Itasca Horizon overheating

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ste1148watt

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re: 2005 Itasca Horizon with ISL 400 and side radiator. I have always had some issues with it wanting to overheat. New radiator, fan checked , etc. Some Horizon models have a rear radiator and two electric fans blowing on the a/c condenser. Any thoughts on adding these fans on the side radiator to aid in cooling?
 

Gary RV_Wizard

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Side radiators are supposed to eliminate the airflow problems of a rear radiator, so adding fans is a band-aid at best.

Could you describe your "wanting to overheat" problem further? Is it always hot, or only at times, and how hot? What temperatures under which conditions, that sort of thing. Big diesels run hot and allow the temperature to vary more widely than gas-engine cars. And they typically rely on the cooling fan speed rather than a water thermostat. The thermostat opens wide at a low temperature and stays that way.

The dash a/c condensor has a large effect too. In most such systems, if the a/c is on the fan runs constantly at least at a low speed. Coolant temperatures may actually fall a bit when the a/c engages.
 

ste1148watt

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Normal operating temp is 200-205 on level terrain. On long inclines the temp will start up to 215-220 range where I will downshift to raise rpms (2000) . Temps will come back to the 200 area. Apparently this is a problem with these model MH. I think John Canfield experienced the same issues with his Horizon.
I thought the fans might help with more airflow and help with temps. I dont think they could hurt anything. Its just a PIA shifting back and forth.
So much for automatic.
 

John Canfield

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I had overheating issues from early on in my Horizon ownership. A few bullet points:

- engine will derate at 230F (or 235F, forgot which) saving the engine from overheating

- keep engine RPMs at or a little above 2,000 RPM, downshift or slow way down as necessary to keep temps below 230F. In Colorado on mountain roads I would be running at 30 MPH

- engine is prone to derate at high altitudes, high air temps and a grade (and pulling a load)

- have a Freightliner Oasis dealer check cooling fan speed vs engine RPM. My fan motor and fan pump was replaced due to not meeting specifications

- I think there is value in having that side radiator professionally steam cleaned. I would frequently shoot a degreaser into the side radiator, let it sit for a minute and rinse off with a mild pressure washer spray (note the MILD qualifier). The outer 'radiator' is actually the dash air condenser coil

I seriously doubt trying to add fans would be either practical or even possible. I was investigating the idea of spraying a water mist into the radiator package but it never passed the thinking stage.
 

Ksouers

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First, diesel fuel contains more BTUs than gasoline plus burns slower and hotter, so getting warmer on long grades is normal. Downshifting is the usual prescription as it puts more torque to the ground and allows the engine to work a little bit less at the cost of slower speeds. It's just the nature of the beast. 210-220 is a normal temperature under a heavy load, such as a hill climb, but do keep an eye on it.

This is a long shot but another consideration is the possibility of cavitation in the water pump. It may have a couple causes, the pump impeller can be turning too fast or a restriction in the water inlet to the pump. Both result in reduced pressure in the pump which allows the coolant to form bubbles that the impeller beats into a froth and reduces the flow of coolant. Keep your engine RPMs around 1800-2000, even if it means reduced speeds. But cavitation will result in significant overheating, so, really I don't think you are having cooling problems. Just need to adjust driving habits to match the situation. But do take heed of John Canfield's suggestions and have both fan and pump checked out by a qualified technician.

Kevin
 

Mark_K5LXP

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It would seem just a basic test of the radiator might reveal if it's that, or something else:

Perhaps the best method of testing radiator efficiency is to measure coolant inlet and outlet temperatures when the cooling fans are activated. A typical measurement might show 200° F coolant entering the radiator and 130-160° F coolant exiting the radiator.

Years ago my pickup would overheat just driving around and by all appearances the radiator was bad. I pulled it out with the idea I'd be replacing it and discovered the fins were jam packed with cottonwood tree fuzz. I pressure washed the fins, reinstalled it and I'm running the same radiator 15 years later.

Mark B.
Albuquerque, NM
 

Gary RV_Wizard

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Normal operating temp is 200-205 on level terrain. On long inclines the temp will start up to 215-220 range where I will downshift to raise rpms (2000) . Temps will come back to the 200 area. Apparently this is a problem with these model MH. I think John Canfield experienced the same issues with his Horizon.
Yeah, that's a little warm for that engine and load. My 2004 Tradition with ISL 400 (Freightline XCM chassis) ran about 190 on the highway and climbed to around 200-206 on grades. Higher on steep or long grades. The fan went to high speed at about 208-210 and the temp dropped rapidly.

If possible, I suggest a trip to the Freightliner Custom Chassis factory service center in Gafney, SC. Those guys know the chassis and cooling system inside-out and I'm confident they could solve the problem.
 

Ray-IN

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When was the coolant system last maintained? Things like thermostat replaced or manually inspected for accuracy, radiator "sandwich" cleaned out using Simple Green Extreme for aluminum.
Also, what is the condition of the serpentine belt? If it is original it may be worn enough to slip. Most auto supply stores have free gauges to check them.
 
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John Canfield

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Yeah, that's a little warm for that engine and load. My 2004 Tradition with ISL 400 (Freightline XCM chassis) ran about 190 on the highway and climbed to around 200-206 on grades. Higher on steep or long grades. The fan went to high speed at about 208-210 and the temp dropped rapidly.

If possible, I suggest a trip to the Freightliner Custom Chassis factory service center in Gafney, SC. Those guys know the chassis and cooling system inside-out and I'm confident they could solve the problem.
I believe the root cause of these cooling issues is Freightliner didn't spec the cooling pack properly for this chassis series with the ISL. Some of these S Bodies (Vectra/Horizon) came with a Cat C7 and I've never heard any cooling system reports from this combination.

Another vote to take your Horizon to Gaffney.
 

Gary RV_Wizard

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I believe the root cause of these cooling issues is Freightliner didn't spec the cooling pack properly for this chassis series with the ISL.
My guess as well. The 370 hp version of the 8.9L ISL in my 2004 XCM chassis does fine and it's the same radiator and coolant fan. The 2005 Horizon with the 400 hp ISL would likely run a bit hotter, and/or perhaps the XC chassis has a little bit different air flow characteristic.

I would think that the ECM could be programmed to increase fan speed a bit sooner to compensate.
 

John Canfield

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My guess as well. The 370 hp version of the 8.9L ISL in my 2004 XCM chassis does fine and it's the same radiator and coolant fan. The 2005 Horizon with the 400 hp ISL would likely run a bit hotter, and/or perhaps the XC chassis has a little bit different air flow characteristic.
The Horizon chassis is the "Evolution" with IFS (independent front suspension) so there's probably cooling package differences.
Thanks for everyones's input.
Sorry there wasn't a silver bullet for the problem but at least you have a few things to ponder.
 

cbeierl

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Not according to the '05 Itasca Horizon chassis specs shown on the FCCC website, but those aren't always 100% accurate because the coach builder may change the specs on a subsequent order.
John is correct, all of the 2005 and subsequent Vectra/Horizon models have the Evolution chassis with IFS (despite the 'Built On Freightliner' info for 2005 which indicates a solid front axle for some). It's possible some of the 2004 ones lack the IFS, but I'm not sure.
 
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