The engine temp on my rig is fluctuating between 190* and probably 215*. The coolant is full and the radiator is clean. I replaced the thermostat and fan clutch last June, now the only other thing I can think of is a bad sending unit. Can anyone tell me what I need to do or replace to get it running back where it should? Thanks

 

Most likely you need a thermostat.

Also, if you have any leaks at all, you can gt this condition. Or a weak radiator cap will also cause this.

Dave

 

If the radiator cap is weak would there be some leaks around it or how can i tell? I don't think I have any leaks in the hose because I'm not losing coolant. Since thermostats are cheap I'll give that a try. I appreciate your help. Thanks

Seth

 

Usually a bad cap will have no outward effects. Meaning, they don't leak. They just don't hold enough pressure typically.

A rad shop can check a cap in about 2 minutes and let you know if it's bad.

Dave

 

Do yourself a favor and get the stat from Cummins. Dont rely on a parts store for this item.

 

I called Cummins Southern Plains and got a stat from them. Thanks for the help guys

 

I hyave had 3 bad T-stats from Cummins NW before buying a Mopar T-stat. They are clearly different, so I do not know if it is a rebadged part of not.

So far, Only the factory units seem to be holding up for me.

Dave

 

Bad Cap...

Bad T-stat - I replace my t-stat every time I cahange coolant which happen to be every spring. So I normally don't see coolant system problems...

Or you got air trapped up in the coolant system yet... I typically se wild temp swings for about 1-2 days till all the air comes out of the coolant system. Usually see a fall in the level of the coolant in the bottle for about 2-3 days and quits...

 

How does the radiator look around the fan shroud? I'd make sure it's not caked with oil from the oil/pill bottle that sits on the front of the block. They get full, oil starts running out and sucked into the fan and it cakes/coates the radiator core.

 

in the fall I cleaned out the radiator core with carb and choke cleaner and blew out all the guts and caked oil. towards the bottom of the block on the drivers side the little tube for oil blow by is a little short but there is no bottle at the end of it. Should I put an extension on the tube so oil doesn't blow all on the block? I did notice the fan blades are a little caked too. The temp swings first happened when I had about a 5k pound load on going to east Texas. When I left it was normal but on the way back I noticed the higher temps. It doesn't boil over and my mileage hasn't changed so I don't think its running hot enough to hurt anything but I don't like it running hotter than it should.