Does anyone know if there are different thermostats for these engines? I have a 98 12V and have replaced the bad original due to not warming issues. Napa brand, would only get to half way from low normal line to 190 mark. Changed to the Cummins number found somewhere on this board, essentially the same result. I remember my old 97 running nicely to 190 and then nosediving to low normal and cycling thereafter. Is it likely that the temp sensor is bad? The truck only has 84K on it and runs like a top.
Thanks
Quinn

 

Cycling of the thermo is pretty typical. There is a later thermo from Cummins that isnt supposed to cycle but it takes long to warm up. my 95 goes from 190 down to 140 or so all day long.

 

If you're using the stock gauge, you probably don't really know what's going on. If it's accurate, that's probably more by chance than anything. Nothing against dodge stock gauges, I've just never heard of a stock temp or oil pressure gauge being accurate.

 

If you search around here or on dodgeram.org, you'll find the part# for the one that warms up fast and cycles. Mine came w/ the new one, so I switched it out. Got tired of freezing my butt off for 10 miles in the winter.
Here... I even found the link!
http://dodgeram.info/tsb/1994/07-07-94.htm

 

moonpie,
i just changed my tstat to the cummins 180 #3967195 a couple of days ago, and when i was at cummins the guy printed me a sheet explaining the cycling problem with the stock tstat #3928499 for our trucks. on that sheet it had a revised tstat #3934373 stating this tstat was the cure for the cycling problems in these trucks. have a good one Marks2500

 

I tried the new improved stat and while it stopped the cycling it made the engine run much cooler, heater didn't cut it in the Montana winter.
I went back to the old stat.
Might be ok for folks who live where it doesn't get cold but not for me.