96 3500. Temp gauge sweeps back and forth. goes from 140 to about 200 then back. Over and over..slowly.

Bad sending unit?

Thanks!

Dave

 

My truck does the same thing.
I have read that this is normal, due to the big raditiors these trucks have.
when i work my truck(pulling a trailer @80 mph) the temp stays right at 210. it hasent posed a problem for me yet.

 

Totally normal.
Cummins changed the location of the temp sender in '98 so people would stop complaining.

 

i like watchin it fluxuate in my 95, you know when its gettin hot or when its cooled down to shut the motor off (im all stock on this one so no aftermarket gauges)

 

This terrifies almost all new owners and if you use the search feature, you will find many posts about it. However, it is totally normal and nothing to worry about. It is just the thermostat opening and closing and the fact that these trucks have huge cooling systems.

 

Wow! Weird that it is normal.

Thanks!!

Dave

 

If you ever hook up a heavy load like the cooling system is over designed for you'll be glad that it fluctuates when empty.
With a load the gauge will sit still.