Bavaria 38 engine cooling problems

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iainbluk

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I have a 2003 B38 which I have owned from new but have recently had a problem with the salt water cooling side of my engine which is a Volvo D2-55. At idle revs it kicks out a decent ammount of water through the exhaust and all seems well. However as the boats speed and engine revs are increased the water being ejected from the exhaust progressively reduces and steam/water comes out of the exhaust. The engine is not overheating at this stage according to my temperature guage, but the exhaust seems to be. The steam is definately that, having smelt it, it is not unburnt fuel. There appears to be air getting into the system somewhere, as bubbles can be seen in the clear pipe that leads from the heat exchanger to the exhaust elbow. The exhaust elbow does not seem to be blocked as the pipe from the heat exchanger is not under pressure whilst the engine is running.

The engine has done about 550 hrs

So far I have
1) Replaced the impellor
2) Replaced the water pump seals
3) Replaced the seals on the bottom of the raw water filter pipe inlets
4) Replaced the filter basket and seal
5) checked the leg inlet is not blocked when it was lifted last week including rodding up the leg to remove any possible crustacean blockage.

Has anyone else had or heard of this problem? I am at a bit of a loss as to what to do next.

Thanks
 
Rather than try random solutions (a natural human trait) get hold of this if you haven't already got it.

http://www.scribd.com/doc/36293690/7745858w-D2-55-D2-75-OPERATOR’S-MANUAL

Then test, using a bucket and freshwater pipe -

1. coolant direct to raw water pump - if the problem ends there, the air is being drawn into the filter unit - having had the problem previously I found the only way was to replace the whole unit.
2. if it still persists the pump-body may be worn, take it out and have it properly serviced (it might need re-machining or a new faceplate).
Unless you are mechanically adept, I'd recommend you don't try #2. and check it yourself.

At 550 hours your engine has not done anything like any work - my 5 year old yanmar has done 1857.9 and the one before did >10,000.

If it is, as diagnosed by you, lack of raw-water throughput that should put the matter to bed.
 
Have you checked the hose between the pump and the intake sea-cock? If that is collapsing under the suction of higher revs the results might be as described. It should be wire-reinforced or similar and when that wire rusts away (especially close to clamps and fittings) the hose can simply collapse on itself.

Otherwise if it pumps water at low revs there's little I can think of but exhaust back-pressure to prevent it from flowing faster at high revs - is the exhaust elbow choked with exhaust deposits - or possibly corroded away inside? Removing it to check may be an awkward job but the only way to find out.

Others more familiar with this particular engine may advise, but first examine the hoses that are under suction at high revs for flattening and collapse.
 
Thanks for the suggestions Charles. Ive got the manual. I have tried to go about fixing it in a ordered manner which is why I replaced the items in the following order..impellor, filterbasket, seals on the inlet pipes, water pump impellor and seals. Effectively the water pump had been overhauled. Unfortunately the water draw is too great to use a bucket when the engine is running above idle..it empties the bucket in about a minute! I think my next step will be to bypass the inlet filter temporarily and see if that increases the water flow at speed. I have checked the elbow in the fashion advised by French Marine, ie squeeze the pipe just before the elbow when the engine is running..if there is a blocked elbow it will feel pressurised, which it doesnt! Also the inlet pipes to the pump are not collapsing under suction.
charles_reed said:
Rather than try random solutions (a natural human trait) get hold of this if you haven't already got it.

http://www.scribd.com/doc/36293690/7745858w-D2-55-D2-75-OPERATOR’S-MANUAL

Then test, using a bucket and freshwater pipe -

1. coolant direct to raw water pump - if the problem ends there, the air is being drawn into the filter unit - having had the problem previously I found the only way was to replace the whole unit.
2. if it still persists the pump-body may be worn, take it out and have it properly serviced (it might need re-machining or a new faceplate).
Unless you are mechanically adept, I'd recommend you don't try #2. and check it yourself.

At 550 hours your engine has not done anything like any work - my 5 year old yanmar has done 1857.9 and the one before did >10,000.

If it is, as diagnosed by you, lack of raw-water throughput that should put the matter to bed.
Click to expand...
 
I have a similar issue to you with my D2-55, and have been unable to track down and solve the problem. Please let me know if you find the solution to your problem.
 
Hi Nigel,

Yes fresh water circ seems ok..engine operates at normal temperature, probably because water is so cold at the moment, so lack of cooling water to the engine is not an issue..the exhaust is a different matter I suspect. Impellor is driven by a engine drive, not a belt.
nigelmercier said:
Are you sure they are air bubbles, and not pockets of steam?
Can you see the inlet to the heat exchanger?
Impellor belt slipping?
Fresh water circulation OK?
Click to expand...
 
I cannot say that I understand your symptoms but, as a known weak point on this engine and being unsure of where to look next, I would inspect the exhaust manifold for salt blockage. After that look at the upstream side of the heat exchanger.
 
Just to add support to the two posts above, historically when everything else has been checked it always seems to be a problem with the elbow. Cruds up ... restricts flow.

It became such a regular post that I actually took mine off my 2020 engine as preventive maintenance and it was fine.

Not sure if it fits with your symptoms but on older engines people suffer from collapsed inner walls on the rubber exhaust pipe.
 
Nige,

I havnt physically checked the elbow inside, but as I said in a previous post, French Marine at Titchmarsh suggested that if there was no back pressure to the exhaust elbow, indicated by being able to squeeze the pipe to the elbow whilst the engine was running that it should be ok. Havnt taken itoff yet because of that and also because the problem appears to be air getting into the systemm before the elbow. Having said all that, if the pump and upstream of that has all been checked it only leaves the elbow and the exhaust (and perhaps the heat exchanger)
nigelmercier said:
I asked about that, didn't get a reply.

Cleaning out the exhaust elbow you may find stuff that looks like metal, but is crud. I ended up sticking a screwdriver through the side, better to discover this while not at sea.
Click to expand...
 
Air getting in can only come from upstream of the pump. Downstream the whole system will be at pump discharge pressure, not normally very high because it is open ended, provided the manifold is not blocked, but certainly higher than atmospheric. If you have checked everything upstream of the pump for leaks, and provided that the pump is not excessively worn internally and the impeller is the correct size, then it is not air that you can see.
 
If your cooling water comes in via sail drive I would check that you do not have a family of mussels in there stopping the flow of water I had same problem and cured it by removing pipe from seacock on leg,and with valve turned on poking a wire coathanger (straightened out) down it. you do get water in the boat but it is better than having to dry out.
 
I know you've checked it, but I would always be suspicious of the rubber joint on the top of the strainer bowl. Guess why I say that. Mine had stretched, and let air in, even when well smeared with vaseline.
 
Worth checking the cap on the inlet filter both for cracks and that it is fully seated. It only has to be slightly loose to let air in particularly at higher revs. If you have a translucent hose from filter to the pump you will see the bubbles. Other things to check are the heat exchanger end caps for debris and as already suggested the exhaust elbow.
 
Thats my problem.(replying to vyv_cox) As you can read from my earlier posts, most of it upstream has been checked. The fact that the bubbles (assuming thats what they are) in the pipe downstream of the heat exchanger get more as the throttle increases tends to suggest air leakage into the system, I just cant find the source! I think it must be the seawater filter but as I said earlier ive already changed the bottom gaskets and the filter basket/seal. One of the problems with the volvo system is that the hose from the seacock to the filter is a different diameter to that going from the bottom of the filter to the engine pump so getting a replacement filter is not straightforward as most have the same diameter inlet/outlet. Ah well,I cant go sailing in this weather so at least I have time to get it sorted, and thanks everyone for the suggestions. I was really hoping to find someone else who had the same problem who had effected a fix, and one guy has said he has the same problem but also hasnt managed to fix it yet.
 
Last edited:
Force 4 have a water filter with stepped spigots that will allow different size hoses for inlet and outlet. Page 62 of catalogue. On my Bavaria the filter is mounted on the aft bulkhead and a bit tricky to get the lid on properly. It is easy to cross thread or not screw down properly. Last time I cleaned it I did not tighten it properly and got air in. It only needed less than a 1/4 turn to stop the air bubbles. Also worth checking the hose clamps as again if they are not absolutely tight air will get it. BTW have you checked and cleaned the anti syphon valve and ensured it is seating properly?
 
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