Engine/Transmission (1998.5 - 2002) Water Temp Problem

[JHarrington]

All,

I've got some sort of problem with my water pump or thermostat. While unloaded driving down the road at 75mph my water temp constantly bounces back and forth from 190 - 215 degrees all day long. Not unbelieveable fast, but just keeps constantly moving back and forth. I've checked my antifreeze, I've got a thermostat that's only 6 months old and just a year ago I completely removed my radiator, CAC and condensor and thorughly washed them all out. The radiator I even had boiled. Please advise what anyone has seen, I'm some what suspect of the water pump now that it is the only component I haven't replaced or opened up yet. Thanks, JCH.

 

[JFaughn]

What brand of thermostat is it ?
What is happening is that thats right at the opening closing temps , its not really a problem , unless its just irritating , if you go for a replacement , go to a Cummins dealer , more often than not you get a much better quality part .

 

[CumminsPower98]

You can rule out the water pump. Generally the only problems water pumps have is to leak and or the bearings fail. I suppose the impeller could fall off or rust so bad it becomes ineffective but these are both very unlikely and wouldn't cause your temp fluctuation.

 

[B.G. Smith]

Thermostat. bg

 

[OL RATLR]

Thermostat. bg

Could be the sensor.