Yanmar Heat Exchanger Problem?

[AlanBrown]

Recently experienced a problem with my 1981 Hunter's Yanmar 2GM. Here's what happened.

Started engine and only got 1/2 the normal flow of water out the exhaust. Checked raw water inlet and strainer. All clear.

Noticed stream of warm water flowing out of engine compartment into bilge, but engine ran fine.

Water stopped coming out with exhaust. No exhaust either. Engine compartment got quite warm.

I suspect that the heat exchanger finally bit the dust. Your thoughts and suggestions.

Boat is back in the Bahamas, so I can't do any personal troubleshooting from here.

Many thanks!

[Faster]

A number of things come to mind...

Your water line to the mixing elbow may have come adrift...

Water pump failed (possible overheating)

Heat exchanger plugged badly, as you suspect.

Not sure what you mean by "no exhaust either" - while engine was still running??? Inside the boat was hot, was it fumey too? Could you smell exhaust gases down there?Is the exhaust hose from the water lift to the outlet intact?

Sounds nasty....

[lbdavis]

It could be the mixing elbow itself. These corode and need to be replaced fairly often.

[beej67]

Originally Posted by AlanBrown

Recently experienced a problem with my 1981 Hunter's Yanmar 2GM. Here's what happened.

Started engine and only got 1/2 the normal flow of water out the exhaust. Checked raw water inlet and strainer. All clear.

Noticed stream of warm water flowing out of engine compartment into bilge, but engine ran fine.

Water stopped coming out with exhaust. No exhaust either. Engine compartment got quite warm.

I suspect that the heat exchanger finally bit the dust. Your thoughts and suggestions.

Boat is back in the Bahamas, so I can't do any personal troubleshooting from here.

Many thanks!

If the engine's not overheating, it's probably not the heat exchanger.

Sounds to me like the hose between the heat exchanger and the mixing elbow came loose. I'd check that first. Second thing I'd check is carbon buildup in the mixing elbow itself. Third thing I'd check is to see if your muffler's leaking.

Check the easy stuff first.

Hate to sound snarky, but have whoever's got your boat crank it and look in the compartment to see where the water's gushing out of. Chances are that's the source of the water.

[AlanBrown]

BJ,

You didn't sound snarky.

I crawled down into the quarter berth with a flashlight and couldn't see the source of the leak. If I had more time my next step would have been to empty out the cockpit storage locker and try to fit my 6'2", 300 lb. body down into that small space to take a look from a different angle. Thank goodness I had a ferry to catch to Green Turtle Cay!

Now grabbing some overtime hours to pay some skinny dude to crawl down in there and fix things. Self-reliance has it's limits. Money doesn't.

Thanks for your suggestions.

[beej67]

I missed this part earlier:

No exhaust either.

If there's no water and no exhaust and your engine compartment is getting warm, then the pipe to/from your muffler, or the muffler itself, is broken/loose. Or the pipe between the mixing elbow and the radiator has come loose, and the exhaust is coming out that. By hook or crook you've either got a loose hose, or a busted muffler, and the stuff that's supposed to be coming out your tailpipe is discharging freely in your engine compartment. That's good news, because a loose hose is free to fix, and a busted muffler is cheaper than engine parts.

From personal experiences, mufflers are a major pain in the rear to fix, and hiring someone is a great idea. It's a real simple issue, congratulate yourself on diagnosing the problem, and have a beer while someone else fixes it. Particularly if the boat isn't where you are. But it could be something as simple as a hoseclamp come loose, so if you can't fit down to fix it, get your wife to do it. Might save you some labor.