Overheating problems but not in the rain, diagnostic of anything?

My motorhome has started running hot when it really shouldn't be.  Started first on long hills which I wasn't too concerned about but it has gradually gotten worse that now it doesn't need to be much of a hill and harder to get it to cool down.  Had the radiator flushed about 2 years ago, maybe helped a little, but worse this trip so took it too Rocky Mountain truck repair, they did a lot (?) of diagnostics but didn't really find anything so they wanted to flush the radiator.  Let them go ahead a do that, they felt it would help since they got a lot of gunk out of it but as soon as I left, only a 30 minute drive to Loveland and it was running hot.  Now the strange thing is it is not dependent on the outside temperature but it is on if it is raining.  Left Loveland early morning, nice and cool and didn't make it to Cheyenne before it was running hot, at Cheyenne it started raining- engine temperature stayed at 180 degrees all the way to the Tetons!  Same thing leaving Gardiner, WY for Kalispell MT- rained the whole way and maintained 180 degrees with out a budge.  Today went from West Glacier to East Glacier Park on Rt2- cool morning but nice and sunny and had to stop to let it cool down.  Slowing down and down shifting does not help.  Also if I stop and idle the temperature continues to climb, have to shut it down to get it to cool down.  Thanks for any thoughts!

I experienced the same symptoms while en-route to the Black Hills last summer. Got into Rapid City found a Freightliner dealer to look at the problem. They said the radiator needed to be cleaned. Gave them the OK, returned the next day and my DP has run cool ever since then.

Corky

Was the radiator removed, taken apart and dipped?  My guess both places simply ran some cleaner through it.  Which apparently has not cleaned the tubes out.  You need to find a radiator shop that can clean it out

Sorry, got a little distracted with a neighbor who has an arsenal of fireworks. He's testing for the 4th.

My rig is a rear radiator. The rear surface of the radiator is relatively easy to keep clean, but the front facing surface is not so easy. I had been degreasing and power washing the radiator on a regular basis, and thought everything was OK. Obviously just cleaning the rear surface isn't good enough. The guys at Freightliner power-washed from underneath and I think from the inside by removing the access panel under the bed.
After going thru this process once I am now quite confident that I can keep a cleaner radiator on my own.

Corky

What temps do you call HOT??>>>Dan

Utclmjmpr said:

What temps do you call HOT??>>>Dan

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For me the rig went into safe (limp) mode.

Corky

I had tried pressure washing myself (side radiator) from the outside and went underneath to get the inside as best as I could.  That didn't help, at the truck shop they did take the radiator apart, don't know about dipping.

By hot- my normal running temperature is 180, I stop and let it cool down when the engine temperature is starting to go over 200 and the coolant temperature is hitting 230- that's pushing it more than I like.

If it is the radiator would that cause the difference when it rains?  I mean it is QUITE a difference!

Sure would, evaporating water carries away quite a bit more heat than dry air.  That's why people would set up a sprayer to wet down their radiator when crossing the desert in years gone by.

Ah ha, thanks Lou, that explains it!  Guess I'll look for a radiator place, just surprised previous cleanings didn't make a difference but I guess if there is some inner tubes blocked...
Thanks all!

Anybody know a good place on the east side of Glacier National Park?

I found that rain did make a big change in the temps, and quickly.

Good luck.

Corky

Water is a much better "Coolant" than Air. so my first guess would be a dirty Radiator as well. Flushing cleans the INSIDE but you also need to clean the OUTSIDE

One way to do that is to back flush (With Water)

I have an air conditioner I may need to do that too. It looks clean at first glance but it willb e next week before I climb up on the roof again.

It won?t cool down at an idle? That?s really unusual. A 75% plugged radiator will cool the engine at idle. Makes you wonder if fan is pulling any air at all through radiator. Hopefully, fan is coming on at correct temperature. I?m not sure of accessibility on a motorhome, but in heavy duty trucks, we always started with an infrared temp gun for trouble shooting. Check temp on both sides of thermostats, top and bottom of radiator, temp at fan sensor, inlet and outlet of water pump, and ect. Usually doesn?t take long to pin point problem.

Thanks, I know when they flushed it a month ago they did say there was a 90 degree temperature drop but not sure exactly from where to where.  I'll be sure to be more through at the next place.  At least I have a better idea what to ask!

Thanks!

I was able to get the motorhome into a cummins sales and service shop, they were able to determine the radiator is fine but the fan is not coming on.  They hooked it to a computer that tricked it into thinking it was over heating and it said that up front the motorhome thought the fan had kicked on but it hadn't so they thought it was in the hydraulic line to the fan that the message wasn't getting there but they were unable to trace the line so they sent us to a Freightliner place.  They think the line is fine but that the hydraulic pump is bad because the lines that carry the oil never get hot so they want to replace the pump.  Does that sound like a good possibility?

Thanks for all the help!

vetmom said:

I was able to get the motorhome into a cummins sales and service shop, they were able to determine the radiator is fine but the fan is not coming on.  They hooked it to a computer that tricked it into thinking it was over heating and it said that up front the motorhome thought the fan had kicked on but it hadn't so they thought it was in the hydraulic line to the fan that the message wasn't getting there but they were unable to trace the line so they sent us to a Freightliner place.  They think the line is fine but that the hydraulic pump is bad because the lines that carry the oil never get hot so they want to replace the pump.  Does that sound like a good possibility?

Thanks for all the help!

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I?m pretty sure the hydraulic pump also powers the power steering. If that?s correct and since I assume the steering is fine, I would suspect the hydraulic fan motor first. I think you?d also want to check to see if the ?turn on? signal is reaching the fan. Not sure I?d throw a hydraulic pump at it just yet. Caveat: definitely no expert in this area.


(It doesn?t sound as-if Freightliner is certain about the diagnosis, I?d ask them what if they?re wrong about the pump, who?s paying for the parts and labor?)

Sun2Retire said:

I?m pretty sure the hydraulic pump also powers the power steering. If that?s correct and since I assume the steering is fine, I would suspect the hydraulic fan motor first...

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You are correct. The same hydraulic pump is used to drive the fan and run the power steering. If the steering is OK, the pump is fine.

As usual you all are correct!  Now I'm feeling pretty dumb saying this but I kind of always assumed or didn't really think about it,( just thought that was the way it is) that it didn't have power steering.  Since we got it 6 YEARS ago it was our first motorhome and well, it's big and hard to turn.  I'm the driver and my husband the director, so when backing up he'd be yelling at me to turn the wheel first and I'd be yelling at him that the wheel won't turn until it's moving at least a little and still difficult if moving slowly.  I guess he must of been thinking I was a weakling.  Anyway it was just for parking, going down the road was not an issue.  Also I guess most of the time it didn't need the extra cooling of the fan cause now I am assuming it has always been without it since we've had it.

So they spent all day Friday tracing the lines and valves making sure no blockages in the hydraulic lines.  They were all fine so took the hydraulic motor off and sure enough it doesn't turn properly.  So by then it was too late to find a new motor and it's Canada Day weekend.  They take that very seriously up here!  So the motorhome is not moving, locked up in their shop, we are at a motel and they don't open back up till Tuesday!  I'm just hoping they can get the motor quickly, I'm missing my reservation at Banff (((.  Sorry just had to vent a little.  They're doing a good job just a bad weekend to do it, we just had 6 free days so thought would be a good time to take care of it thinking it would be a few hours job.  Boy were we wrong.  Well really looking forward to having power steering!  I imagine I'll be whipping it into parking/camping spots in no time now!

WOW you're killing two birds with one stone, good deal!  Glad to hear you've found the problem.

As for Canada Day...we found out about it the hard way too. On our first trip into Canada we showed up in Calgary on Canada Day and guess what.  No campground space  available anywhere. 

Wound up going clear to Edmonton before we found a RV space.

Haha, yes but I'm afraid it's going to cost for both birds!

Yeah, before we knew it was going to take so long I think I found the last camping spot in Alberta for the weekend!  (Lost the cost of that too since didn't know till Friday that wouldn't be making it.)