Residual Pressure in Antifreeze Reservoir

[dsorrell]

I have an AQ125 with Volvo 270 outdrive. The cooling system is the kind with antifreeze in the engine trading heat with fresh water in a heat exchanger. I fixed a bad cooling problem earlier this year and it seems to be running quite well. However, I've noticed that even a day after using the boat, there is still a lot of pressure in the antifreeze reservoir. So much that if I take off the cap it still spews antifreeze fluid, even with the system totally cold. Is this normal? If not, any suggested causes?

 

[WillyBWright]

Re: Residual Pressure in Antifreeze Reservoir

It sounds like you have a well sealed cooling system. Probably an indication that you don't have a problem. Unless you don't have the right kind of radiator cap on it. There are caps for radiators with and without reserviors. There are caps with different pressure ratings (say 7 or 16 psi). I know you have a Heat Exchanger, not a Radiator, but it's the same cap. You don't need a Volvo cap, specifically. Car radiator caps of the same type and rating work too.