Hunter 336 over heating problem

[Dave]

The hunter 336 across the dock from me was overheating slightly this summer. Cleaned out the heat exchanger, replaced the impeller, checked the thru hull to make sure adequate water flow was available. All to no avail. Could the problem be in the water pump for the anti freeze mixture (internal cooling system)?Pete is worried that if he ever leaves the dock the engine will over heat.Any advice will be most helpfulThanks,Dave

 

[Bob Bass]

100% Antifreeze?

I have recently seen two boat engines slightly overheating due to 100% antifreeze in the cooling systems. One a Yanmar and the other a 650 hp Cat. Both were the result of being worked on by a "professional" mechanic charging big bucs. Should be no more than 50% for summer use, but can increase beyond that for extreme winter use, if necessary. Never 100%.

 

[Steve Dion]

Mixing Elbow?

Dave:First thing is to check the impeller to be sure that it is okay. There have been numerous reports on new ones being defective. This has been going on for a couple of years.You want him to check the belt to make sure that it is not slipping too.The next thing is the mixing elbow. This is often the problem. I posted some pictures in the photo forum on the process.As far as the antifreeze goes, the best mixture to keep your engine cool is less antifreeze. The main reason for antifreeze is anti-corrosion, water pump lubrication and freezing during the winter. I doubt that this would cause overheating in your waters.By the way, with a good friend like you, changing out the mixing elbow is much easier. It really does take 3 hands (and I heard that Pete only has two).

 

[Chris McLoughlin]

Another basic thing . .

to check is the thermastat in the fresh (antifreeze) water part of the cooling system. Remove the therastat, bring some water to a boil either on the stove or in a microwave, and drop in the thermastat. it should open immediatly. if it doesn't, change it. be careful removing the thermastat housing, if the thermastat is good, you would probably like to re-use the gasket. If you have to get a new thermastat, you should get a new gasket.Chriss/v Tidesong

 

[Andy Falls]

Sure its hot?

Are you sure it's really overheating? Maybe the idiot light/buzzer or whatever is defective and its really not getting too hot.How's the growth on the bottom? Maybe just sitting at the dock and running the motor it keeps sucking up dock trash-like a plastic garbage sack or ziplock baggy? Run it through the water some. If it overheats-take a sail. When it cools down you can motor in.

 

[Dave]

Good Idea

Pete - there is a good suggestion that to prevent overheating you take the boat out and run it to clear the bottom of debris. Also rhat you should sail it periodically. I know this means you have to leave the dock but now you may not have a choice.dave