I just replaced my radiator a few days ago. When I was driving to my new place the truck was making a funny noise. Kind like when a truck is over heating and the fan kicks on. It only lasts about 2 min. or so. Then I got to looking @ my temp gauge. It was not changing temp. from, 145-190 it just stays @ 190 and does not move while on the high way. I was wondering if this might be the thermostat? Any idea. Thanks again -Anthony

 

What kind of noise are we talking about?

 

Like a fan roar. It happens every few min. and olny last like a min. or 2. I have not driver the truck with the ac of yet to see if that might have something to do with it or not. I have never heard it before but latley I have not been playing the radio much so I kinda wonder if it is normal and i just never noticed. It is not real loud but you can tell when it does it. But I am going to replace the thermostat tommorow to se if my temp. goes back to normal. Thanks -Anthony

 

From your description it sounds like your fan clutch is engaging and releasing. That should be normal. Holding the coolant temp at 190 is not normal for an OEM thermostat. I would get the new improved thermostat from Cummins and swap out the old one.

 

in this 100+ degree weather mine does this all the time. RCW is right. I get lots of fluctuation out of my factory temp gauge. Will sit at 190 for a few seconds, then should drop down to 130, then slowly bback up to 190. This is what they normally do.

 

I put the new thermostat in and the temp. is back to normal. I guess I just never heard the noise over the radio or the engine before. thanks again -Anthony