...or just opening prematurely?....Ok, so I dont have access to a temp gauge so I'm taking my readings with a meat thermometer....however, its impossible to get consistant heat into my cab right now....running without a fan and blocking the outside 5" of the rad with cardboard, it takes a while and a hill to get the gauge to where my thermometer in the rad will read 180....with it idling high, warmed up but not hot until I hold the rpms, I can get the thermometer to get from 150 to 180....
Now, when I start it dead cold, there is no temp change or fluid movement in the rad, which tells me that the tstat is closed, however, once its warmed up and the tstat opens, when I park it and let it cool down until the block temp (read through the 3/4""plug above the tstat) goes down to 110, it appears that the stat is still open....
1)I can move fluid through the block with the upper rad hose
2)If, with the 3/4"plug removed, I take the rad cap off, the system bleeds off through the plug....
3)with the engine reving, I see a temp change and fluid drop in the rad...
Its not a cummins stat, but its a new one, and my last one produced similiar results, it was changed early winter....
Is this sounding abnormal to you guys? My next step obviously is to take the stat out and test it but I wont have the time for a couple of days...I beleive its a stant, are non-cummins stats known for opening early?

 

I have heard some chit chat about some odd temp stats from various aftermarket companies that suppliers are selling. I say get one from the Big C and try it.

 

On a cummins engine, no matter the size of it, I'd use Genuine Cummins parts for anything that has to do with the engine itself. That's exactly what i do and would reccomend. I have a Cummins thermostat in mine and have never had a problem with it, rollin up on about 60K miles on it.