Thermostst

[ragjoint]

Changed coolant about a month ago and today the temp gauge would not go above the first line above 140. Anybody have the part number for the improved thermo from Cummins? Also installed the stage 3 [1 ton] disconnect eliminator kit at the beginning of July, will give a 4 month oppinion [sic] at the end of this month. Thanks

 

[PUMPERDUDE]

Could be jammed.

Mine was . Figured I better change it before the cold gets here. It had been running pretty cool all summer. When I finally got arround to doing it,a piece of metal had it jammed. Looked like a piece of casting that was punched out with a little twist to it. You think it would have came out of there before 162000 miles.

 

[HEMI®Dart]

Cummins p/n 3934373 is the newest 12V T-Stat.

 

[ragjoint]

t-stat

thanks pumperdude and hemidart- just got back from Cummins, had not seen your posts yet. They sold me a t-stat with p/n 3802968, doesn't seem like the most recent to me, so I'll take it back tomorrow and exchange it for the correct p/n- glad you guys are out there watching over us youngsters! It looks like it'll be an easy job, just remove the hose and move the alt and that's it.

Thanks again! DA Emmitt

 

[SlyBones]

3934373 is the latest part number. 3928499 is the part number off of Fritz's page, typically a good source of information.



Next is do you have any symptioms with the commonly reported gauge fluctuation? I ask because this is a fairly common complaint, even though normal and nothing to worry about. Many have swapped the thermostat to correct this. The latest one is supposed to fix the fluctuation. I have seem post stating that each of the above is the one to get. That each one is the proper one to fix the fluctuation.



My experience. I got both. I ordered the 3934373 part from Geno's. Then read one of the above metioned posts. So I went to Cummins and got the 392499 part and had both on hand when I did the job. -- My truck did have the fluctuation behavior. -- When I took out the thermostat, the old one was the 3928499 part. So I went with 3934373 when I put it back together.



The fluctuation is gone. It now holds steady. A little lower temp than I expected, but within range on the gauge. However I have noticed that it warms up much slower that with the other TStat. So while fixing the one behavior, I now have a different one.



Anyways I just thought I would share this, since the question was related to getting a new TStat based on slow/no warmup. My experience is the new TStat made warmup worse not better. What got better was the fluctuation.

 

[400Magnum]

TEMPERATURE RATINGS

Just wondering, are the t-stats for our Cummins available in different heat ranges like the gassers? You know, some are rated to open at 165 degrees, some at 180, others at 190, etc. I'd like to swap mine to end the fluctuation, but I don't want to end up at a lower temperature than what I have, if anything, I want to go higher. If the gauge on the dash is relatively accurate, my engine never gets above about 170-180 degrees. I usually drive pretty easy, unloaded, not towing. But even when I go down the interstate at about 80 mph, I never get to 190 degrees.



If so, any idea what part numbers correspond to the different temperatures?



I'd like to get it to run a little warmer if possible, just because I was told it would possibly help increase fuel mileage if the engine ran warmer. Any truth to this?



Thanks in advance!

 

[jolyman]

Thermostat Problems

Happy 2002 to everyone. .



I just made a trip to Tucson and back pulling a 19' TT trailer back. I'm not impressed with the MPG back (10) but better than the gassers.

BUT to the subject at hand On the way home in a snow storm on Raton Pass I lost the thermostat and ran COLD all the way home in the middle of the night -- GLAD I had winter guards on.

I need to know where the thermostat is located (under the housing that serves as the alternator bracket???) or somewhere else? I have had the fluxuating guage problem also and the old therm. never got over the 185 or 190 mark then back down to 140 to make the trip to 190 again -- just figured it was normal so I left it alone.

What is the latest PN:# I don't mind the flux. but DO want fastest warm-up I can get in the winter here in Colorado.



Thanks for the help in advance to All.

 

[illflem]

I had the same problem as Slybones after replacing with the "improved" tstat. I finally went to Napa and asked for a 190° stat to fit, price was less than $10, sorry I no longer have the p/n. That was three years ago it's been working great but I still have to use a winter front and run fanless in the very cold weather to get the temp up.

 

[sewman]

I put a stat in from thr Dodge 360 engine a couple of years ago heck,you can get em anywhere.

Bob