changing thermostat

[Cummins Cowboy]

I have noticed this summer my temp gauge is running up a lot higher than normal. I used to never be able to get the gauge to move past the first hash mark on the gauge now it goes to the third hash when pulling hills with the trailer, i used to see the gauge slowly rise to the first hash mark then it would quickly go just behind the first hash mark like the thermostat was opening up. So my best guess is that my thermostat is not opening properly. I just glanced at it tonight to see what it would take to change it. It appeared to me you have to take off the main belt and remove the alternator first is this correct??? also where is the best place to find a thermostat a regular auto parts store or cummins?? and also will i need a new gasket and RTV sealant.



Thanks in advance

 

[nascar mark]

Hi Cowboy,



Just have to remove belt and alt mounting/ pivot bolt and tilt up and away. Don't have to remove. Try Napa. Seal has a shoulder that needs to be installed towards the housing and torque to 18 ft/lbs.



mark

 

[rwinslow]

My $. 02 worth . . . . I replaced my original thermostat with a NAPA one that failed open in 4,000 miles. Went to the stealer and got the newest version - it does a much better job of regulating temp. in both winter and summer. In our neck of the woods I have had the best success with Hinckley Dodge for parts access and cost. You might also want to check your fan clutch and see if it is slipping. A Cummins mechanic told me that after 200,000 plus miles and 10 years that the fan clutches can begin to slip while in the actuated position. Finally, check your radiator for excessive bug or debris build-up.



The thermostat replacement is very simple and should take an hour at the most. Good luck.

 

[JTMcCracken]

I changed mine last week and I didn't have to remove the belt, just pulled the top bolt out of the alternator bracket and pivoted the alt. away from the engine, that gave me plenty of room. I used a cummins thermostat. Before the change the truck would slowly creep up to 220-225 degrees @ 72+ mph, now it's back to normal, 190-195 degrees. JTMcC.

 

[Bfulgham]

Cowboy:



This is a common complaint and has been on the TDR many times. Cummins has a new improved thermostat . I believe the part # is 3934373, someone correct if I'm wrong. It will come with an o-ring, I used no sealant. Get the CUMMINS.

Bob

 

[donald416]

Tstat part numbers

Hey there Cowboy,



I just installed a new thermostat 2 weeks ago. I bought mine from a Cummins shop. Cummins part # 3802968. Comes with Tstat, A flat type of gasket and a short piece of hose app. 26. 00 and some change.

PS I hvave 92 CTD LE ext Cab 153k



Donald

 

[CAROLINA CUMMINS]

Thermostat

Howdy





My guage usually reads between the first and second hash mark

and then, I guess when the thermostat opens it drops just below

the first mark. Is this normal ?? Might be time to change mine anyhow. 195,000 (91) Steve

 

[Cummins Cowboy]

Ok today i changed out the tstat Thanks for all the info guys. I used a napa one. It doesn't appear to be as well made as the orginal but oh well. They sold me this gasket maker material to make a new gasket. When i took it apart i didn't see how this stuff would work as well so i just used and cleaned up the old o ring gasket. At first the gauge was somewhat spastik it would go up about half way then the gauge would quickly drop just below the first hash mark. Later on it just mostly stayed just above the first mark. (why didn't they # our friggen gauges!!!!!!!!) I haven't had a chance to really romp on it and pull some hills will prolly get a chance to run it through tomorrow. I used to never be able to get it much above the first mark, heck i never heard my fan kick on until this summer i sure hope it works i like to run wide open alot and don't like to let off the throttle.

 

[19Kgvw]

There a two different thermostat part number talked about here.



# 3934373 and 3802968. I just ordered a thermostat from Cummins and didn't have my engine serial #. Now I don't know if I'll get the right part. I have a '93.

 

[Bfulgham]

19Kgvw:

Well here's another thermo. no. for you. I ordered a lift pump from cummins today and had them check the thermostat # for our 93's( used my engine no. ) He gave me 3802273 . I had got the #3934373 from someone at the TDR forum,but he said it didn't show that no. for our trucks. Someone said that was for an improved thermo. Go figure. I bet the one you ordered will work.

Bob

 

[19Kgvw]

Thanks for asking them Bob. So many part numbers and so little time... ... ...

The dealer wanted $48 for the thermo but cummins was at $25 for the thermo and the rubber seal. Napa's were $6 but it sounds like the quality leaves something to be desired.

Thanks again.

Rich

 

[Bfulgham]

Rich:

Let me know what Part No. you get from cummins.

thanks : Bob