C12 Idel OVerheat

[Steve Huber Co-Admin]

Engine / Tranny going to overheat when idling either in gear or neutral. Soon as I start driving and increase fan speed/airflow, temps drop quickly to normal. Suspect fan speed problem. Anyone else ever have/fix this problem?
Steve

[Tom and Pam Brown]

Steve,  it sounds like thermostat may be frozen closed.

[Steve Huber Co-Admin]

Tom,
Thx for the input. Wouldn't a stuck thermostat drive temps higher during cruising also as flow would be severely restricted??? Temps appear normal, even when climbing hills (but haven't hit any steep ones since problem occurred).
Steve

[Edward Buker]

Steve,

Try shooting the face of the radiator in a pattern with an IR gun when you first stop. Continue to shoot it in the same pattern as it goes into overheat during idle. See if the whole face of the radiator stays stable temp wise or climbs in temp with the engine overheat. If it climbs and is uniform with the block/thermostat housing I would think air flow. If the radiator is non uniform, antifreeze flow may be restricted within the radiator. If the block is running hotter than the radiator then possibly the thermostat or the water pump is malfunctioning and you have a flow issue. You should also check for a pinched or collapsed hose at idle that could expand with pressure and flow. It would be best to take these measurements on a known good coach and see where the differences are but you may be able to sort this out on your own if the information points you to the source of the problem.

Later Ed

[Steve Huber Co-Admin]

Ed,
Good inputs. Will run checks.
Thx,  Steve

[Edward Buker]

Steve,

I have not had to do these measurements on the C12 but I did do them for the genset and this type info was helpful in sorting out what was causing my genset to overheat. It certainly was a really good method for confirming the cure. Someone with more diesel engine and cooling experience may be able to chime in with some pointers along the way. Good luck...

Later Ed