I have twin volvo Tamd40 diesel engines 165 hp . The starboard engine is useing a lot of water about half a pint per hour use. I can't see any leaks but the water seams to come out under pressure from the filler cap , when under way. Don't tell me its the head gasket! Water filters are clear any clues?


New member
21 Aug 2001
Northland New Zealand
Okay then I wont tell you that its the head gasket.An
alternative could be the heat exchanger needing a cleanout.Is the water being forced out by the overheating or by pressure from a cylinder? Sometimes a head gasket shows bubbles puffing up when the cap is removed. (only check this when cold to avoid the risk of burns.)The thermostat could be the problem and is probably one of the cheaper parts to replace.Try swapping filler caps just in case .Check that pumps are working ok .
Lets hope it is one of these more minor things, but beware of running an overheating engine as your problems could go from minor to serious fairly Quickly.
Good luck!


Active member
4 Jun 2001
Mark, I recently had a problem with water coming out of the header tank. It turned out to be a failure in the heat exchanger which allowed sea water to pass into the fresh water system when the engine was running and then the system overflowed. After the engine has been stopped a while the header tank level drops (provided the seacock for the raw water is left open) . Unfortunately the heat exchanger from volvo for a 2003 engine costs £500+vat! so I have had the failed core stopped up just now till I find a cheaper supplier. Of course you may not have the same problem, hope this helps.


New member
16 May 2001
Bungay, Suffolk
I have had the same problem and it was the heat exchanger allowing salt water into the cooling circuit. Unfortunatly the heat exchanger matrix is not simple tubes but more akin to a car radiator. They are very difficult to get out of the housing but it can be done with care. after I had struggled and cursed aand finaly got it out (with just a little damage) I had a brainwave and realised that had I fabricated /bought a flat large based handle I could have fitted it to the matrix with hot melt glue and gently pulled it out of the housing. You will see what I mean if you take the end of the housing. Unless yours are the b series engines in which case ignor the above cause I think the cooling system was different.
Two options (unless you want to go the Volvo £££££££'s route), a) remove the matrix and take it to a car radiator repair shop - they may be able to fix it, b) phone Paul Grieve at Coastal Rides on 01303 262300. He sent me a recon exchange unit and may be able to help. Dont know the price though as mine was done under warranty from the broker. Further advice freely available from www.Boatdiesel.com
Hope this helps.


Well-known member
30 May 2001
You don't say whether the engine is over heating. If it is I also had this problem some time ago and changed the head gasket twice before the real problem became apparent - I had a hole in one of the cylinders! The only cure was a new engine. The symptoms were a constant blowing out of the water from the header tank and overheating from about two thirds revs onwards.

Hope this isn't your problem, from above posts I would check all the easier things first such as the heat exchanger etc .

Best of luck!