Yanmar 2QM20 disappearing coolant...

[partingclouds]

Aloha, Mariners,

I am in need of a Diesel Guru; someone wise in the world of mysteries, who might shed some light on why and where the coolant goes. The engine is old, (obsolete actually) but still runs like a champ. Before starting, I add coolant so the coolant level is full. After running it to the operating temperature and checking the coolant level, the canister barely has any fluid visible. Is my engine jinxed, or is there a logical explanation?

Any helpful ideas would be gladly welcomed.

Thank you in advance.

Partingclouds

[sailorchic34]

Assuming you have to fill it up multiple times, I would say your head gasket is probably toast, or maybe a hole in the heat exchanger. Does the exhaust have a sweet smell to it.

The QM series is old, but they are tanks and would run a long time with a bit O care.

[partingclouds]

Thank you, Sailorchic34. I am grateful for you wisdom and kindness.

There's no sweet smell from the exhaust, so I will look for leaks in the heat exchanger.

Cheers!

Partingclouds

[Pitchondesign]

Did you check ALL hose clamps? Some of them (on my engine) are hard to see. Over time it seems that the hoses compress and the clamps need to be tightened periodically, until they stabilize. I had this issue on my engine and generator, both 'experienced'.

[topmast]

Unless it's sloshing around in the bilge, it went out the exhaust mixer. Likely the HX is toast due to not changing zincs often . If it was a head gasket leak you would overflow the canister with bubbles. Pressure test at a rad shop .and the offending tube can be plugged with cedar dowels .(a get home solution but been there)