omc 140 looper cooling

[largey]

HI,I am running a 1985 140 johnson in the tank under load. cylinders 2 3 4 are running about 125 degrees. cylinder 1 is running 185.Overheat alarm is not going off,there is good flow from indicator tube.The themostat looks good. Any thoughts? THANKS IN ADVANCE LARGEY

 

[ICEMAN]

Re: omc 140 looper cooling

Hi Largey, There is the possibility of a blown head gasket. You mentioned under load in the tank, Is this at high speed or low speed?

 

[jegervais]

Re: omc 140 looper cooling

Per the service manual, measure the engines' temp at the top of each cylinder head (not on the back of the head at each cylinder). After running at 5000 rpm for 5 minutes reduce speed to 900 rpm - after 5 minutes temp should be 140 +/- 15 degrees. At 5000 rpm temp should not exceed 160. Typically, the engines run cooler at WOT than at idle. Overheat switch is set for over 200 degrees.<br /><br />-John

 

[largey]

Re: omc 140 looper cooling

THANKS JOHN, I will try that.I am aiming the laser temp at the sides of the cylinders mid way between head and center of block.