2001 Zephyr (Allegro bus) ISM 450 overheating issue, side radiator

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jgammill

New member
Joined
Aug 3, 2021
Posts
2
Location
oklahoma
I've owned this coach for the last 4 years now. We take a yearly vacation to the same location in Colorado every summer. The first year there was no problem. Every year since, it seems to heat up easier and easier. I do have 4 miles of dirt road to travel every time I leave my house. But I wash the radiator out all the time. I replaced the thermostat and that didn't help. This year I noticed a sound and found the bearings on both fan hubs were dry and stiff. So was the idler pully and tensioner. I replaced all of that and now it spins freely. I figured that was slowing the fans down enough to cause the problem. But it didn't seem to help one bit. I noticed on a friends coach he has a full piece that covers from the bottom of the radiator all the way under the other coolers, i.e. intercooler, oil cooler, condenser. But mine is all open. I would think that only makes it not pull air through the other coolers as much but the radiator is still getting plenty of air? It's been that way since I bought it. My other thought is I know back when I first got it, when you turn the AC on it seemed to speed up the fans, even at a stand still. But it doesn't seem to do that anymore. Is there a sensor somewhere I need to check. It also has an electric fan mounted to the outer most cooler that doesn't seem to be working. Is that part of the same sensor? This is a dual fan setup driven from a single hydraulic motor. My only other thought is to pull the radiator and take it to a shop to be gone through. The coach only has about 60k on it.
 

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webber46

Well-known member
Joined
Aug 11, 2013
Posts
186
Location
Rockford, IL.
Before you go any further, you may want to look on the BACK side of the radiator and make sure it is clean. I say this because I had a overheating problem with my Cat 350 last year and found that the blow-by hose on the engine was omitting drops of oil that were being blown back and hitting the radiator, causing it to be blocked with the oil and dirt on the back side. I too cleaned my radiator regularly from the outside. The fix was done by a Wyoming Cat Dealer with a 2" extension hose to the back of the MH, thus bypassing the radiators. Just a thought.
 

jgammill

New member
Joined
Aug 3, 2021
Posts
2
Location
oklahoma
Before you go any further, you may want to look on the BACK side of the radiator and make sure it is clean. I say this because I had a overheating problem with my Cat 350 last year and found that the blow-by hose on the engine was omitting drops of oil that were being blown back and hitting the radiator, causing it to be blocked with the oil and dirt on the back side. I too cleaned my radiator regularly from the outside. The fix was done by a Wyoming Cat Dealer with a 2" extension hose to the back of the MH, thus bypassing the radiators. Just a thought.

Thanks for the reply. When I was in there replacing the fan hub bearings I had the fans and shroud off and could see the entire back side of the radiator. I was even able to use a power washer to clean it from the back side. There was no major residue on it. My blow by tube runs down the side of the motor and the air from the fans is always blowing it away from the radiator anyways.
 
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