Hey Guys, it's been a while! I am having a problem with the thermostat in my 90. When I replaced the head gasket back in the summer I also replaced the thermostat with an oem cummins replacement. I have to say that I am extremely unhappy with the new style and here is why. Start the truck up and drive down the road,temp starts to climb. The only thing is that it doesn’t stop until I feel that it's borderline overtemp. Has anyone else come across this? and what can I do to stop it or where can I find a good thermostat? Thanks

 

Hey bob read this
https://www.dieseltruckresource.com/...ostat+problems

 

what is "borderline" over heating? is it getting hot enough for the fan clutch to engage or is the temp gauge simply reading higher?

 

My genuine Cummins thermostat does the same thing until it opens. The temp gets up to the line that's at about 5:00, then the thermostat opens and the gauge swings a couple times before settling in the middle.

 

Not knowing there was anything special I was supposed to use, I just picked up a 180* Stant at Advance for about seven bucks.

Up hill and down, loaded or empty, zero weather or scorching hot, my temperature gauge climbs to 180 and never fluctuates from that spot for the duration of a trip.

I flattened the box and put it in my files, so I could get another like it.

 

Mine did that also, when I changed to a new one. I put the old one back in, I'm more comfortable with it. I could not pull anything with mine, had I left the new one in.

 

This is odd because my truck does that also and i did the same i went to the local auto parts store and afterwards it still climbed to 4:00 or so.?????????