I've noticed a problem with the fan that seems to be getting worse. When I'm hauling, the fan won't come on when i'm on the throttle. The temp gauge will go almost to the end of the white, then come back down when I let off. The fan will come on when i'm not on the throttle and the temp gets over 190. It used to come on any time the temp got over 190. I suppose that means the fan clutch is going out, but I wanted a second opinion before taking it in. It's on the work truck, 2002 HO 6 speed.

 

My fan's been on the shelf for so long that I can't remember how it behaved.

Sounds like the clutch is going, though.

Justin

 

You have your fan off in the summer too?

 

When I'm towing, my fan clutch works more after I've stopped than it does when I'm towing. It seems like almost every stop light I leave from has the fan hooked up. My thermostat is slow to open and generally goes up like yours untill it opens and settles back down to just above 190 when towing.

I'm going to install a 180 thermostat when I change the antifreeze out in December. In my opinion the 190 thermostat does not leave any room for temp increase when towing. It would be good to have the extra 15 degrees before the howling fan gets off.

Dave

 

Where can I find a 180* thermostat? Part number? The local NAPA only carries 190's - or so they say. Also, does installing a 180 thermo require any re-flash or re-programming or is it simply a bolt-on and go? I had a 96 Chev and I installed a 160 thermo and reprogrammed it for such. The fan wouldn't hardly ever disengage and my mileage went straight to hell - especially when towing.

 

I have not called Cummins in Orlando yet to find out about the 180 and if it changes anything. It could, I guess with the computer but I would not think so. Will let you know.

Latter; Called cummins, off course they only stock the 190 part number 3935825. That may or may not be for your engine.
Gonna check around on TDR and see who has used on and were they got it.

Will get back to you.

Later again; 180 thermostat part number 3967195 30bucks maybe. Cummins has so many part numbers for engines, its a wonder they can find anything.

Dave

 

i would not change to a 180, ive been there and done that, you are trying to hide a problem by going to the lower thermostat,if you live in the desert maybe but not normal running conditions, the dodge trucks have a problem with the radiator getting clogged on the out side and not letting the air go thru the radiator to cool it,easy and cheap fix is to just take some time and pull it out and preasure wash the radiator to make sure it is clean,same thing for the clutch fan they get caked up with the oil and road grime they need to be cleaned also,i believe you are having a clutch fan failure but do these steps to make it better, i have done this persoally and my temps went from 220 plus to cruzing with a 3 car trailer loaded in the summer at 210 max on a hill,just a lil helpful info good luck

 

Well, in general you may be right about the radiator. Not in my case. The thermostat in my vehicle opens slow and has a tendancy to stay on the warm side. The raditor is clean. Every diesel vehicle I've owned in the past 20 years starting with 5.7 gm screw up have all run 180 thermostats. They all came with 190 or 195's. The 6.2 and 7.3 I had both ran on the 190 plus. The 7.3 would run up in temp like the dodge does now when towing. I put a 180 in that and it solved the problem. You got to remember most of my towing is south of I-10 for the most part. Its not the desert, but road temps can be in the 140's at times.

I did make the big square some time ago from hear to Galveston, Tx, to Duluth MN, to Harvard Mass and back to Melbourne, Fl only having a little fan noise in the mountains.

That 190 we have is there for fuel burn and emmisions more than anything. Heat is also wear. Up until the electronic engines came out for marine use, 180 was the temp of choice. Now to make HP and the terre 4 emmisions the temps are up just like our engines.

I really don't think a 180 would be bad in a cummins engine. Its not want Cummins wants or the feds but its want I would like to do for my application. If it gives me less mileage or any adverse
effects, I'll change it out.

Dave