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Winepress · 06-11-2015, 02:34 PM

I had the bad luck of a broken serpentine belt on my Cummins ISC motor. My warning light came on and we immediately pulled over and stopped the engine. Had it towed to the nearest Cummins dealer where they replaced the belt and added about a 1/2 gallon of coolant. The coolant escaped out of the overflow tube as the engine got hot. I know this because it coated my toad.
Everything is now running fine, plenty of power, turbo pressure good, except I am now running about 10 to 15 degrees hotter than I usually run. Fan seems to be kicking in more often. No difference on hills, it runs the same temp, just cruising on a flat road it is running hotter. I got underneath the coach (rear radiator) to see if there was anything affecting the airflow and everything looks fine. It's been a few days now so the engine has gone from hot to cold so I don't think I have any air in the cooling system.
The only thing I can come up with is the thermostat. Maybe when it got hot something happened to it. I usually run at about 180 to 200F, now is 195 to 210.
Has anyone had a similar experience? Any ideas as to what to check?
Thanks

JRPA · 06-11-2015, 03:08 PM

I think your on the right track with the thermostats. you probably had a 180 degree thermostat and they may have changed it out for 190 degree thermostat.

ecurb74 · 06-11-2015, 03:34 PM

Doesn't make sense to me. Why would they change out a thermostat just to change a belt? I take the belt is tight and not slipping? Also recheck the coolant level, did they just add water to the reservoir and not the radiator? Did they change the thermostat? If so it would be on the bill.

DMTTRANSPORT · 06-11-2015, 03:37 PM

Air Bubble in the coolant, not full? How Hot did it get??

Kpjp · 06-11-2015, 04:37 PM

Sounds like the radiator may have been coated. Spray Simple Green on both sides of radiator, leave on for about five minutes and then wash it off with a garden hose.

Good luck,
Jim

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Winepress · 06-11-2015, 05:36 PM

Thanks for your replies.
The thermostat was not changed, just the belt and added coolant. I've gone through several cycles of driving and cool down at night, so I do not think there could be any air in the system.
I will re-inspect the radiator to see if it is in some way gunked up, however, if it were, I would think it would get hotter on the hills. My climbing temperature is remaining the same.
Today, same results. Warm up time was the same, driving temps higher.

DD788Snipe · 06-12-2015, 06:21 PM

If your engine did over heat it could have affected the thermostat in that it's not completely opening. If it's old I would change it out. It might come back to haunt you on the road.