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thomandcoley

Cummins 6.7L overheating issues Forest River Berkshire 2009

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I have a 2009 Forest River Berkshire Class A diesel pusher with a 6.7L Cummins that keeps overheating. In the past month I have:

First, Had the rear radiator blown out with air and then pressure washed. Lots of black filthy water came out. 

Still overheating. Then:

1. Had the Turbo replaced ($3400 rebuilt part-if you get one BE SURE it comes with the actuator) and the exhaust fixed where it had come loose and had it re-milled to fit better. $2800 labor. The tech showed me the turbo and it was definitely jammed up and not able to spin freely.

Drove away, still overheating. Returned and then:

2. Had thermostat replaced $551

Drove away, still overheating, took it back third time and then:

3. Had a re-gen done on the catalytic converter

4. Replaced the air filter - it was filthy and jammed up with dirt

Did all that at a place called Ross Point Truck Repair in Post Falls, ID. Drove away, still overheating. SPENT 4 WEEKS THERE!!! STILL NOT FIXED!!!

5. Had the inner cooler or CAC sprayed out with water

Took it to Western States in Spokane WA and they hooked it to the computer and said it was not showing any codes. 

If I downshift all the way to 3rd, 2nd or 1st on my Allison transmission, and get the RPM's up to like 2700-3000, it still gets hot but doesn't overheat. Of course, I can only go like 30-45mph.

Doing lots of mountain driving in the next week. My wife and I travel for work, so if we are stuck somewhere not moving we are losing lots of money. 

A few folks have suggested the water pump. Another guy said maybe it's a sensor, but it mainly overheats on big hills. ALTHOUGH, it has overheated on flat ground towing the car about 15 minutes in to the trip. Our manufacturer says we should only tow 5000 lbs, our car is 6000, every mechanic I have talked to says the Cummins 6.7L should tow 10,000 lbs with no issues. 

We have had this rig since Oct 2017 and towed the car at least 7000 miles with no issues. 

It's not losing any water when it overheats.

Engine oil level looks good.

Transmission fluid is clear, full, and does not smell burnt. 

ANY IDEAS????

 

 

 

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Not knowing what type fan your coach uses, but if it uses a clutch, that would be my first replacement. Just the clutch. I have also seen occasions where someone added the wrong type anti freeze, which caused coagulation, in this case the entire system had to be flushed and filled with the correct anti freeze. 

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Let's start with the facts-- how hot is it getting?

#5 would be where I would start.  The VAST majority of the dirt and debris will be on the front of the CAC.  If there is any oil residue, water alone will not clean it properly.  Simple Green EXTREME was developed for degreasing aluminum airplanes, so is safe to use on aluminum CAC's.  It must be cleaned from the front-- meaning the bedroom or closet.  What ever offers access to the fan shroud. 

Yes, you could CAREFULLY cut a hole from below in the fan shroud that you would plug after the cleaning to access this area from below.

And, absolutely verify that your clutched fan is operating as it should.  It should be a low/high, not off/on and you will need to verify that indeed it does kick to high when operating temperature goes above thermostatically controlled temperature.

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The mechanic said he thought the fan clutch was operating properly, but they only tested it sitting still and not under a load on the road. 

When it gets to 225, the overheat warning buzzer comes on. Usually we pull over and let it cool down once it gets that hot. One time I did this and the temp got all the way up to 248.

When I gear down, the temp goes down fairly quickly - sometimes. If I'm not on a huge hill. 

Before all the overheating began, it would run about 194 - 201 

We had a couple days after the repairs where we drove it mostly on flat ground, pulling the car, and had no issues. But then on another day about 10-15 minutes in, it overheated going over a long flat bridge. 

 

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My motor home has had an overheating issue for several years. I had only been cleaning from the inside; but at the Gillette Convention, the Freightliner tech said I was doing it correctly. But he stated that the dirt I was washing out was collecting in the bottom of the fan shroud. When dry that dirt was clogging the radiator. He wanted me to do two more things. Cut a 1-1/2” hole in the bottom of the fan shroud as close to the radiator as possible without hitting it. Clean from the inside as I had been doing then from the outside using a pressure washer set in a fan pattern, not stream, and from about 2 feet start at the upper left corner and work to center then upper right corner to center. I put a bucket under the hole and was very surprised about how much dirt was collected in the bucket. I cleaned with the power washer ($89.00 1,650 psi) for an hour until I got tired. Came back and did another hour. Quit and did another hour until I got clear water in the bucket. 

I drove to a chapter rally and for 50 miles drove st 70 mph. Before I could not drive for 35 miles at 62-65 mph without the check engine light coming on.

When I returned home, I cleaned with the power washer again for 2 one hour sessions. Again the bucket finally had clear water.

 I have decided that after every short trip, I will pressure wash from the outside, and twice a year I will clean from the inside.

Hopefully, my experience will help you.

 

 

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Lots of talk online about that engine with overheating issues. Aside from what the others said, I'd be curious about the condition of the belt running the water pump as well as the water pump itself. If downshifting (increasing engine RPMs), then perhaps the water pump is not pumping adequately at slower RPMs which might indicate a water pump issue.

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3 hours ago, wolfe10 said:

#5 would be where I would start.  The VAST majority of the dirt and debris will be on the front of the CAC.  If there is any oil residue, water alone will not clean it properly.  Simple Green EXTREME was developed for degreasing aluminum airplanes, so is safe to use on aluminum CAC's.  It must be cleaned from the front-- meaning the bedroom or closet.  What ever offers access to the fan shroud. 

My money is on this or a faulty clutch fan. A through cleaning is step #1 and by far the most cost effective. A water pump could be an issue if the engine wasn't properly maintained prior to you purchasing it, like high PH deteriorated the impeller. 

Curious, when you hit those temperatures above 225 did you happen to hear the fan, it should have been loud roaring back there will all of that heat hitting the thermostat on it. 

 

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Fan clutches have evolved over the years. There was a time when clutches were fail safe engaged . No power because of a broken wire , the fan clutch was engaged all of the time  to allow the engine to cool. Then there was a wave of the reverse for awhile. Learned that on a cold winter snowy night in western Colorado. Ascending Vail Pass and the engine overheated. Pulled onto the shoulder, collected my thoughts, climbed down out of my cab over, walked into the front of the rig, and low and behold the fan was not running though the engine needed some cooling. The rest is me describing how I solved the problem. Tune out I If you are bored, but my point is that you may think that your engine fan is on when it is not. 

 

Now the The Rest of the Story/ I had to jack up the cab to gain access to the engine. I quickly found a broken wire atop the valve cover headed to the fan.. A crimping tool and the proper connecter installed, problem solved. There is nothing like having several thousand pounds hanging over  you while big rigs go by slipping and sliding. Could have been a career ending event.🙄.

 

 

 

 

 

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As Joe says, water pumps do fail. Normally after many miles.

You mentioned a big rise in temp on a flat bridge. If  you DO have a properly functioning fan clutch, over heating on a flat surface would be quite unlikely. Unless of course the engagement point is far above normal. Just a thought/ could there be a problem with the ECM? I lost one on my last big rig, but it was sudden. Maybe they  could act up in bits  and pieces. Just throwing it out there.

Everything was fine for quite awhile and then problems started suddenly?

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No, the problems have been happening for a few months - we have had a hectic schedule - we travel full time in our RV for work, not pleasure - and have had limited time to get it into a shop. The overheating was a gradual problem - it got worse over time. 

Never heard a loud roaring from the fan when it overheats, but it's like a blast furnace blowing hot air behind the rig where the radiator is. 

Looked at inner radiator today from bedroom access hole, visually it does not look filthy dirty but hard to tell if there's junk inside it. 

At Cummins Salt Lake City today for another diagnosis, they have all the paperwork from the last shop, hopefully they will nail it down this trip. 

 

 

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28 minutes ago, thomandcoley said:

Looked at inner radiator today from bedroom access hole, visually it does not look filthy dirty but hard to tell if there's junk inside it.

 

 

Often looking at the front of the CAC from the bedroom CAN be deceiving.  What is easiest to see is the CENTER where the fan blades are less of an obstruction to your view.  But, the fan blades "sling" the dirt to the perimeter, particularly the lower perimeter.  What you need to do is confirm that the lower perimeter is as clean as the center of the CAC.

I have had people use a small camera to verify and the results can be shocking-- I still use one picture sent to me in my "Diesel Maintenance Presentations".  A clear example of it is clean-- O, all I looked at was the center.  Whole lower section completely blocked.

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Brett --

For owners like me who are still in "Motorhome Pre-K" and have spent essentially no time under the rear end of their motorhomes, can you provide a photo and/or image of a charge air cooler so we know what we're looking for on our "rear radiator" motorhomes?  The only image I can find is attached which isn't overly helpful.

Also, if the charge air cooler must be cleaned by removing the engine compartment access panel in the rear of the motorhome, what do you use to clean the charge air cooler?  A small garden sprayer perhaps?   Do you dilute the Simple Green cleaner?

Thanks for the help and education!

 

 

Charge Air Cooler Diagram.jpg

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Mike,

Sorry, not at home so no picture.

But yours and the vast majority of other DP's have  SANDWICHED cooling systems.  Air enters the fan shroud, the fan pushes it into the  CAC (first thing in the air flow-- it is what you see from the FRONT/bedroom or closet access when looking into the fan shroud.  Easy to tell as the inlet and outlet are LARGE-- they only carry AIR.

Behind the CAC (toward the rear of the coach and easily seen from the  back, outside of the coach) is the RADIATOR.

Indeed it is a pain to clean the front of the CAC.  Best product is Simple Green EXTREME, as it was developed for degreasing aluminum aircraft and will not harm the aluminum CAC.  Yes, you could use a small sprayer or just put some in a small spray bottle which will likely be easier to maneuver around the fan blades.

That and a garden hose with garden nozzle and be sure to wear OLD CLOTHES and cover the area around the the opening so Cindy doesn't put you in time out.

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Mike, This is a picture of the CAC / Radiator stack configuration.

CAC / Air Cooler is the top / smaller "air to air" radiator and the larger / bottom  portion is the coolant radiator.

Rich. 

 

IMAG0129.jpg

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OK, this is the picture of the "clean" CAC.  Yes, when looking from above, the CENTER (yes, the clean area) was the only easily visible area.

But, this picture tells the story.  YES, it was overheating.

Again, this is the front of the CAC (toward front of coach).

 

 

image.png.99c2c5f9a0bd5d0d14c31d1be0ad7570.png

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Ya, and consider intake manifold temperatures!  That is what the CAC is for-- to return very hot post-turbo intake air to close to ambient temperature.

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Brett, your picture of a dirty radiator is much better then the one I have on file, 

Damaged and dirty an not as well framed.

Rich.

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I think that I will stick to my two side radiators setup with those two huge squirrel cage fans to cool my turbo air. LOL!B)

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Great photos guys!! 

I clean ours annually on my winter portion of maintenance before I put it away for the season. Garden sprayer and Simple Green Extreme Motorsports. Monaco left me two access holes between the stack to get up in there and soak it down. I have a side radiator so its not so bad, but I still get some crud that is drawn in from Campgrounds without paved roads. Our coach has an aggressive fan drive hydraulic system (pre computer and wax valve design)

RV's require a lot of routine maintenance to keep them on the road (not to be confused with road side :P) this is just one more piece of the puzzle, along with checking electrical connections that is probably not published in any manual and no shop will perform it without asking, and I'd bet that most will just blow compressed air in and call it a day :o

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Great picture of a clogged CAC. 

Jim S, That is anouther of my pet peeves is the lack of instrumentation. I wonder what his EGT's were running with that mess. 

Bill 

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28 minutes ago, WILDEBILL308 said:

Great picture of a clogged CAC. 

Jim S, That is anouther of my pet peeves is the lack of instrumentation. I wonder what his EGT's were running with that mess. 

Bill 

I don't have a clue, Bill, but I assure you it was too high.

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