heating problem D2-40 Volvo

[Alec]

Hi All,
I have only just bought a Bavaria 40 and on my first trip out had a problem with the engine overheating, I changed the water pump and give the engine a complete service only a couple of weeks back. there is no oil in the water or water in the oil there does not appear to be any problems with the sea water side so I am assuming there is a problem with the heat exchanger or thermostats or engine water pump or exhaust elbow. Can anyone tell me what is the most common problem with regards to overheating ?
Alec

[Moodymike]

Most common problem is the exhaust elbow blocked.

[IslandAlchemy]

Is there water coming out of the exhaust?

If not then check through your seawater system (seacock, strainer, impellor, exhaust elbow, etc.)

If so, then start checking your coolant system (water pump, thermostat).

I doubt you have a blocked heat exchanger.

Also put an infra-rad thermometer onto the pipes and measure the coolant temperature. It might be a faulty sensor.

[Odysseus]

If your raw water system is working OK then the common denominator is the heatexchanger. When the service was last done was the impeller in one piece? As parts do break off and clog up pipes in heat exchanger. Heat
 exchangers do get clogged. Also has the water ever been flushed and changed, read my note about drain bolt, there is not a tool to undo it, so the job is not done, even by service engineers.

Its a messy job but back flush the system to assess the flow and if any rubbish comes out.

Thermostat is another option take it out and and run engine check, the sensor can fail and call the alarm.

It's a slow check through until you find it.

Odysseus

[Alec]

Hi All,
Thanks for the reply and suggestions, here is a couple of answers to some questions.
yes there is water coming out of the exaust like normal I think, water comes out then stops for a few seconds then comes out again, when the engine started getting hot there was also like a mist/steam coming out as well and that is what alerted me to the problem as I did not hear the alarm until I reduced the revs. When I changed the sea water pump impellor the old one was still in relativly good condition with only a small crack, when the engine is running I can see the sea water through the pipes and all seems normal. the engine has only done 849 hours which I would not consider a lot. I dont think a faulty sensor due to the steam/mist and I lost about .5 of a liter out of the expansion tank so it obviously got hot.....apart from this problem it runs nice and smooth and starts first click. Welcome any more suggestions

[Ripster]

Like others, I agree its going to be a process of elimination.  On the Raw water side, seacock correctly open, pipes not blocked or kinked, impeller working correctly (I agree with others that if a past imp has broken up and there are bits in the system, one of these pieces can move to block flow.  Powerful back flushing will clear this) heat exchanger or raw water filter not blocked - exhaust lines all clear.  After this - check your fresh water side in the usual ways.  If you are getting steam from the ex pipe, then things are getting a bit hot by the sounds of it.  If you get a laser thermom, the temp of water at the exh is not normally more than about 40ish deg prob less.

[Stuart]

Hi we had the same issue 2 weeks back steam but much reduced water flow. Impeller was good but we noticed a bent hose (Bavaria went a little cheap on these) and it was starting to crimp the flow that didn't totally solve the problem so the mechanic flushed out the leg through the intake line to the strainer and all is well 

[Alec]

Hi All,
Thanks for some good feed back.
The yacht is at Marmaris (Turkey) and I am hoping to go down this Saturday and will try everything suggested.
I will let you all know the results on Monday, I will be taking with me a thermal image camera as well so will be able to look at everything (hot spots) with the camera
Thanks to all
Alec

[Alec]

Hi All,
Update
I had Volvo have a look at the engine during last week and there report said a restriction caused by something wrapped around the leg or air getting into the system could be the problem, they could find nothing wrong with the engine and said everything was good  , I dived down on Saturday and there was nothing restricting flow like a plastic bag so I run a hose through and backflushed the system for about an hour, after that I removed the filter cap and checked the strainer and when putting the filter cap back on realised it was not seating properly and it took several attempts for it to screw on without being cross threaded, I then took it out and run the engine for several hours with no problems. On the Sunday I went out again and run the engine for a couple of hours and all was good until I come back to the Marmaris marina and had to wait for half an hour for a birth, during that period of low revs or just idling the alarm come on a few times  but increasing the revs slightly for a few seconds would silence the alarm, i will check my idle rpm's on Saturday though I think the problem could be restrictions in the leg like rubbish or barnacles. i will flush again and see how it goes and let you all know.
Regards,
Alec

[solar]

Been there with the steam joy...
The OEM VP raw water filter housing is made of too many parts/gaskets which will leak air sooner or later!
Take a good look at it if not letting air into the system.I'm almost sure that you'll find the answer there.
In my case I had to replace it with a new one after 400 hours only.
Next one won't be a VP!

[Rampage]

From the symptoms you describe, it would appear to be a raw water problem.  When you removed the impeller, were there score marks on the inside face of the cover plate?  If there were, this will significantly reduce the effectivness of the pump and lead to the sort of problems you describe.  I had the same problems and replaced the original plate with a Speedseal Life and sorted the problems completely.  Speedseal are here: http://www.speedseal.com/SpeedsealLife/SpeedsealLife.html