Yanmar 2GM20 Losing Cooling Fluid

[phmadeira]

hello

This morning before leaving , i checked the engine oil and cooling fluid

One of my engine, had no cooling fluid (i changed the fluid a week ago, and made one hours motor)

the expension box was full
the the "box" on the engine was empty

my oil level was a bit higher than usual, propably a bit of the fluid went down into the oil

or must have a leak somewhere

do you had this problem before ?
what do i have to check ?

thank you

[Chief Engineer]

Do you have a hot water heater plumbed into the engine?

[phmadeira]

Yes a do have a water heater plumbed into the engine?

I have two engine but the one with the water heater, have much more problem !!

what is the role of the water heater in my problem ?

thank you

[Chief Engineer]

On some applications with a water heater an air lock develops in the line to and from the heater. This may cause the engine to overheat or appear to be loosing coolant.

If your water heater is above the engine. Fill the hoses with coolant from the water heater.

[djmarchand]

Your problem could be as simple as an air bubble as another poster indicated or it could be quite serious. A higher than normal oil level indicates that coolant may be leaking into the oil. That is serious.

Fill all fluids to normal and start the engine. Leave the coolant cap (the one on the engine, not the reservoir) open. At the dock put the engine in gear, raise the rpms to about 1,000 and let it warm up. It will take 10 minutes or so to get hot.

Once the engine warms up and the heat exchanger (the one with the fill cap) is too hot to touch, look down inside the cap. If you see bubbles then that is exhaust leaking back into the engine water jacket, probably due to a blown head gasket (or much worse- a cracked block).

A bad head gasket can also allow coolant to leak back into the engine oil system causing the symptom you noted.

A definitive test for leaking coolant is to pressure up the coolant system (engine off) and see if it holds pressure. This takes equipment you can buy or hire a competent technician.

On the other hand if all you see is coolant when you look down and maybe see the level is lower than when you filled it cold, then it is an air bubble. Keep adding coolant until it stabilizes.

David