My wife an I have a 1986 44' Gibson with 270's or 350 GM's. I have checked everything I can on my starboard engine, but can not get enough water to run at the proper operating temptures.The engine runs OK at low rpm's, but @2000 rpm range the engine starts to run hot. Here is some background on the engine. This engine was rebuilt in 2004 after scoring a cylinder wall from over heating. After installing the rebuilt engine I have replaced all plumbing and hoses on this engine as well as the fresh water impeller. However, it continues to run hot at average rpms for cruising. I hope someone else has had this problem and might be able to help me with this issue. Thanks, Don

I am not very knowledgable, but I will offer my input.



Does your engine have a water pump on the front of it? If so, have you replaced it or done a flow test? Have you checked or replaced your thermostat?

If the previous engine also had overheating issues, what components, external or internal have, been used on both engines? What do these engines have in common?

I am sure that others on here have more/better ideas, but this is a start in troubleshooting. I hope this is of some help.

Thanks Hank: You make a good point about the water pump, it is the same pump, and has not been checked. Thermostat is new. Can you tell me more about a flow test ? I know how I would do it, but I would like to here what you think. Thanks Don. Lake Barkley Ky.

Plugged risers, pieces of old impeller partially blocking part of the circulating system, grill on water pickup partially blocked, sand in the water passages around the cylinders. internally collapsed exhaust hoses, air being sucked in around intake filter fittings gaskets or pump shaft seal, too much spark advance, lean carb, etc, etc, etc

Invest in a heat gun and put it to work.

Run it, pull theplugs and look for differences.


OLD HOUSEBOATER39120.8125231481

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OHB,

Heat gun? Please explain to this old dummy. Thanks!

Infrared thermometer.