2006 itaska horizon 400 cummings getting hot

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billy burnett

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I have a 2006 itaska horizon 400 Cummings and the motor home has the radiator on the side. It is getting hot when going on inclines and I have to manually down shift sometimes to 1st gear. I have had it in Cummings in Denver, Dallas, And Grand junction to fix problem but they put it on machine and tell me nothing wrong. Please I need help with problem. Thanks
 
I don't know what temps you are seeing, but I have a 450hp Cummins, rear radiator, and was having some overheating issues on hills. Freightliner told me I need to run at peak horsepower, around 1700 rpm minimum, and to downshift to keep the RPM's up, engaging the fans and water pump at a higher rate. I was typically running at 1500 rpm and not shifting.

Following their recommendations, I have not seen the issue. I will still get a bit of temp spike on a long grade but it goes down when the thermostats open and fans cool. My normal cruising temps are around 180 on the engine and 170 on the transmission.

I have seen posts about issues with side radiators, but someone else with that configuration would have to tell you about that. If your radiator is good and clean and your coolant is at the correct level in the correct mix, the engine speed may be an issue.
 
billy burnett said:
I have a 2006 itaska horizon 400 Cummings and the motor home has the radiator on the side. It is getting hot when going on inclines and I have to manually down shift sometimes to 1st gear. I have had it in Cummings in Denver, Dallas, And Grand junction to fix problem but they put it on machine and tell me nothing wrong. Please I need help with problem. Thanks
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The first thing I would do is take it in and have the exterior of the radiator steam cleaned, both sides. I had the same problem with my DP with a rear radiator and that fixed the problem. Rear radiators are more likely to get dirty but side radiators can too.
 
What sort of temperatures are you seeing? My ISL 370 typically runs at 185-188 but can easily climb to 200 or so in some operating conditions. That is well short of "hot" for the ISL.

The transmission can also cause a rise in temperature. My Allison 3000 normally stays below the engine temp, but once in awhile I see it go past the engine and then begin to "pull" engine temps up along with it, as the tranny dumps its excess heat into the radiator.

It's pretty rare for a side radiator to get dirt clogged, but it's still a possibility.
 
I have literally years of experience with the same issue and have the same engine/chassis/cooling pack as yours.

Did any of those shops check your fan RPM?  Freightliner has RPM specifications for the hydraulic fan - a few years ago Freightliner in Tolleson (Phoenix) checked our fan RMP RPM and it was below spec so they replaced the hydraulic fan and fan hydraulic pump (your radiator fan is operated by a hydraulic motor.)  Speaking of the fan, it cuts in at either 215 or 220 degrees depending on who you ask.

Freightliner factory service says there's no need to steam clean a side radiator, but Freightliner in Tolleson thinks that's important, so they did ours last fall with a major M3 maintenance.

When pulling a long grade you need to adjust your gear selection and speed so that your engine RPM is 2,000 or above.  You need to actively manage engine RPM - your rig is not like a car.

Your engine will derate at 235 degrees so keep your coolant temperature in the 215-220 degree range - you might be at 2,000 RPM and going 35-40 MPH but that's the situation that you have to deal with.

It is my opinion the cooling pack on that chassis is marginally sized - there is not enough cooling capacity.

Oh, by the way - it's spelled Itasca and not itaska.
 
Thanks for info on Freightliner. I have owned my RV since new in 2006 and it has 60,000 miles.  I always gear down and do no let it get hot but just wondering if anyone else had the same problem. I ask about speeding up the rpm of the fan but was told it could not be done.  All the answers came from Cummings.  The only freightliner shop I was in told me it was Cummings. Thanks for your info. I will follow up on it.
 
Ran into a couple that had the side radiator on their Winnebago, and were having overheating issues, turned out to be there was a lot of dirt build up on the radiator. It seems that the dust etc kicked up by the tires was the issue. After they had the radiator cleaned no more overheating issues.
 
Speaking of the fan, it cuts in at either 215 or 220 degrees depending on who you ask.
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I think you mean 115? In the side radiator configuration on an XC chassis with an ISL engine,  the fan comes on at partial speed at a low temperature to provide cooling for the charge air cooler (CAC) and a/c heat exchanger. It is a variable speed fan, so the speed increases as heat demand goes up. I don't think it uses the one or two speed fan typical of rear radiator configurations
 
Hmm. Mine (also Freightliner) comes on at 115 and increases speed as needed under ECM control. If it took 215, my fan would never run!  Maybe the Winnie's don't have the variable speed fan? But then what provides cooling for the CAC?

Sorry - don't mean to digress from the original question.
 
Dunno Gary - I've never gotten that far into the details of the cooling system.  There might have been an emissions change for 2005 since our engine runs at 200 degrees, engines had to run higher temperatures and higher fuel injector pressures to meet emission requirements.  The older diesels would run (I think) in the ~180 degree range.

Off and on I have this fantasy about going to a Cummins dealer or truck shop and asking about a re-engineering of our cooling system, maybe even a larger radiator or one with more rows or cores would be an improvement.  Last year we were at Cummins of Tolleson (Phoenix) getting an ECM update and there was a guy there in an older Country Coach  getting a new radiator - it had to be custom made and I think the radiator cost was about $3k.
 
John Canfield said:
Dunno Gary - I've never gotten that far into the details of the cooling system.  There might have been an emissions change for 2005 since our engine runs at 200 degrees, engines had to run higher temperatures and higher fuel injector pressures to meet emission requirements.  The older diesels would run (I think) in the ~180 degree range.

Off and on I have this fantasy about going to a Cummins dealer or truck shop and asking about a re-engineering of our cooling system, maybe even a larger radiator or one with more rows or cores would be an improvement.  Last year we were at Cummins of Tolleson (Phoenix) getting an ECM update and there was a guy there in an older Country Coach  getting a new radiator - it had to be custom made and I think the radiator cost was about $3k.
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John, I'm still learning my Allure but after cleaning the cooling pack today, I am really liking the side radiator configuration.  Basically, there seemed to be no dirt and grime in what came out.

Regarding CC radiators, I'm learning that CC used aluminum radiators for a number of years and many owners had failures.  I'm lucky that my coach has the real deal...copper cores (I think) and brass tanks.  I do notice, however, that my fan comes on as soon as the engine is started.  When I had the coach into the local Cummins Coach Care center recently for chassis service, I asked them to check on that and they said all was well.  Mine is one of the 2007 'clean diesels' so maybe they all do that.

 
Gary - side radiator is the way to go assuming it's properly designed.  Here's a good thread about overheating on the ISL on a Freightliner chassis.  The radiator might need to be increased in size from 1050 sq inches to 1200 to truly mitigate the problem.
 
One item to check for is a cracked Charge Air Cooler that has the crack directed towards the radiator. Hot air from the CAC blowing onto the radiator can raise the temps pretty high, and not always detectable during normal hi-way driving conditions. The Cummins shop here could not find a replacement for mine, so I took it out to the Base, and re-welded it myself, and even had my bill reduced by $200.00. The only way it was found was on a chassis Dyno, and under load.


Lee
 
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