Over heating problems

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banjo5491

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Jan 19, 2010
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SE Minn
I have a 07 Tour on a Freight liner chassis with a 400 hp Cummings engine. There our times when on the road the engine temp will run 210-212 degrees and some times cool down to the 190?s. I have been told the problem is the fan clutch,my local dealer said it does?nt have a fan clutch. Can anyone tell me ,what is what,       
With the fan clutch and other possible solutions I should consider.
 

ChasA

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Mar 21, 2009
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I don't know if your engine has a fan clutch but my 6.7 does. One thing I know for sure though is you don't have a Cummings engine. What dealer are you talking about? An RV dealer?
 

Top38

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Oct 26, 2009
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114
If it runs warmer under heavy loads such as long hills then I'd say you need to have the radiator/intercooler cleaned as they get clogged up over the years with engine grime. If it has nothing to do with engine load then it could be a number of things like a clutch fan or sticking thermostat.
 

ste1148watt

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Mar 24, 2017
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59
As they say ?been there, done that.  I have the exact problem on an 05 ISL 400. Even with a new radiator , thermostat and cleaning still have the overheating on long hills. Only answer I have found is to keep the rpm around 2000 and/or slow down. I?m convinced the radiator is too small for the unit although Freightliner will never admit to it. I doubt you have a fan clutch, most fans are run by hydraulic pumps on this model. Hope this helps . I think John has the same issue on his .
 

cerd

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May 29, 2018
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MN
I don't know anything about Diesels, but on all of my gassers, 210 is normal. The thermostats are rated for 190, but that doesn't mean that it will keep it at 190. Conditions such as high heat and low airflow from stop and go road conditions, for example, will make it go a little higher.

If you are worried about it, change the fan clutch. I think you will be fine though. When your fan goes, it will be a significant difference...like 230+, causing you to pull over and let it cool down.
 

John Canfield

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Texas Hill Country
My engine exhibited similar cooling characteristics when the Freightliner dealer forgot to plug in my fan controller after an engine head job. Coolant temps went down along with MPG. Since he has a rear radiator, he has a mechanical fan clutch that might be locking up cooling the engine down too much.
 

Utclmjmpr

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Cedar City, UT
If your right John,, then he has also had a dive in the mileage and hasn't noticed it.. It isn't difficult to open the hatches and take a look at things to determine if he is getting the truth.>>>Dan  ( Banjo,, Look up the life of Clessie Cummins,, a very accomplished person in American history)
 

Five2o

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May 8, 2011
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57
I have the 400 ISL in my Ellipse...temperature often goes up as high as 212-216 at which point the fan kicks in, before falling back to 195 or so in hot weather & steep climbs since I bought the rig 10 years ago. I'm usually too lazy to gear down etc so just leave the rig on cruise control & let the Allison decide how it wants to climb.. Freightliner tech says its all normal...I've got 136000 miles on her so I guess everything is OK.
 

ste1148watt

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Mar 24, 2017
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I have always had trouble with my ISl 400 (side radiator) tending to overheat.  Manually keeping rpms around 2000 helps but what a pain.  Our recent trip from Vancouver to Dallas , I removed the rear rock guard,  not the ones behind the tires, and the temps came down to a consistant 200-205 without manually shifting to a lower gear.  Seems like the rock guard was creating an air dam and not letting the air  pass though as intended.
 
 

John Canfield

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ste1148watt said:
I have always had trouble with my ISl 400 (side radiator) tending to overheat.  Manually keeping rpms around 2000 helps but what a pain.  Our recent trip from Vancouver to Dallas , I removed the rear rock guard,  not the ones behind the tires, and the temps came down to a consistant 200-205 without manually shifting to a lower gear.  Seems like the rock guard was creating an air dam and not letting the air  pass though as intended.
Ah-ha!
Your logic makes a lot of sense, mine is coming off. It's all beat up anyway.
 

cerd

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John Canfield said:
Ah-ha!
Your logic makes a lot of sense, mine is coming off. It's all beat up anyway.

I would be concerned about debris hitting the radiator. Is there something else to keep it from getting damaged? If not, you way want to consider some kind of screen for it...expanded steel grate perhaps.
 

John Canfield

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That's a possibility I suppose,  the disadvantages of that flap far outweigh any advantages. When we used a tow shield on front of our old Jeep Liberty toad, the flap would kick up rocks, the rocks would hit the toad shield and ricochet into the back cap. When we got back from Alaska I noticed maybe 50 gel coat dings where the paint was chipped off.
 

k9cop

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Jan 6, 2009
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ste1148watt said:
I have always had trouble with my ISl 400 (side radiator) tending to overheat.  Manually keeping rpms around 2000 helps but what a pain.  Our recent trip from Vancouver to Dallas , I removed the rear rock guard,  not the ones behind the tires, and the temps came down to a consistant 200-205 without manually shifting to a lower gear.  Seems like the rock guard was creating an air dam and not letting the air  pass though as intended.

When I get my RV back, I am going to look for the rock guard that you are talking about. The only rock guard I knew about was the ones behind the wheels.
 
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