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      On my Bavaria Holiday 35 I have a Volvo 2930 engine which has served me very well since I bought her in 2003, however recently I have found I need to top up the coolant level in the heat exchanger every time I use the engine, even if I only use the engine for an hour. The problem is I have no idea where the coolant is going as I is not around the engine, and even though I have installed a thermostatic valve in the hose that leads to the calorifier to try to reduce the temperature of the hot water, I still get a discharge from the calorifier due to hot water expansion, but only when the engine is running. I do not get hot water expansion if using the immersion heater when on shore supply. So has anybody else had this problem or know the solution?

      Ed Holmes


      Hi Ed

      It’s got to be either:-

      1./ Going into the engine (head gasket, heat exchanger chorosion, etc.)
      2./ Going into the bilge (leaking hose etc.)
      3./ Going into the raw water (hole in heat exchanger tube, leaking o ring, etc.)
      4./ Header tank cap not sealing properly (coolant can escape when hot and then vapourises)

      Try No.4 first (get a new heat exchanger cap & seal).

      If that doesn’t sort it, my bet would be No.3

      The collant system is sealed and works under pressure, so the tiniest hole anywhere is going to cause coolant loss when hot.

      Whichever it is (if it’s not No.4), I reckon you’re probably going to have to get the heat exchanger off and get it pressure tested. If it isn’t leaking, then get new O rings and gaskets from Keypart, and put it all back together, tighen-up all hose connectors, and see if that fixes the problem. If it doesn’t then it’s probably going to be No.1.

      Best of luck



        If you’re losing coolant with on external sign of water loss it’s most likely to be head gasket failure.
        Had the same problem with a Nissan truck on a booze cruise to France.


          +1 vote for number 3


            One or Three for me πŸ˜€


              Replaced heat exchanger cap and it seems to have cured it, thanks to you all

              Ed Holmes


              Excellent news Ed.

              It’s usually something simple, but all manner of horrors go through your mind.

              I had a similar problem, and after a so-called “marine engineer” telling me that it was probably a head gasket or cracked head, I stripped the engine, found nothing wrong, and then discovered that it was the Β£4 seal on the heat exchager cap.



                Glad your sorted!

                Remember what they say about experts;
                X is an unknown quantity, a spurt is a drip under pressure!

                πŸ˜€ πŸ˜€ πŸ˜€ πŸ˜€

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