Yanmar 4JH3 TE coolant change

[Amun Ra]

Hello,

I have a 43DS with the 75hp Yanmar. I would like to change the coolant this year, but before I set about it, wonder whether anyone has any useful tips or advice?

Local engineer described it as a tricky job and suggested the calorifier position can contribute to airlocks in the system. I wonder what anyone else's experience of it is??

Best wishes

Julian

[j]

For the calorifier on a 36i w/ 3YM30- remove one of the engine > calorifier hoses from the engine, blow the coolant through so that it flows out of the calorifier and then out the engine drains.

Put a funnel on the hose and fill it with fresh water, blow this through and repeat until clear water comes out.
This is easier than it sounds and should be a similar procedure on your engine. Refilling is a similar process.

You might be able to drain the coolant by removing hoses from the calorifer but this won't get the crud out of the coolant return hose and it will probably be messier

[j]

Also, when refilling you'll need to take the return hose off the engine so that air can escape

[Amun Ra]

Thank you - very helpful.

That's the bit not mentioned in the Yanmar manual!

Best wishes

Julian

[j]

I should have mentioned - The dirtiest water came out of these hoses and the calorifier.

Here's some more detailed instructions: www.catalina320.com/article.php?story=20060212151611361

[Amun Ra]

Interesting that - thank you. I will set to and change the coolant this weekend.

Very helpful.

Best wishes

Julian