At My Witts End

[markortega]

I am reaching out to all you RV Veterans because my RV keeps overheating. I have a 2008 Fleetwood Discovery 39R with only 20k miles. The RV is currently at Freighliner. This is the second time since November it has been there. First they replaced the Engine Harness and the Temp Sensor, this took two weeks to complete. On this visit they have replaced the Thermostat. Monday will be another two weeks they have had it. After speaking with their foreman today, they say it does fine on flat surface but overheats on any grade. Any ideas? I'm at the end of my rope and checkbook?

[oldmattb]

Long shot idea. Bad radiator hose. When cool, the hose is somewhat firm and retains shape. When heated by coolant, it becomes very pliable and collapses from water pump suction, cutting off the flow of coolant.

Matt B

[wolfe10]

Good advice, EXCEPT: Don't use Simple Green.

Use Simple Green EXTREME. It is aluminum friendly. And your CAC is aluminum.

To verify, when it is dark out, access the top of the engine. Shine a strong flashlight into the fan shroud/between fan blades. Verify that the perimeter (the fin slings dirt to the perimeter) is a clean as the center. Pay particular attention to the lower perimeter.

[DSDP_Don]

This is a typical symptom of a dirty radiator. Fine on flat land, overheats on the hills.

The problem with coaches that have the Charge Air Cooler (CAC) and radiator sandwiched together (Freightliner) is that they get very dirty between the two and it's really hard to see. Many require quite a bit of bedroom disassembly to get to the center of the two. Even then, there is so little room that it's a tough job to clean them. I'll bet if you look, it will look like hair is growing between the two.

[hershey]

Its a very well known fact that the rear radiator on a Cummin's engine will plug up. Mind did at 30,000 miles. This is not all that hard to see if you can do your own PM on it. Find a car wash that the rear of the MH will fit into. Saturate the radiator with Simple Green. Use the power wash to flush the gook out of the radiator. Make sure you keep the spray directed directly into the fins and don't bend them. If you can, get under and spray the engine side of the radiator also but don't get close to the fins with the nozzle so you don't bend them. Then make sure the slobber tube has a hose connected to it and routed down and under the radiator.

[MaverickBBD]

I had the slobber tube extension installed two year ago when I was at Gaffney. Their suggestion because I always had them wet steam radiator and CAC. This past Oct. I got a high temp alarm while going "over the hump" from Parumph to LV. Okay it was probably 100 degrees outside and I was sparing the horses but thought I was keeping the r.p.m.'s high enough. I backed off and alarm cleared but I also reached the summit. It was all downhill from there. I did some research and am leaning toward still picking some 'junk' up between CAC and radiator. Hoping to get to Gaffney in the spring and we will see what we find.

I find it interesting they when the electric route first. I would have started where the physical act of cooling is initiated and worked back from there.

[bullydogs1]

The rear radiator needs to be cleaned with simple green....

[azrving]

It doesn't seem old enough to be suffering from core fin separation but it may depend on the environment it has lived in. If the fins lose their bond to the tubes in the radiator core they will not transfer enough heat out into the fins/air. I have seen it a few times but it's usually on older equipment. Usually starts at the lower sides. The fins will easily pull right off the tubes. Real bad ones will just flak apart. The complaint was the same as they described.

When did this start was it gradual or more sudden?

[Trackrig]

Should we assume there is slobber tube installed? After asking that, my 2005 Fleetwood Excursion (same thing as the Discovery) has a Cat C7 and needs the slobber tube. You may have the Cummins which I don't know if it needs one?

Besides that issue, have they cleaned the radiator and CAC?

Bill

[traveylin]

interesting that they would change out the engine harness first, Did they have data from the control module that it was a load problem or a heat rejection problem or a bad instrument reading. If your gas milage is typical/normal I think Moses lake has pretty good input. Does transmission temperature track that of the engine. If so then instrument bad may be ruled out.

[w4phj]

Dirty CAC?

[enblethen]

What type of fan system is on your rig?
Is it on the engine, hydraulically operated or electrically driven? Could be it is rotating in the wrong direction.