The old thermostat isn't maintaining the proper temps. It'll get up to 190, drop down to 160 (which is normal cycling), but then never gets hotter than 170 - 180.

I already have the thermostat and gaskets waiting on me at the Cummins dealer, but I don't know if there's anything I should know about before tearing into it this weekend.
Anything special to look out for? How much torque to retighten the housing bolts? Any exploded diagrams of this area of the engine?
I really need to order that service manual from Geno's!

 

Really a tuff job to change stats......mite need to go to the dealership.....they have the special high tech tools for this job....and the certified stat mechanics

 

Yeah right!
I'm guessing that was written tongue in cheek. So, it's that easy... nothin to worry about? What about the bolt torque? G'N'T good enough? (good'n'tight)
I timed the injection pump with no trouble, so I figure this oughtta go ok... I just wanted to know what I was getting into.

 

Jerremy:

It's a piece of cake. If you can do the timing you can do this. Get the gasket with your new thermo and might think about replacing the belt at the same time while you got her down. If you haven't done the KDP it's a good time to do this also while you are in there. PM Hauling in Dixie as he can give you some suggestions on thermostats and selecting the right one. Don't remember the post but he had some trouble with one of the thermos he got from Cummins. Don't hurt to ask the people with experience.

John (DH)

 

It's so tuff that I get my pet monkey (Samboo) to do it fot me!

 

Yeah, I seen HID's post. I ordered the one w/ the part # 3928499. I got this part # from the dodgeram.org site off a parts # chart for the 12 valve 2nd gens.

My belt still looks new, so I'm gonna ride that one out a whille.

Hmmm... I just found the TSb for the thermostat replacement on that site, too. Lotsa neat stuff on there.

 

The newest thermostat part number from cummins is 3934373 and is supposed to help with the fluctuation problem, but I have yet to try one, Goodluck,,Rick

 

yeah it is cake. the only work involved is removing the alternater first. i got the exploded diagram from the haynes manuel. i do not have any fluctuation anymore since i put in the updated cummins thermostat. i also changed all the old coolant at the same time.

 

I don't pull the alt off, I just remove the upper bracket and then drain about 1/4 of the coolant. If your coolant hasn't been changed for a while good idea to do it now.

 

Coolant is only 8 months old, and I recently added the prestone cooling system treatment to it. KDP is KIA. Cummins called today and said that my water in fuel sensor is in, too... I'll go get it all friday after work and get started!

 

Mine got stuck closed on my to a business meeting. (I was in a suit and tie) I keep a spare t-stat under the hood, 15 minutes later i was wheeling down the road to find a litle extra coolant to re-fill what i spilled.

Definately a technical job.