Greetings! Brand new here and I thought I would try out a question for some help. I have been experiencing, for a while now, water temp fluctuations. I have a 1996 Dodge with the 6 cylinder Cummings. I bought the truck new and it doesn't have any real modifications from factory. While driving, I am getting readings from 150 deg to 180 deg in about 2 minuets. I can go for 50 miles and it will be steady. Then, for no reason it moves up or down. I have had installed a new water pump, thermostat, fan clutch, sending unit, and two complete system flushes. What in the world is going on? Any advice is greatly appreciated.

 

Its a Cummins not Cummings

Luke

 

Yup Cummins and the guage moving is just your thermostat opening and closing.

 

Would you belive auto correct misspelled Cummins. That's my story and I'm sticking to it.

 

Must not have the updated cummins t-stat. The gauge cycles much less with it. It drives me nuts watching it.

Here is the cummins part number you need.

3934373

 

It bugs the heck out of me whe people say Cummings..

but I do have to agree my auto-correct tries to chage cummins to cummings

either way, a quality cummins t-stat should help

 

Same stuff happens to me, I think its just the auto parts store thermostats. I need to get a Cummins one in there.

 

The updated cummins one still cycles the gauge, just not as much. The reason it cycles is because the rad is HUGE and when the stat opens, the rush of new cold coolant slams the stat shut. This will continue till all the coolant in the rad has got to operating temp.

So 3 hours of driving later, the gauge stays put.

 

The way I see it A giood cooling system is a beautiful thing, I can watch the guage fluctuate all day.

 

Completely normal. As others have said, it's just the thermostat opening and closing.

In 1998 (IIRC) they changed that because people were concerned. If you ride in a newer one, you'll notice it doesn't fluctuate like that -- not because the temperature doesn't really fluctuate, but because it kind of dumbs it down -- takes an average if you will.

Basically, if it DOES NOT fluctuate, you might have an issue, otherwise you're fine.