wannadiesel

Your temp gauge, that is. I replaced my old thermostat with the newest, latest and greatest, super improved genuine certified true blue Cummins thermostat and the temp gauge still swings back and forth all the time. Anybody know the secret to making one of these run at a stable temperature?

ihpower

i got a new carquest thermostat and it still swings.

bgilbert

Dave, I replaced mine with a Cummins 180* stat part number 3802968. Did the search and it was supposed to be the updated non-fluctuating t-stat. I have a mechanical temp gauge plumbed right at the t-stat, it does NOT swing/fluctuate.
Edit: Dave what part number did you get and where?
BTW, anything less than Cummins parts, is.

wannadiesel

Bill- I got 3802968 from Cummins Power Systems out of Harrisburg, PA.

It's not the gauge. Running on the highway I have to chase the thermostat with the temp slider on the heater. Running with the winter front closed off straightens it out, but the EGT's go up really quick if I start playing around.

swank

i had to vote for a swingin old/unknown. but it's a new napa cuz cummins is so far away.

sammy340

My Gauge swings up and down like crazy as well. Mine is the old/unknown swinger.......


I'd sure like to get mine stable as well but it looks like the new cummins ones don't do the trick

92DIESEL

Mine goes to the first middle hash mark, then backs down to just above the left hash mark once the Tstat opens. Once it opens the first time it is very stable just below the first middle hash mark. Unless I am hauling hard up a long grade, them it goes up to about middle. Very stable though.

Good luck Dave,
Michael

PS we could just trade trucks if you want

swank

nothin worse than an old/unknown swinger, eh?

banzaitoyota

My swinging stopped after I flushed my radiator and replaced the fan clutch and fan

G1625S

yeah, but they can be the most fun...errr, so I've heard, anyway

Dave: It surprises me somewhat that your heater control has any effect whatsoever on coolant temps, being the heater core holds such a small amount of coolant when compared to the block and radiator...

Mine behaves thusly, FWIW:
Needle slowly swings to first mark past middle before t-stat opens for the first time of the day,then settles to below normal temp (two lines below middle) and gradually rises to normal (1 line below middle). If I run 60 or less, it'll run cool. Over 60 it'll run fairly normal. In town, or on a long downhill, the t-stat will close, she'll heat back to one line above middle and when the t-stat opens back up, the whole process repeats again. Being that I have the poor-boy package, I don't have a valve in the heater hose---just a trap door in the HVAC box...FWIW.

BC847

Mine's a swinger, . . . . . . . but only in cool weather.

Monty

No swinging here. Updated Cummins T-Stat for 2 years.

funcruise

think you boys are worrying too much about a non problem. I have driven many cummins engined diesel highway rigs for the last thirty sum years or so and Id say ninety percent of them,the temp gauge would roam up and down. Seems to be just the way their cooling system is, although come to think about it they also had rad shutters too. Anyway just a thought........

BC847

I wonder how many folks came in this thread thinking it was about, . . . .. . . . never mind.

timb

Dave, you are a bad man.But after reading your post, I will tell you that the thermostat in myn truck does not fluctuate at all. and it is the original. maybe that's the secret.