C12 coolant temperature high at 215 F

[Jerry Emert]

Highest temp between Moab and Grand Junction was 230.  Transmission checked by Allison shop yesterday.  Everything checks out good.  Hoses in good shape, radiator and CAC clear.  I found a hydraulic hose that had been worn down by the serpentine belt which they replaced, $ 195.00 for hose alone...ouch!  Changed Wic transmission filters out for Allison just in case.  Service manager says they have had a lot of problems with the type hydraulic fans in my coach and he suspects that is the issue.  Bottom line is when transmission temp goes up, down shift or slow down.   I will update after a long enough drive to see if the problem was the non allison filters in the transmission. 
Jerry

[Gerald Farris]

Jeremy,
The serpentine belt on your coach will not cause an overheating problem. The serpentine belt only runs the alternator and the dash A/C compressor. The water pump on a C 12 is driven from the timing case just like the hydraulic pump the drives the radiator cooling fan. So a bad serpentine belt will only overheat the driver when the dash A/C quits and the alternator stops charging.

Gerald

[Jeremy Parrett]

I learn something new every day.  Thanks Gerald.
  I guess I should have known that the water pump was driven internally.

[Lee Welbanks]

Jeremy,
When you are driving down the road can you hear your fan change speeds? I can hear mine go to a higher speed when the temp hits around 195 or so and slow back down around 190. Have you ever had your fan speed checked with a tach? A shop almost has to have a dyno to make the motor heat up fast enough, even with the radiator covered with a blanket.
If you were to pull over when the temp is showing 210+ set the rpm's up that fan should be screaming back there and you hear a big difference when the temps come down. I would almost bet your fan is not running at high speeds

[Jeremy Parrett]

Lee,
  with the windows closed and the a/c running I cant hear the fan on the C12.  I will try to stop and run back next time we hit 212 F and listen to it.
      You are probably right.......hope not !!
 

[Lee Welbanks]

You won't have to run it should stay at hi spd for awhile,  mine pulls so hard a shop towel will stick to the in side. Could be your wax valve is shot.