goatmarty

I was wondering when driving normal without pulling anything my tempature wiill rise to a little over half way then it will drop back down. I wondered if it was the water pump,radiator, or what.

John_P

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goatmarty:

If you are referring to the coolant temperature gauge, the cause of that is usually a worn out coolant temperature sending unit. I have had to put two of them in my 1996 and it takes care of the problem.

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John_P

dozer12216

or the normal cycling of the thermostat. A new one from Cummins or Dodge is generally in order if cycles wildly or out of range.

Dartmouth 12V

The reason for the cycling is that your thermostat closes and the engine temp will increase as indicated by the gauge. At the same time, the coolant in the radiator is cooling off. Once the thermostat is opened, the colder coolant will make your temp gauge drop quickly and the thermostat will close again allowing the cycle to repeat.

This is totally normal and present on all trucks. Some people have had good luck with an updated thermostat from cummins but that seems to be hit or miss. There are two ways to make it stop. One is to block the radiator when it is cold out so that the coolant in there doesn't cool down as fast, this is a good thing to do. The other is to hook a big enough load to the truck that the thermostat is open almost all the time which is obviously not the best solution in all cases.

The only reason to be worried would be if the cycling you are seeing is going above 200F or so. Otherwise try blocking your radiator a bit but don't worry too much.

infidel

Totally normal although some folks strive to fix a problem that doesn't exist.
Cummins got tried of people whining about the temperature swings and moved the temp sensor to a different location on the block in 1998.
The temp still swings on their engines too, they just can't see it.

John_P

You guys have all brought up good points on the engine coolant thermostats.
Thanks for giving input to this Member.

One thing I wanted to add is the sending units are located in the cylinder head around the back of the engine, but more towards the driver side, at least on my 96'. I have also seen problems with the electrical connector which goes to the sending unit getting brittle and worn and that also can be an issue. It is pretty hot back in that area and over time those connectors just wear out.

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John_P

lgp9999

I see mine swing. It just doesn't swing much. It goes back and forth between 170ish and 185ish