Yanmar3HM35F

[daveontheway]

We recently cleaned off the rust from our engine which was mainly caused by deck leaks. There had been leaking of coolant at the bottom of the end cap on the heat exchanger at the front end. We removed same and fitted a new O ring and raw water distribution gasket inside the cap. On retightening the screws on the end cap in diagonal pairs, the cap pulled in tight against the HE body. There was some pitting in the recess where the O ring fits. On running the engine there was a weep of coolant down onto the fuel pump.

Any ideas please?

[tkeithlu]

If my memory is right from recent posts the neck to the HE cap is a press fit and has given trouble to others. The system is pressurized, so a tiny crack will leak. I think that there is a kit available.

Here's a page on it from sailboatowners:

https://forums.sailboatowners.com/th...hanger.196253/

[skipperpete]

Originally Posted by daveontheway

We recently cleaned off the rust from our engine which was mainly caused by deck leaks. There had been leaking of coolant at the bottom of the end cap on the heat exchanger at the front end. We removed same and fitted a new O ring and raw water distribution gasket inside the cap. On retightening the screws on the end cap in diagonal pairs, the cap pulled in tight against the HE body. There was some pitting in the recess where the O ring fits. On running the engine there was a weep of coolant down onto the fuel pump.



Any ideas please?

It’s a recovery job now, you need to re establish a smooth surface in the heat exchanger body for the oring to seal against. This can be done by welding, by filling with epoxy liquid metal then filing/sanding or if the surface is not too bad, by fitting a fatter softer oring. It’s important to get this joint watertight as soon as possible.
Pete.

[daveontheway]

Hi Pete. Thank you that's just what I suspected I'd have to do. The engine is probably 30 years old!

[daveontheway]

Thanks for your reply but the filler cap is not the issue I have. It's the heat exchanger end cap that's leaking.