Cummins ISB 6.7L CM2150 temp goes to 207f. OK?

[Kahoona]

We were driving in rolling countryside in Northern FL. We were running at 75mph on cruise control with outdoor temps at 8ff and towing a Tracker. The temp is usually around 185 or less and it crept up to 207f. When we reduced speed of stopped in a rest stop it went straight to normal right away.

We have 26,000 mi on it. I have never had a healthy vehicle that did not remain at the center of the temp gauge no matter what. Should I be concerned?

[Finance]

It’s normal for my 360 ISB. But if yours has just started this at 26k after consistently running cooler I’d say you are due for a radiator cleaning.

[RichKimball]

I don't think it's normal especially for your year engine.
To me...it sounds like the beginning of the fan clutch failure myself and so many others have been unfortunate to have.

There are several lengthy threads about this....but the bottom line is that the Horton fan clutch develops this problem and the fix is replacement.

I was lucky to be able to replace mine DIY @$700 but others have incurred much higher price tags.

Sorry. Of course....not to forget about a good cleaning of the CAC and radiator. Maybe that's all you need...hope so.

[Kahoona]

The engine speed has not given us any more trouble however the weather has been cold so that may have had something to do with it. Thia might be odd but the "resting temp" has risen to 194 and it never rises above that. I will clean the radiators next time we stay somewhere with water and do some research to see how to test that fan clutch. We should hit the Texas hill country sometime within the next week and that may show us wether we have a problem. I'll let you know.

[RichKimball]

Pulling the fan fuse is the only way to test for failure of the clutch or so I've been told and read.
In my case, it didn't help as the clutch was already gone and slipping badly.

The way the coolant temp is supposed to work (accordingly to Cummins and Freightliner) is that a 190 degF thermostat should be installed. (which I did as an upgrade..there was a bulletin about doing that).
The coolant should go from 190 to around 205 (which is when the fan is supposed to kick in full speed) and then drop back to 190.

Good luck.

[Kahoona]

Originally Posted by mevman

Pulling the fan fuse is the only way to test for failure of the clutch or so I've been told and read.
In my case, it didn't help as the clutch was already gone and slipping badly.

The way the coolant temp is supposed to work (accordingly to Cummins and Freightliner) is that a 190 degF thermostat should be installed. (which I did as an upgrade..there was a bulletin about doing that).
The coolant should go from 190 to around 205 (which is when the fan is supposed to kick in full speed) and then drop back to 190.

Good luck.

Interesting. I am guessing that pulling the fan fuse lets the temp rise so I would know that the fan was working when it was in. We see what happens when I hit a hill or two and I can try that if there is a problem.

[RichKimball]

Originally Posted by Kahoona

Interesting. I am guessing that pulling the fan fuse lets the temp rise so I would know that the fan was working when it was in. We see what happens when I hit a hill or two and I can try that if there is a problem.

Pulling the fuse allows the clutch to lock up....letting it run full speed.

[ualdriver]

Originally Posted by Kahoona

We were driving in rolling countryside in Northern FL. We were running at 75mph on cruise control with outdoor temps at 8ff and towing a Tracker. The temp is usually around 185 or less and it crept up to 207f. When we reduced speed of stopped in a rest stop it went straight to normal right away.

We have 26,000 mi on it. I have never had a healthy vehicle that did not remain at the center of the temp gauge no matter what. Should I be concerned?

I have a 2013 Fleetwood Excursion with a ISB 6.7L engine.

I started a thread last summer and received good advice that matched what my mechanic and Freightliner told me. I was driving on a flat road at 65mph. The coolant temperature would slowly rise to the low 200s, the fan would come on (I could hear it), the temp would drop down, the fan would shut off, then the process would repeat. I was told that was normal ops. That seemed weird to me as it wasn’t particularly hot out and the engine wasn’t under a heavy load at 65mph I don’t think.

Anyway, If your fan isn’t kicking on as it approaches 207F, I would suspect trouble. Or maybe it was coming on and you weren’t hearing it? It’s not particularly noticeable.

[Kahoona]

Originally Posted by ualdriver

I have a 2013 Fleetwood Excursion with a ISB 6.7L engine.

I started a thread last summer and received good advice that matched what my mechanic and Freightliner told me. I was driving on a flat road at 65mph. The coolant temperature would slowly rise to the low 200s, the fan would come on (I could hear it), the temp would drop down, the fan would shut off, then the process would repeat. I was told that was normal ops. That seemed weird to me as it wasn’t particularly hot out and the engine wasn’t under a heavy load at 65mph I don’t think.

Anyway, If your fan isn’t kicking on as it approaches 207F, I would suspect trouble. Or maybe it was coming on and you weren’t hearing it? It’s not particularly noticeable.

I bet that you are right! I can't really hear much of what goes on back there. I will have to send the DW back to listen when we hit the Texas Hill Country.

[awol50]

Originally Posted by Kahoona

I bet that you are right! I can't really hear much of what goes on back there. I will have to send the DW back to listen when we hit the Texas Hill Country.

Just make sure and tell her to hang on tight with both hands.

[Kahoona]

Originally Posted by awol50

Just make sure and tell her to hang on tight with both hands.

[scooterbob]

Check out this thread

https://www.irv2.com/forums/f123/cummins-isb-340-engine-overheating-overheat-fan-clutch-thermostat-cooling-etc-230056.html

[Dark Sky]

My 6.7 ISB swings between 194f and 203f. We suffered a Horton fan drive failure on our very first outing back in early 2017, and been trouble free ever since. We don't cruise at 75 mph like you, usually 62 or so. Our Wrangler is about 4300 lbs, heavier than your toad. The engine never feels like its working hard but haven't had it out to the Rockies yet. Hills in Tennessee have been no problem at all with temperature management.
It would be good to hear back from you after the radiator/CAC cleaning.

[Kahoona]

Originally Posted by Dark Sky

My 6.7 ISB swings between 194f and 203f. We suffered a Horton fan drive failure on our very first outing back in early 2017, and been trouble free ever since. We don't cruise at 75 mph like you, usually 62 or so. Our Wrangler is about 4300 lbs, heavier than your toad. The engine never feels like its working hard but haven't had it out to the Rockies yet. Hills in Tennessee have been no problem at all with temperature management.
It would be good to hear back from you after the radiator/CAC cleaning.

HI
We have reduced our speed now that we are over the joy of having plenty of power. Right now we are in CA with the 55mph limit when towing so we do 60. Otherwise we pretty much like 70 max which keeps the wind noise down.

We have not had a problem since the original post. Even in the mountains we don't get over 200. We haven't run into any really wicked heat yet but I am not worried. I have had fan clutch failures on V10 Fords so I know the feeling. I am embarrassed to admit that I have not yet cleaned the radiator. The DW has claimed the under the bed access and crammed it to the top. I have been lazy.

We were on our way to try it out on the big hills in Death Valley but it closed totally just as we got there. I can understand it because of those idiots who wrote on the rocks. I'll post if anything happens. Have fun and remember six feet.