Engine/Transmission (1994 - 1998) temp jump

[grincon]

On a 1995 12 -valve: the temperature gauge jumps above 190 degrees; at times it could be 210 or even higher and then comes back down. At times up and down. 220,000 miles. Any possible solution? Thermostat perhaps?

Is it unique to 12 valve trucks only?

 

[HoleshotHolset]

My '94 started doing that about a year ago... it would bounce between 190°F and about 150°F. At first I thought it was the sensor or the associated wiring...



So, just after Christmas - I swapped in a t-stat from the local parts house. What a waste of time that was. Now the temperature swing went from 150°F all the way up to 210°F or so!!!! ARRRGH!



A day later I found a box in my room with a brandy-new t-stat and jiggle valve hose in it - all OEM Cummins parts. :-{} I swapped in the Cummins t-stat and the gauge held steady once it was up to temperature. That's the only variable I changed... so it had to be the t-stat.



Don't buy anything but a genuine OEM Cummins t-stat... local parts store t-stats will fit in the housing and it won't leak... but it will cycle to NASTY temperatures and then back down.



Matt

 

[McCRam]

The 12 valves typically have a swinging temp gauge. It seems to be normal. Mine will swing between 150 - 190 all day long. Although if it just started you might want to check into it.



It didn't take me long to realize that stores like napa and checker cummins parts are junk. Every time I did get a part from them, I ended up taking it back . oem cummins only for me.

 

[dodge cummins]

i know on that era of 12 valves the thermostat did vary alot sometimes going well above 200. cummins came out with the new thermostat to correct that problem. i no of a guy who had a 97 who lost the engine do to the factory original t-stat. make sure you get the cummins oem t-stat,its a 180 degree t-stat. ever since i changed my t-stat my temp gauge is not all over the place anymore.