Coolant in bottom of engine and safe mode

[chefojfc]

I have Yanmar 4JH57 engine and on a couple of occasions after a long motor run, coolant appears in the bottom of the engine compartment.
I checked the coolant level and it is above the top line of the reservoir.
Additionally on this run I had a "Chk Eng" alarm that put engine into safe mode.
any thoughts?

[Pete17C]

Originally Posted by chefojfc

I have Yanmar 4JH57 engine and on a couple of occasions after a long motor run, coolant appears in the bottom of the engine compartment.
I checked the coolant level and it is above the top line of the reservoir.
Additionally on this run I had a "Chk Eng" alarm that put engine into safe mode.
any thoughts?

Isn't is supposed to be between the lines? If is over filled it will expand beyond the capacity of the reservoir.

Don't know about the Chk Eng alarm.

[Calif.Ted]

Did you also check the level in the heat exchanger ? Yanmars can be very particular about the cap used on the exchanger and the outer lip doesn't quite seal. When the coolant expands a little it leaks around the cap instead of into the reservoir.

[Shrew]

+2 on check the heat exchanger. It should be at the cold level (lower line) when cold. Was the engine hot or cold when you checked the reservoir?

[Jackz]

I had this happen to me and it turned out the hot water heater was leaking back into the cooling system, causing it to build pressure and escape through the overfill reservoir.

[Halien]

This happened to me on a Universal 5424. Turns out the heat exchanger had a tiny leak. It was almost imperceptible to the eye, but bubbles were easily spotted when we pressure tested it in a tub of water. My oldest son is a plumber, so he took it to his shop and brazed the hole. Problem solved. This had been driving me nuts for months. It was a pretty simple repair.

[Capt. Hack]

There may be two bleeder valves one by heat exchanger and one lower on the other side. . I had one vibrate open lost all my coolant

[Djarraluda]

Originally Posted by Jackz

I had this happen to me and it turned out the hot water heater was leaking back into the cooling system, causing it to build pressure and escape through the overfill reservoir.

Plus one for this. It was my calorifier that was leaking when I had this. Antifoul in the bilge is also a bugger if the gas sensor gets wet, check it works still
Roger