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318 Engine over heating

J

Jfreeman1412

Regular Contributor
Hey Guys thanks for all the help with the new boat. We got it across lake michigan today with a very few wrenching needed. Thanks again. However we ran it about half throtle for 45 minutes before we took it across the pond and everything was good. We left and got about 40 miles out and one of the engines water temp started to climb and adventually we had to shut her down and I took the thermostat out think that was doing it and that didn't do it, I then removed the hoses and made sure the impeller was pulling water and it was, would increase when I would rev it. I then ruined the gasket on the thermostat housing and had to limp it in with one motor, which was fine we threw some lines out and trolled the rest of the way. My other motor temp barley moves off of the starting temp and I verified it with a inferred heat laser, However the other one will just run hot. Right under the carb temps would sometimes reach 400+ degrees. What could be happening? I will be pulling the other hoses off the good motor and make sure the impeller is pulling the same amount of water tomorrow. Thanks for any help, This is a raw water pickup cooling system. 73 Trojan F-30 twin 318's.
 
I solved my Chrysler M360 overheating issue by removing the air pocket from the top-front end of the engine. Identify a cooling hose that is at the highest point on the engine and fill it with a 50-50 mixture of coolant-water until the level rises to the end of the hose. Cover the end of the hose until just before you reconnect it to reduce the fluid from spilling out. For my engine, this hose was from the top-side of the centrifugal water pump to the exhaust riser. I removed the hose end connected to the exhaust riser so the additional fluid filled the air pocket at the water pump.
I hope this works for you.
 
What is the standard operating temperature of the marine engines? We did find a air leak before the impeller and fix that, but now we are still running around 190 on the water temperature. Please forgive me if this is normal. We did take the thermostat out to make sure that wasn't the problem. Any help you could offer would help, we are planning on taking it back out this afternoon. Thanks a ton.
 
My rebuilt M360 was delivered with a 160F thermostat yet the engine specs call for a 170F. When running below 2000 RPM the engine temperature is about 170F and will rise to 190F above 2000 RPM.
The engine has a raw water impeller to cool the exhaust manifolds and heat exchanger for engine cooling. The front of the engine has a centrifugal water pump to circulate the coolant for engine cooling.
 
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