Yanmar 3ym20 coolant leak from heat exchanger

[matt1]

Hi All

I've removed the end cap off the heat exchanger on my 3ym20 to clean it up and paint it. In so doing I exposed the element (which I assumed just filtered sea water) but this seemed to leak coolant whilst the end cap was removed. In fact now I have replaced the end cap, including a new seal, there still seems to be an accumulation of pink coolant in the bilges even though the engine hasn't been run. Any ideas? I can't find any obvious coolant leak from anywhere else. I assumed the coolant and sea water circuits would be entirely separate and there should be no coolant with the raw water???

Engine is 10 years old but only 500 hours

 

[RichardS]

There are two rubber sealing O-rings at either end of the heat exchanger, one stops the seawater from escaping and the other separates the seawater from the coolant.

It sounds as if you have broken the seal on the outer O-ring but also dislodged the seal on the inner O-ring thus releasing some coolant. They are held by the same end cap bolts.

If it all nips up OK and there are no more coolant leaks you should be OK. If you have dislodged the inner O-ring such that it is not seating correctly it will continue to leak and you will have to re-assemble it.

Even if it is not leaking coolant into the bilges it might be leaking into the seawater outflow so you will need to keep a careful eye on the coolant level.

Richard

 

[matt1]

Great, thanks Richard. I'll take a look at this next time I'm at the boat

Matt