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OurNextRVAdv · 09-06-2021, 08:47 AM

In May, we overheated several times pulling over the Continental Divide in Colorado. Got to our destination in Breckenridge for the summer and changed both temp regulators. Our slobber tube was fixed four years ago. I made sure our coolant was full, cleaned both sides of our rear radiator with Extreme Simple Green Aircraft cleaner and hoped for the best.

Left September 3rd and noticed our coach was running between 195-199 cruising through flat eastern Colorado/western Kansas on a 85 degree day, sometimes heading upwards of 203-205. We consistently ran 185-189 beforehand. Any suggestions on what to check next?

Also, for those who have cut a hole in the shroud, can I get a picture of how it turned out and what you used to secure it.

Smitty77 · 09-06-2021, 02:22 PM

Are radiator hoses OEM? Possible under high flow situations, for the return/intake hose to the radiator to collapse. (Can't always tell by the 'squeeze' test.)

Thermostat's not opening up all the way, can also match your problem.

C7 era? (Guessing from the 350HP size.) Are used in many, many coaches of that era - so hoping someone with more hands on experience then I have with CAT will say 'Oh, that sounds like....'!.

Best of luck,
Smitty

bneiva · 09-06-2021, 02:30 PM

After overheating..... my "guess" would be your thermostat. At least that is the least expensive item to replace.

Bill
03Tradition

wolfe10 · 09-06-2021, 02:37 PM

If rear radiator/CAC, clean the front of the CAC.

This is annual preventive maintenance with a rear radiator DP.

OurNextRVAdv · 09-06-2021, 02:37 PM

Quote:

Originally Posted by bneiva

After overheating..... my "guess" would be your thermostat. At least that is the least expensive item to replace.

Bill
03Tradition

Replaced both temp regulators in May.

Smitty77 · 09-06-2021, 03:16 PM

Quote:

Originally Posted by OurNextRVAdv

Replaced both temp regulators in May.

Assume the 'temp regulators' is the Thermostat(?). (And did not know C7's had two of them(?), so thats a learning curve for me

!). IF, what you replaced were Temp Sensors, it is different then the Thermostat. (And we all use different vocabulary. My intent on asking is only to clarify

!).

And replacing the Thermostat, would not stop the return hose from collapsing under high cooling demands.

And not unheard of for a new Thermostat, to be bad(:!

Again, best of luck on this. Will follow the thread for my own info learning,
Smitty

OurNextRVAdv · 09-06-2021, 10:04 PM

Thanks Smitty!! I should have mentioned we have a C7 350hp. These engines have two temp (thermostat

) regulators needing replaced every three or so years. My next step is to check the water pump belt/tensioner and for leaks at the water pump.

Skip426 · 09-06-2021, 10:18 PM

Why Caterpillar chose to call coolant thermostats " temperature regulators " is anybody's guess . My theory on the use of two , is that the opening in one wouldn't pass enough coolant under heavy load and a large single thermostat would require a redesign of the head.

Anyhow , after multiple overheating situations ; accuracy of the coolant temperature sensor could be in question .

CountryB · 09-07-2021, 05:26 AM

Quote:

Originally Posted by OurNextRVAdv

Left September 3rd and noticed our coach was running between 195-199 cruising through flat eastern Colorado/western Kansas on a 85 degree day, sometimes heading upwards of 203-205. We consistently ran 185-189 beforehand. Any suggestions on what to check next?

What do you consider overheating? 203- 205 is fine. It's when you get to 225 that you need to be concerned.

I understand that you saying (above) it's running a little hotter than it usually does. Are you relyign on the dash gauges for your temp readings (or do you have an Aladdin or ScanGuage D or similar to read from the engine ECM data?

The engine temp is relative to ambient air temp and engine load. Mountain driving puts a lot of load on the engine.

Are you approaching 225 degrees? What temp did you hit when you overheated in Colorado?

OurNextRVAdv · 09-07-2021, 07:35 AM

Quote:

Originally Posted by CountryB

What do you consider overheating? 203- 205 is fine. It's when you get to 225 that you need to be concerned.

I understand that you saying (above) it's running a little hotter than it usually does. Are you relyign on the dash gauges for your temp readings (or do you have an Aladdin or ScanGuage D or similar to read from the engine ECM data?

The engine temp is relative to ambient air temp and engine load. Mountain driving puts a lot of load on the engine.

Are you approaching 225 degrees? What temp did you hit when you overheated in Colorado?

On my coach, overheating is at 225 degrees. I consider running hotter when my normal running temps for the past three years on flat lands (eastern Colorado and western Kansas) have been 185-189 and now I am seeing normal being 199-203 after the new temp regulators were installed. I do not have a scan gauge and I am relying on the dash gauges and the driver information center.

I may have gotten a bad temp regulator and might replace them again to see if it makes a difference.

Jubilee 45 · 09-07-2021, 07:58 AM

We have the C13. New t-stats, new CAT ELC. When warmed up, running down the road we are 202-204 degrees.

KanzKran · 09-07-2021, 08:06 AM

Quote:

Originally Posted by OurNextRVAdv

I consider running hotter when my normal running temps for the past three years on flat lands (eastern Colorado and western Kansas) have been 185-189 and now I am seeing normal being 199-203 after the new temp regulators were installed. I do not have a scan gauge and I am relying on the dash gauges and the driver information center.

I may have gotten a bad temp regulator and might replace them again to see if it makes a difference.

Not trying to be snarky, but how do you know that the 185-189 temp range was actually the right range for that engine? Given the age of the coach, it would seem likely the thermostats had been changed at least once in the past, before you got it. Unless you're the original owner.

I'd ask Caterpillar what it should be, based on the actual engine S/N.

OurNextRVAdv · 09-07-2021, 10:32 AM

Quote:

Originally Posted by KanzKran

Not trying to be snarky, but how do you know that the 185-189 temp range was actually the right range for that engine? Given the age of the coach, it would seem likely the thermostats had been changed at least once in the past, before you got it. Unless you're the original owner.

I'd ask Caterpillar what it should be, based on the actual engine S/N.

Thanks for the suggestion. Called CAT this morning and it seems my engine most likely had the old temp regulators, part #119-3075 that opened at 201F. CAT has upgraded the regulators to part #115-4223 which now open at 206F. For maximum efficiency, CAT said the C7 should be running around 200F, which is why they upgraded the regulators. So, it looks like I put too much thought into it and everything is now the "new normal:-)"

Thanks for everyones input!!!

Skip426 · 09-07-2021, 10:50 AM

Quote:

Originally Posted by OurNextRVAdv

Thanks for the suggestion. Called CAT this morning and it seems my engine most likely had the old temp regulators, part #119-3075 that opened at 201F. CAT has upgraded the regulators to part #115-4223 which now open at 206F. For maximum efficiency, CAT said the C7 should be running around 200F, which is why they upgraded the regulators. So, it looks like I put too much thought into it and everything is now the "new normal:-)"

Thanks for every one's input!!!

Thanks for wrapping up your post with the detailed info ; part numbers and operating temps ; I'll keep the numbers in mind when I next change my temperature regulators .