I don't know if it's because it's not working, if it's the sender that's not working, or if I'm simply not getting over 140*? I also have no heat. I searched around and I was reading a couple threads on here about putting cardboard in front of the radiatior etc. I should still register on the temp gauge though no? It used to work excellent, up to 190°, drop down to 140°, back up to 190° and just cycle like that...

Thanks,
Dave

 

Becouse of no heat I would say that you may have a stuck thermostat , get one from cummins and you may not see the cycling any more, if it was a sensor , guage problum , use a muti meter and check for resistance , it should not be open , the exact res. is in the manual , or maybe someone will post it.

 

I thought that cycling was what it was supposed to do as the tstat opened and closed though, when it was warmer out?

 

I had the same problem, no heat in the cab or gauge. The thermostat was the culprit, as it was stuck open. I always put a new one on a pan of water with a thermometer to make sure it works properly, before I put it in the vehicle. I had a new one not open at all, and almost fried the engine. A easy test is to take the old stat out and put it in a pan of water.
I don't think the "cycling" is normal. I have never had any car or truck in my life "cycle" up and down. The stat should open only as much as needed, not in a "all or nothing" mode.

 

The cycling is definately normal, the rads on these things is so big it drops the temp big time which closes the tstat until the heat builds up again.The only time mine doesn't cycle is in the summer with the a/c on and towing heavy then the tstat stays open as there is enough heat to keep it oepn.
If you ahve no heat then i would suspect your tstat is stuck open, there is a rubber gasket/sleeve that will distort and actually get caught in the tstat and hold it open. Go to cummins and get a new tstat and rubber.

 

From what I've read it seems that the after market [ none cummins ] T-stats. have more problums, shorter life and cycle . I am the 2nd owner on mine and have not replaced it yet . and it stays steady at 180 , winter, summer,towing.

 

That is exactly what happened to mine, the rubber distorted and held the tstat open. It now runs at 180, no matter what I do to the load, or no matter how hot it is outside. Never cycles up and down.

 

Yeah I have an AutoZone tstat in there. Appreciate all the help. I will see if I can find a local Cummins place and pick up a new tstat and see if that solves the problem. I still think it's crazy the lift hook is AROUND the tstat neck thing!