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coolant in the bilge

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scott_duerring

Regular Contributor
Occasionally I will find a pint or so of coolant in the bilge under my port engine. My coolant overflow pipe runs down there for that engine and I will notice a lack of coolant in the overflow tank. I have no issues with this engine, runs fine, temps are good. Does not happen all the time. What can cause this? I see no leak out of the cap or anywhere else on the engine so I am assuming it is coming out of the overflow tank. I keep the coolant at the appropriate line, so I do not believe I am overfilling it.
 
Check the gasket surfaces on the pressure cap for issues. Also, look closely at the HE brass contact surface for pitting.
 
2X that!

Also, pay close attention to the check valve in the middle of the 'lower' (smaller) sealing surface. if it isn't free or doesn't seal well, it can cause the issues you are seeing.
 
I re-read your post, and you mention both an overflow pipe and a coolant tank. So, you have a separate plastic tank that connects to the heat exchanger, correct? It is only 1/2 filled or less, correct?

You might consider getting a coolant dye and trace the leak with a UV source. I've seen head gaskets coolant leaks, there are also possible leak sources on the intake manifold and the exhaust manifold.
 
Yes, I have a plastic tank attached to the bulkhead which is attached via plastic tube to inlet just below the cap on the heat exchanger. The tank has an overflow pipe and is marked for levels when coolant is cold and hot... just like a auto. The weird thing about it is it doesnt leak all the time. And really never leaks alot, if I open it up at the cap the heat exchanger is full of coolant.
 
Check your cap. I had the same problem on mine - should be 7 lb cap. I had a 10 on one engine, a 7 on the other and a 15 on my genny. Changed all three to 7 and the problem went away
 
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