1985 Bayliner with AQ125B Over heating problem

jayhawk36

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Apr 20, 2011
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I have a 1985 Bayliner with a AQ125B that I bought as a project boat, that I got running and seems to run good but with a little hesitation when warm. However the problem I'm having is when trying to run it wide open it heats up to about 210 or so. I have read a lot of the threads here and have tried about everything that has been suggested. The only thing I have not replaced is the hose connection on the out drive between the bellows. When hooking up a hose to the water line inside the engine compartment I know the impeller is moving but it does not want to draw water from muffs on the lower unit. The other thing the circulation pump has a leak somewhere that I can't put my finger on. It is not a bad leak but it does leak a little more when the engine warms up. I have been looking for the circulation pump online and boy are these things expensive. In fact the actual replacement part converts it to the AQ131 system which changes the heat exchanger. I have also found water pumps for the 264 Volvo Car 2.1 ltr for $30 I am wondering if that would mount up correctly. It looks the same from the pictures. Any thoughts on both issues?
 

Don S

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Aug 31, 2004
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62,321
Re: 1985 Bayliner with AQ125B Over heating problem

The only thing I have not replaced is the hose connection on the out drive between the bellows.

That is the most likely cause of your problem. The end of that hose connector corrodes away and causes an air leak. At idle and low speeds where it stays underwater, it's actually pulling water in through the leak. On plane, it's above the water and sucks air in and you overheat.

The circulation pump KIT, is 3856036 for your engine, and no an automotive carb will not replace it.
 
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