Changing coolant in Yanmar 3YM30

[reverie]

Hello all,

Every two years I replace the coolant in my Yanmar 3YM30 engine. After draining the old coolant, I very slowly pour in the new stuff until full. However, inevitably I am left with an only partially filled engine. Until the thermostat opens, it seems the new fluid can't get into parts of the engine. Then when I run the engine for a while, the temperature alarm goes off. After I stop the engine and let it cool, no problem topping off the fluid. Is there a trick to this, or a better way of doing this?

Thanks

John

[On y va]

There are plastic coolant drain tubes on the side of the engine?? Open them till coolant comes out. Then shut. Then top up coolant, till the correct amount has been added (see manual).

Also, do you have a boiler/calorifier connected? Open the bleeder nut and run the engine (at some revs) till cooland comes out.
Best to do this with two people.

[reverie]

Many thanks, Onya. I will try this approach later this week.

[Jm621]

I am also getting ready to change the coolant (first time doing this) and it appears as though the Yanmar manual says to fill the coolant/ heat exchanger first and then add coolant to the coolant recovery tank directly (if not at the full line). Am I interpreting the manual correctly (see attached photos for corresponding pages from manual)?

Thanks,
Jon


  

[reverie]

Yes, that's definitely the right way to do it. I finally got it working well. Key is to fill the engine very slowly. Also squeeze the large hose in front of the engine a number of times after the engine appears to be full to squeeze out air bubbles.

Good luck.

[no3l]

Hi All,

I am in the process of replacing the coolant on my 3YM30 and have a couple of questions I hope can be answered.

1) How do you drain the coolant from the hot water tank/calorifier? I have drained the engine and heat exchanger etc but cannot see any easy way for the tank.

2) What is the purpose of this fitting on the tank? Is it a drain or a input?



Attachment Deleted

Thanks in advance.
Noel

[Xantia]

Hi All

I bought a packet of coolant test strips and check the coolant every year. If the glycol level is enough and the corrosion protection is good, why change the coolant. You don't do it for your car do you? This is a case where the maxim "If it ain't broke don't fix it" works for me.

Cheers

Ian

[reverie]

Noel,

I must admit, I didn't bother with attempting to drain the coolant in hot water heater hoses. I figured this would not be a big deal, since I change the coolant every two years - in line with the instructions in the manual.

John

[no3l]

Hi,

I found another thread on the forum which suggested the following method.

There are two hoses going from the engine to the calorifier, remove both and blow through one hose, using a suitable container to catch the outflow from the other. The amount is not much approximately 1 litre. Once the coolant was drained I rinsed the tank with fresh water and then primed it with fresh coolant before refitting the hoses.

It was a very easy operation, the only problem was getting the hoses off the engine, they were a really tight fit.

Regards
Noel