (I know it will cost you) and see it it improves. If so you can be fairly sure its the fuel.

You might have broken a piston ring or something, but its unlikely.

Make sure all the engine feet are tight onto the beds. If the sound appears to be coming from just in front of the gearbox I fear the gearbox drive plate is starting to fail. I would suggest the box is taken off and the plate inspected/replaced.

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The original engine had an element type oil filter inside a can with a centre bolt, but many have been converted to a screw on throw away canister type.

If yours is the later, I would suggest that you remove it and take it to whoever supplies your motor trade with parts (we call them Motor Factors). They should be able to pattern it up and supply a suitable replacement. They may also be able to supply a replacement element if you tell them its off a BMC J4 or Sherpa van.

Calcutt boats http://www.calcuttboats.co.uk/  of Stockton, near Daventry UK specialise in these engines and may well post stuff to you, the only problem might be the Norwegian marinisation.

There is a Dutch (I think) website that has a number of marine engine manuals on it. I think they have a BMC one - I regret I can not remember the URL, but join a newsgroup (uk.rec.waterways is a good one for BMCs) and ask them.

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If your box is the mechanical "B type" box then there are adjustments for the ahead clutch toggles and the reverse gear brake band. These are under a rectangular cover, on top of the box, held down by 4 x 1/2" AF screws (as I recall). I regret that I can not describe how to do it here - its simple enough to do, but would take hundreds of words.

The other thing is that the ahead drum on theses boxes have long through bolts. These snap, and stop gear engagement.

If I am right about the box, I seem to recall that it has a solid drive adaptor from the centre of the flywheel, rather than a "flexible" drive plate. If so, you may well need to get the flywheel drilled and tapped to accept a drive plate. You would then need an adaptor plate to fit between the new gearbox and the flywheel housing. These might be available from the gearbox supplier, or they might supply a drawing so you could get one made up by a jobbing machine shop.

Nearly any box would do the job, but I would go for a PRM from choice - if they put up with hire fleets they put up with anything!

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Everything has been sitting for 4 or more years without use until I started it the other day.

Many BMC engines smoke a bit when cold and first started after standing for a while, so there may not be any real problem, but the smoke is usually whitish (unburnt diesel).

If the engine has been standing for a while, rig up some sort of cooling system and run it for quiet a long time, gradually increasing the revs, but do not let it go much over about 2000rpm. This should give any stuck rings a chance to free themselves and wear away any rust in the bores. Also it will burn off any oil that has leaked down the valve guides, or past the pistons if the engine has fallen over at any time. Ideally the engine would be under load, but you will find that very difficult to organise.

Blue smoke is oil, so you could have oil control ring problems or glazed bores (quiet likely if it came out of a British Gas/Transco engineers vehicle). Glazed bores can sometimes be "rectified" by using a special oil, under load, from someone like Morris Oils, but you would have to get the engine loaded to try that.

Whilst the engine is out of the boat, I think the most satisfactory plan would be to send the injectors away for overhaul (Specialists in all major towns) and then remove the head & sump, draw the pistons, and glazebust the bores (rudimentary glazebuster attachments for electric drills are not too expensive). This will give the opportunity to assess/measure the bores and inspect the rings.

If this is not an option I fear you will have to marinise it, put it in the boat, and run it under load, and hope.

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We noticed when the boat was running, this rear cabin became full of diesel fumes and a 'haze' of blueish fumes/smoke was in the cabin, which we could see. This would make it impossible for anyone to be in that cabin when the boat was running as one wouldn't be able to breathe and pretty unpleasant to sleep in at night too. My partner looked at the engine and thought the exhaust gasket may need renewing. We could see no obvious oil leakage onto the engine which may have accounted for the smoking. We realise that diesel inboards are rather smoky and smelly, but this was really bad. That may be due to the fact that the engine is NOT boxed-in, but it made us suspicious. The owners never mentioned any faults with the engine and they are aware we are having a pre-purchase survey done.

Inboard diesels are not particularly smelly or smokey if they are well maintained and fuel/oil leaks rectified as soon as possible. It also helps if they are washed down once a year.

As far as I am concerned, if someone fits an engine into an accommodation area and does not properly encase and ventilate it, I wonder what other wonders there may be to find - probably expensive, and probably after you have bought it! I have a feeling that this is a very cheap craft, but even so, for goodness sake at least get a knowledgeable friend to have a look over it (if its within an hour of Reading, we will see what can be arranged). You should really pay for a survey though.

If an exhaust gasket has failed to such an extent that the cabin is filling up with fumes, you should be able to feel the gasses "chuffing" out when the engine is running - just do not get your hands so close to the exhaust that you burn yourselves.

Blue smoke is usually an indication of burning oil, but there are a number of other things to think about.
1. Narrow beam craft often have dry exhausts, if so they may also have a flexible section in the exhaust pipe. If this fails, it may be hidden by asbestos lagging (wet it right through and wear a good mask when removing and disposing of it - then refit glass fibre bandage (or an old fire blanket).
2. When the engine was in a vehicle it had a crank case breather pipe from a side cover, below the manifold, running to the air cleaner or below the vehicle. This is often just left open on shoddy marinisations. When the pistons/rings/bores wear or glaze, fumes can pour out of here. If this is the case and you have the expertise, drill and tap the inlet manifold, reasonably close to the engine, and lead the pipe to here. The only downside is that a badly worn or glazed engine - and yours sounds like it might be - could start to burn the fumes as well as diesel, so you loose control of it. I suppose it does have an inlet manifold? I have seen marinisations without them - just two holes in the cylinder head!
3. Some marine manifolds have rubber caps on either end to facilitate the use of a heat exchanger if that is the form of cooling that is required. If someone decided to fit a dry exhaust manifold, without replacing the rubber caps with welded on plates, these would burn and leak fumes.

Finally, if you do decide to buy the boat, you really should box the engine in, but make sure it can draw lots of fresh air into the case. At 2000rpm you engine will require something like just over 1000 litres of air per minute - imagine that as 1400 wine bottles or 200 oil cans in a big heap! You need at least 6" diameter ducts, and I would advise two of then.

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