Yanmar 3YM30 - Renewing Coolant

[Slipperman]

My coolant hasn't been changed for about 3 years and never by me. Once I have drained the old coolant out via the tube on the starboard side, I am guessing that I should flush the heat exchanger out before refilling? Do I just fill it with some fresh water then run the engine for a while, then drain again and refill?

 

[VicS]

There are manuals on http://www.motoren.ath.cx/

The owners manual seems to be the one that covers draining and filling the cooling system.

There appears to be a drain on the hose leading away from the bottom of the heat exchanger and another on the cylinder block on the opposite side of the engine.

Yanmar recommend the long life type of antifreeze.
If you are uncertain about the type in the engine flushing with plain water would be wise as the long life and conventional types should not be mixed. Otherwise drain from both drain points and refill with the recommended type. If the old comes out looking mucky I would also suggest a flush with plain water.

Remember antifreeze is very toxic and should be disposed of safely according to local regulations. Being sweet tasting it is particularly attractive to children, pets and other animals

 

[FullCircle]

Warning: You must use the correct ORANGE coolant as the 3YM30 heat exchanger will clog with silicates if you dont, due to having a very fine capillary.

Supply is readily (and not disastrously priced)available at any GM/Chevrolet dealer.

It is a good idea to flush out the exchanger, but also remove it first to remove any foreign objects like bits of impeller blades that retrict flow in the raw water circuit.

You may also see some level of spigot corrosion at hose ends, worth having those off and cleaning up as well.

Not a difficult job. Ensure you run a degassing cycle after fill, and top up if necessary.

 

[vyv_cox]

It is worth flushing after draining the old coolant, there is often some rusty sludge in the jacket even though the coolant contains corrosion inhibitor. You can buy flushing agents that should make an even better job than fresh water will, perhaps not justifiable in a relatively new engine, but make sure it is compatible with the correct antifreeze.

 

[VicS]

Warning: You must use the correct ORANGE coolant as the 3YM30 heat exchanger will clog with silicates if you dont, due to having a very fine capillary.

Supply is readily (and not disastrously priced)available at any GM/Chevrolet dealer.

It is a good idea to flush out the exchanger, but also remove it first to remove any foreign objects like bits of impeller blades that retrict flow in the raw water circuit.

You may also see some level of spigot corrosion at hose ends, worth having those off and cleaning up as well.

Not a difficult job. Ensure you run a degassing cycle after fill, and top up if necessary.

Any car parts supplier should have the long life type of antifreeze. Halfords certainly have both conventional low silicate types and the long-life/advanced/organic acid technology (OAT) types. They stock their own brand and Comma.

In an area where the water supply is hard or high in dissolved solids it is worth considering buying it ready diluted other wise it is preferable to dilute with distilled or deionised water

 

[Halo]

Just a thought but if you have a calorifier to heat your warm water system remember to change the coolant in this at the same time. There is a lot more collant in my warm water system than in the engine. I did not chanmge this the first time I changed it on my new boat and wondered why the coolant still looked old !

 

[Slipperman]

Many thanks for all replies, all noted. Good point about the calorifier, which had not occurred to me. I guess I just remove one of the hoses? Am I likely to get a problem with air locks when I re-connect?

 

[FullCircle]

Any car parts supplier should have the long life type of antifreeze. Halfords certainly have both conventional low silicate types and the long-life/advanced/organic acid technology (OAT) types. They stock their own brand and Comma.

In an area where the water supply is hard or high in dissolved solids it is worth considering buying it ready diluted other wise it is preferable to dilute with distilled or deionised water

Vic, you recommend what you like.
I have a 3YM30, and I matched the Texaco Havoline recommendation to the letter having had the problems with the early units. The GM spec is Texaco. It is difficult to find.

 

[VicS]

Vic, you recommend what you like.
I have a 3YM30, and I matched the Texaco Havoline recommendation to the letter having had the problems with the early units. The GM spec is Texaco. It is difficult to find.

Good.

The Texaco and Havoline long life antifreezes are given in the manual as examples of suitable products although not a specific recommendation.

I did not see any requirement to meet any GM standards