Engine overheating

[Wm Mayberry]

I just bought a 1984 34 Hunter and picked it up last Wed. The engine seems to run fine ,except overheats when run more than 3000 RPMs for any period of time. Any suggestions as to what to check out?ThanksWm

 

[Pete]

the entire system including

water flow from seacock,stainer,thermostat,heat exchange, belts and hoses exhaust elbow.Tell us what engine it is and if it is raw water or closed cooling system so check antifreeze level and condition and engine water pump. I don't mean to overwhelm you with what to do but you need to check everthing to eliminate it as a possible problem. My gut feeling is that you may have a coked up exhaust elbow. Good Luck!

 

[jim oursler]

over heating Hunter 34, yanmar 20,heat exchanger

hello.regarding overheatingIf your boat is in freshwater, I would check the second fanbelt. ,yep, the 34 with yanmar has one belt for freshwater and a second for seawater. I am embarassed to admit that the second belt is so small that I didn't check it. If in saltwater would also check thermostat, then heat exchanger. In freshwater the heat exchanger tends to not be an issue. Regards, Jim Yanmar 20..

 

[Steve Dion]

All of these things and the prop.

William:Check all of these things that the others have mentioned. The elbow problem is not unusual. These engines need to run at 70-80% of the max RPM's. This is usually not as much a problem if you are in fresh water. You should also check the heat exchanger.Last but not least is the prop. I know that our H'31 was over-propped based on Hunters specs. Your boat (assuming a clean bottom) should be able to run the tach up to 3400-3600 in flat calm water. If you cannot get these RPM's in neutral and in gear your problem may not be the prop. If you get 3400-3600 in neutral and not in gear, I'd have the prop looked at.