Yanmar Engine Coolant Fluid Capacity Puzzling

[colin_dev]

Hi,

I am in the process of replacing the coolant/antifreeze on my Yanmar 3YM30 engine. This is the first time I personally have done it on this particular engine. I am flushing multiple times with deionised water due to a change of coolant type, but that is really irrelevant to this query.

From the engine spec. the coolant capacity is approximately 5 litres and I initially drained around this amount, plus a little more from the caloifier. However, the refill only takes about 3 litres. Puzzling!

I have somewhat reluctantly run the engine a number of times, the last being for 10 minutes to see if it clears any air locks, but there was minimal drop in the fluid level in the heat exchanger. I have run the engine in idle, in gear and for a few seconds out of gear at high revs.

As I am flushing, I have now drained and refilled three times, each time only 3 litre or so goes in.

Anyone else incurred this or have a sensible suggestion on the cause.

The boat is a Jeanneau SO389 built in 2015.

Thanks. in advance.

If you respond please stay on topic.

Colin.

 

[RichardS]

If you are putting in less than you got out, then there is clearly an air lock. There is no other explanation.

If you want to flush thoroughly, then you need to go through the air-lock clearing procedures detailed in a thread a few days ago.

Yanmar 3gm30f- calorifier not working after coolant change.

I found it easy to clear the air locks in my 3YM30s but the issue may well be your calorifier which will be installed differently.

Having said all that, the only coolant change which would need flushing is when going from IAT to an OAT type but I think that 3YM30s used long-life OAT from new, so I wouldn't spend too much time on flushing unless you are getting a lot of crud out.

Even changing from IAT to OAT only needs one flush and if that's only partial it will still be fine.

Richard

 

[VicS]

Almost certainly due to air trapped in the system

Run it up to full working temperature, not just for a few minutes, and check that all the coolant hoses, with the possible exception of the return hose from the HE to the coolant pump, become hot. In particular check the hoses to and from the calorifier.

There is a very good chance that air is trapped in the calorifier, You may have to vent it off by removing the uppermost hose or even by filling the calorifier separately.

BTW if you are changing from a conventional silicate type antifreeze to an OAT type the system should be cleaned with an oxalic acid solution. Flushing with water won't remove the silicates.

 

[VicS]

Having said all that, the only coolant change which would need flushing is when going from IAT to an OAT type but I think that 3YM30s used long-life OAT from new, so I wouldn't spend too much time on flushing unless you are getting a lot of crud out.

Even changing from IAT to OAT only needs one flush and if that's only partial it will still be fine.

Richard

Sorry Richard that is wrong. Flushing with water may be Ok if changing from OAT to a conventional IAT/ silicate inhibited antifreeze but the system should be cleaned with an oxalic acid solution if changing from IAT to OAT in order to remove all the silicates coating the internal surfaces , Plain water wont do it

I dont know about Yanmar but Volvo Penta sell a " kit" containing oxalic acid for doing it.

 

[RichardS]

Sorry Richard that is wrong. Flushing with water may be Ok if changing from OAT to a conventional IAT/ silicate inhibited antifreeze but the system should be cleaned with an oxalic acid solution if changing from IAT to OAT in order to remove all the silicates coating the internal surfaces , Plain water wont do it

I dont know about Yanmar but Volvo Penta sell a " kit" containing oxalic acid for doing it.

It is not wrong. It is based on 50 years of practical experience working with antifreeze formulations from the time when OAT was not even a glint in a technician's eye. But this is not "on topic" so the OP can decide whether he wishes it to continue.

Richard

 

[colin_dev]

Vic, Richard, Thank you both for your advice on antifreeze but now I am even more uncertain over what I should do for the best. I will start another thread, perhaps you would both respond there. Regards. Colin.