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Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3870
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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I installed a rebuilt universal M-40 (32 h.p.) engine two

Customer Question

I installed a rebuilt universal M-40 (32 h.p.) engine two years ago. At first all was well. Then it started to overheat if used above 2350 rpm. I live in the Florida Keys, so the raw water will always be warm (75-90 degrees F). I have flushed the system repeatedly, installed a new raw water pump, checked all hoses, am in the process of cleaning the heat exchanger (an hints welcome). Will check all hose fittings, again, when I finish with the heat exchanger. Is there anything else I need to do? Also, there is steam coming from somewhere on the block and I have not detected a leak. Any advise most welcome. Regards, Andrew.
JA: Sometimes boat issues seem like they'll be really complicated, but end up being easy to fix. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. Is there anything else the Marine Mechanic should be aware of?
Customer: I don't believe so.................
Submitted: 1 year ago.
Category: Boat
Expert:  Charles replied 1 year ago.

Hello, my name is***** will assist you.

Expert:  Charles replied 1 year ago.

You are on the right path with the heat exchanger, I would also recommend that you add a dye to the coolant on the engine so that when there is a leak in the coolant, you will see it glow under a black light. This works really well in leak detecting, and this leak may be the cause of the overheating.

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