Cooling Issue..

[Cale22]

Hey all,

Basic info:

ford powerstroke FMIC
almost new radiator
160 thermo
ramchargers dual fan

For some reason, anytime I hit highway speeds my coolant temp. is around 190-206, and when I begin to slow down, my temps drop to around 175-180. I know that these are common signs of a stuck open thermostat, however I've watched the temps at start up: It takes a while to warm-up, but once it hits 165-170 it drops down to 150-160 and then begins to rise up again. Any ideas on what could be causing this?

 

[FlyinGN]

are all 4 sides of the radiator 'boxing' diverters(for lack of better words) there so that all the air the comes thru the grill is going thru the radiator and not around it? Most cars with front mounts have the bottom one removed for clearence for the ic pipes..

 

[mark b]

Air in the system maybe? You could try that old trick of drilling a very small hole in the thermostat to bleed it out.

You could take the thermostat out and check it in boiling water to insure it's opening correctly and evenly.

Depending on your gauge and sensor location, the readings can vary. I know VDO units are 5-10 degrees off.

I'd also suggest getting some RMI-25 in there to clean out any deposits in the block and heads.

Good news is your are not overheating!