Intermittent over heating problem.

[Mike H.]

I get an overheating alarm on my 1994 Yanmar 3jh2e when I push it over 3000 rpm or when I reduce rpm to low after running the engine for a period of time.

I think the elbow is original. I boiled it out in acid about 150 hours ago. The engine has 750 hours now. Water flows out of the exhaust, but I can't say if it is enough.

Question, would you start the troubleshooting by replacing the elbow?

Thanks,

Mike

 

[kappykaplan]

You don't need to post twice . . .

 

[Mike H.]

I get an overheating alarm on my 1994 Yanmar 3jh2e when I push it over 3000 rpm or when I reduce rpm to low after running the engine for a period of time.

I think the elbow is original. I boiled it out in acid about 150 hours ago. The engine has 750 hours now. Water flows out of the exhaust, but I can't say if it is enough.

Question, would you start the troubleshooting by replacing the elbow?

Thanks,

Mike

Apologies. I posted on Hunterowners and Sailboatowners. I didn't think they would show up on the same threads.

 

[Ken13559]

The passage in mixing elbow is pretty large. You need to check that against new ones to know or search the forum for pic.

 

[JK_Boston_Catalina310]

You don't need to post twice . . .

Not everyone checks the brand specific forums for boats other than their own. I usually cross post and get completely different replies generally.

 

[JK_Boston_Catalina310]

I get an overheating alarm on my 1994 Yanmar 3jh2e when I push it over 3000 rpm or when I reduce rpm to low after running the engine for a period of time.

I think the elbow is original. I boiled it out in acid about 150 hours ago. The engine has 750 hours now. Water flows out of the exhaust, but I can't say if it is enough.

Question, would you start the troubleshooting by replacing the elbow?

Thanks,

Mike

I would also check the thru-hull. If there is sufficient growth you could get a similar reaction.

 

[Rick]

A clogged mixing elbow is usually accompanied by black smoke because it basically has heart disease. If you exhaust is below the waterline, take her out and throttle up. Look for black smoke at the higher rpm. If so, then that could be the problem. If at rpm, she is steaming from the exhaust it might be time to get the heat exchanger acid washed and flush the cooling system.

 

[celticwinds]

A lazy thermostat could be the problem. If your boat is equipped with a sea water strainer the element inside it could need to be cleaned.

 

[NYSail]

20 years is old for a mixing elbow...... I would change it. Check the heat exchanger as well.....

 

[BobM]

I assume you checked the impeller? I had never had a problem but a fin broke off and lodged in the inlet giving it reduced flow.