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baileysmom

340 Cummins Overheating and Slowing Down

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Hello Everyone,

I'm new here and thought I would try to get some guidance on a problem we seem to be having.

We have 2011 Coachmen Crosscountry with a 340hp Cummins and a 2500 Allison.

We now have 16K miles on it and have enjoyed it tremendously.

We recently went full time and after a few months of travel began to think we might be over weight.

So we shipped things back home and traded our toad for a lighter one and then this week we found a whole new set of problems.

Driving along I-10 westbound from San Antonio to Fort Stockton we started slowing down tremendously from about 65 to 40 mph when going up hills.

I understand things get a little slower on steep grades but this was even on long slow inclines.

And if we didn't watch it carefully and let the cruise control take us up and over the hill, we would overheat.

The temp would go from the normal 194 to 201, 201, 203, 204 and then the stop engine light would come on.

We would simply take the cruise control off and let it slow down and the temp would start dropping back down.

Now we recently had all the fluids and filters changes in San Antonio before making this trip so its not a fuel filter.

We have done a lot of research on the forums and we now know we'll need to get it into a shop as soon as we can to really tell what the problem is....but we were just wondering if anyone had an idea of what it could be......thermostat? or something more serious?

We appreciate your help and your time with your responses!!!

Take care!!!

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Welcome to the FMCA forum! I have the same 340hp Cummins and a 2500 Allison in my Bounder. My electronic fan clutch was bad. It is an all too often problem for the Freightliner installed fan clutch. I was able to get Freightliner pay for the part and I paid for the labor. As for dropping from 65 to 40 on hills, I think if the hill is steep enough, that will happen. You can try lowering your gear to raise the rpm which will keep it cooler and may help maintain you speed a bit but you will still lose speed on hills.

Good luck and I'm sure there will be many more comments.

And get your coach weighed on each wheel position to make sure your not over weight and you can balance your load.

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Yes, welcome to the FMCA Forum.

With a 5 year old rear radiator DP, when was the last time the CAC (Charge Air Cooler) and radiator cleaned? Other than a failed fan clutch, this is the #1 reason for overheating of a rear radiator coach.

Suggestion: access the front of the CAC (from bedroom or closet). Look inside the fan shroud with a strong flashlight (yes, easier at night). Verify that the perimeter, particularly the lower perimeter is as clean as the center of the CAC (the fan blades "sling" dirt to the perimeter).

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Hi Brett,

I have never had the CAC or radiator cleaned.

Unfortunately, until lately the MH sat in my driveway. I took a few short trips with it but never had a problem with it.

We left Kentucky the fist of February. Went to Myrtle Beach, Savanah, Mobile, Baton Rouge, Houston and in between Houston and San Antonio it started slowing down.

HAHAHA now here's the best part!!! I thought we were over weight.....so I shipped back 500 pounds of STUFF.....traded the pickup for a small car and dropped our overall weight by 2500 pounds. Got all the fluids and filters changed and thought that would be it.

WELL, on the way west out of San Antonio we his some small hills and some really nice steep hills. We could barely get up the hills. At one point we slowed to 35 mph. I just let the cruise control drive it and sat back in the right lane and let everyone go by staring at us.

So, now we're sitting in Alpine, Texas trying to figure out what to do next. Obviously we need to go to a Freightliner or Cummins shop somewhere soon. There isn't anything in Alpine so I suppose we'll work our way to Odessa and try to get it checked there.

I hope its just a cleaning job or a fan clutch and nothing serious!!!

I will wait till it gets dark here in a little while and check the engine through the hatch in the bedroom. I will let ya know what I find.

Thanks for your help and guidance!!!!!

Take Care!!!!

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One other thing is when you hit a hill and start slowing down, manually down shift in to 5 or 4th. Keep your rpm up around 2000 rpm this will help keep it cooler.

Let us know what you find out on the CAC.

Bill

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Hey Guys,

Well, I did as you suggested and opened the hatch in the bedroom to check the CAC. Well, its too far back to even see the fan. I'm not a mechanic but I have no idea why its there. I'm sure someone knows.

However, I did open a rear side panel door near the engine and climbed in there as far as I could go to get a look at the fan and the shroud surrounding it. The fan looked ok not very much dirt. The housing looked a little dirty all around the outside of it but I couldn't tell how dirty really....and I was using a very strong flashlight.

HOWEVER, I did notice what looked like fresh scraping or scratched on the fan housing where it appears the blades were/are making contact with the housing.

IS THIS NORMAL?

Other than that I can't really see very well in there.

What are your thoughts?

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Yes, absolutely clean the front of the CAC.

And, with performance issues on any diesel, the absolute first thing to do is change the fuel filter(s). Said another way, make sure ALL filters are new. You may have three including the strainer on the chassis rail. Freightliner can give you full information when you call them with your VIN. The reason: If fuel flow is restricted because of a clogged filter(s), it will absolutely first show up when the engine demands maximum fuel flow.

Could it be something else-- sure. But fuel filters are a very inexpensive first step!

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baileysmom, double check your receipt from the maintenance just performed, see how many fuel filters were replaced, call Freightliner like Brett mentioned and double check to make sure they replaced all of them and not just them ones they saw or that were convenient to access. I would also see what brand of filters and part numbers that were installed, make sure they are the correct spec for your application, Freightliner or Cummins can tell you that. I have seem to many shops run with the approach "if it screws on it must be correct".

I would strongly recommend having the coolant package (Radiator, Cold Air Charge cooler, transmission cooler) in the rear cleaned as part of annual maintenance.

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Correct-- this is NOT normal. Check for play in the fan bearings (particularly if they have not been greased)! If the bearings are bad, do NOT drive it. If the bearings completely fail, the fan could be thrown through the CAC!

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Hey guys,

I just climbed up in there again with a better flashlight. The fan blades do not move or wiggle. They will turn if I turn them and they do not appear as if they are scraping the sides of the housing......whew!!!

Now for the good part!!! I used a much better flashlight!! I can see how dirty it is now!!!!! The RV park we are in has an RV Wash Area. I am going to find some simple green and a wash wand and "getter-done".

In addition, I am going to call the Freightliner place up in Odessa and try to make an appointment to take it in to have it checked.....just in case!!!!

You guys have been great help!!!!!

I truly appreciate your time!

Take Care!!

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baileysmom,

Buy Simple Green Extreme!! It is made to clean aluminium and the Radiator and CAC are made from aluminium.

I have found the 32oz. sized spray bottles at Pep Boy's.

The gallon size is often a special order item . Need to mix 1 part extreme to 3 parts water to clean grease off engine and radiator.

The Extreme version is FAA approved so an aircraft service center might stock the Gallon size.

The bottom left corner - looking from the engine side of the fan is the hardest area to get clean because of the pitch angle of the fan blade.

Please WEAR EYE PROTECTION when working the the cleaner !!!!!!

Rich.

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Here's an update......

 

Well we washed the radiator with some simple green and left Alpine for Odessa where we were going to a Freightliner shop to have it checked out.

The washing made a tremendous improvement on the performance of the engine however, it was still running hot. 

The next day we took it to the Freightliner shop who apparently forgot we were coming.  After sitting around a couple hours, they told us they would not be able to get to us that day and then told us they really don't work on RV's much and are more or a BIG TRUCK shop than anything.  I quickly bowed out very nicely and left.  We drove about a block away to a Cummins Shop.  We only waited about an hour when they took us in and hooked us up to a computer to run the codes.  After some checking, they found the culprit. 

It was a CAC hose clamp!!!! yep that right!! some kind of hose running in or from the CAC caused the exhaust system to overheat.  The clamp was about six inches in diameter and was spring loaded.  The clamp had broken and become disconnected. 

They replaced it and ran more tests to make sure that was all that was wrong with it.  They even took us out on the highway for a test run.

These people were some of the most professional and friendly people ive come into contact with for some time. 

Well, the clamp cost $15.10....labor was $448.20.   We joined the Cummins Power Club right on the spot, which cost $19.95 a year.  That membership gave us a discount so the final cost was $418.64.

We have learned quite a lot from this experience and we want to thank all of you for your input and help along the way.  You guys are great!!!!

Thanks again!!!

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Thanks for the update.

I am surprised that performance had not also suffered with loss of boost due to bad hose clamp (air leak on intake side) at the CAC.

Also, you mentioned cleaning the radiator.  Did you also clean the "cooling package" from the FRONT? The CAC is the "first thing in line" in the cooling package so, that is where the vast majority of the dirt will be deposited.  It can only be cleaned from the FRONT-- access under bed or closed.

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Yes, thanks for the update.

If I could make a driving suggestion.  When you see a fairly good climb ahead, take it off of cruise control after pressing down on the accelerator pedal and reaching the same as cruising speed.  From that point on do not move your foot, keep it in the same spot.  As you climb the grade the engine and transmission will maintain a proper climbing speed and your chances of overheating will diminish considerably.  As stated, if the engine temperature starts to climb, drop it down a gear and maintain 2000-2500 rpm and you should see a drop in engine temperature.  Leaving the cruise control on when climbing steep grades will cause a WOT (Wide Open Throttle) in most cases and the engine temperature will rise.

Just my experience and humble opinion. It does work for me and I have the same engine and transmission as you do.

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One the things that I feel is very important is to monitor your boost pressure.  When an air leak occurs in the CAC system the boost will not reach "normal" values due to the leak and the engine will run hotter under nearly all conditions but especially when there is demand for boost under load.  

Having had instances similar to Baileysmom where a small hole had been made in the CAC due to gravel being picked up by the fan.   Also had the dirty CAC issue.  One thing I decided to do was to install a Silverleaf VMSpc monitoring system.  This is a module that plugs into the data buss and interfaces with the free software available from Silverleaf and installed on your computer.  Most of us carry a laptop when traveling and with this device you can arrange to monitor any/all of the parameters available on the data buss in far more detail than is present on gauges.

 Creating a baseline of your parameters and recording data and then monitoring any changes over time  will provide lot's of info if difficulties show up.  After having put 150K miles on a 2001 Bounder with a Cummins ISB over a period of 15 years, I have been able to see issues starting to arise and take preventive action and if not able to prevent I have a good idea where problems exist.  More detail data is available on my 2005 American Tradition with TripTek but still gonna have the VMSpc along so that I can more detail and info on parameters that are not visible on guages or TripTek.   

Bob in TX

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I won't drive without good EGT and Boost gages. 

Back to the question of overheating on hills. I know there are people who think the transmission will downshift to the right gear all the time every time. Sometimes yes sometimes no. When climbing a hill the most common cause of  overheating occurs when you are running the engine at WOT at or below peak torque and you can't accelerate under these conditions. This is what the old timers call "lugging the engine" You should downshift till you can accelerate in the selected gear. Then maintain your rpm above peak torque and below max rpm (the goal is near peak HP) till you finish the climb or you can up shift and accelerate in that gear. Doing this will reduce EGT temperatures and  load on the engine and will improve cooling.

You don't have to be on a steep (obvious) mountain climb to have overheating problems. When I first got my coach I was west of the Grand Canyon headed to Las Vegas and hit a long slow elevation increase. I was running cruise at the time and the slope was so gradual you didn't notice it. Well I started to get overtemp warnings. I did a quick scan of the gages and found the computer had me running at max boost trying to maintain road speed on that incline. I dropped  to 5th and temps started to come down. 

Bill 

  

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Bill, you have brought up a good point...EGT gauge. I do not have one on this coach and I have often thought about installing one, mostly in part so I know when its safe to shut it down. Since my engine is not altered or performance modified MY EGT's really shouldn't be a concern while driving but shutting it down when its too hot is a concern. I usually let it idle when I go into a CG to register, then a slight tip of the throttle to crawl to the site I was never concerned I was shutting it down too fast. Even after I pull into a site I will feather the brake pedal so the compressor kicks in and allow it to purge before shutting it down. I have just been a custom to having one and without it is a little concerning.

Is there a gauge with an electronic sensor rather than the typical sealed copper tube design?

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1 hour ago, jleamont said:

Bill, you have brought up a good point...EGT gauge. I do not have one on this coach and I have often thought about installing one, mostly in part so I know when its safe to shut it down. Since my engine is not altered or performance modified MY EGT's really shouldn't be a concern while driving but shutting it down when its too hot is a concern. I usually let it idle when I go into a CG to register, then a slight tip of the throttle to crawl to the site I was never concerned I was shutting it down too fast. Even after I pull into a site I will feather the brake pedal so the compressor kicks in and allow it to purge before shutting it down. I have just been a custom to having one and without it is a little concerning.

Is there a gauge with an electronic sensor rather than the typical sealed copper tube design?

I have had a couple of people tell me that a stock engine won't run high EGR temps but my actual observation is that it will. I have a 2003 5.9 and it is computer controlled. I have not been able to test one of the mechanical engins,(they may not run high egt) but I wouldn't do any mods to one without having gages.  

I installed the egt probe from Banks,(it is electrical) I also have the IQ for display and the Economind Diesel tuner. They sell stand alone gauges but I didn't like them. 

Bill

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Some good points regarding monitoring system vitals.  I have a Mini Max tuner for the Dodge Ram which has a 6.7 Cummins.  I keep the setting on the HUD so I can watch EGTs.

On the coach I often toggle over on the information screen to monitor vitals vs. what I see on the dash gauges.  However, I don't have EGT for the coach.

From a West Texas Hill Country speed and overheating perspective: Some of those hills are merely slight inclines to a regular car or truck.  But, to our big coaches one cannot expect to climb all of them at regular cruising speed.  I monitor my RPMs and temperatures and if that means going slower......so be it.  Fuel consumption will be better if you do that.

So, watch the 18 wheelers.  There is a reason they are climbing those "hills" at 45 mph.

Blake

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On a computer controlled engine and transmission it would be hard to push it hard enough to run the EGT's up with an OEM tune. Mechanical engine I could see it more so than on a computer controlled, especially if it was a manual transmission. My old service truck was a 1996 Ford F350 7.3L Powerstroke with an ATS automatic behind it and 400hp 800lbft torque (Banks and Edge tuned over each other), Pulling my mobile PM trailer with a loaded service body truck my total combination was just shy of 20000 lbs, on a steep hill I couldn't over heat the turbo, the transmission would down shift rpms would go up and EGT's would drop. It had the Banks EGT gauge with the sensor in the down pipe right at the turbocharger. I am sure if it was a manual transmission and I was lugging it I could have achieved that, not with the automatic. The only time I have heard of a stock electronic engine with an automatic achieving this was with a defective VGT (variable vane) turbo.

I run a "Scan Gauge" in the coach now, but there is no sensor for EGT in my coach and I do not believe EGT is an option with that system. I would need a gauge with an electronic sensor to route all the way up front and mount it in the dash like it came with it. I would have no problem doing it if I could locate a gauge kit that was a close match to the factory VDO gauges.

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Figured it out. Auto meter makes a gauge #3344 with a required extension module #5257 (specifically for Marine or Diesel Pushers so the gauge remains accurate through all of that extended wire) so the probe gets inserted in the turbo outlet pipe, module gets mounted back in the engine bay area (10' lead on probe) then you run 18 gauge wire up to the dash and install your gauge. Total out the door just shy of $300.00. The gauge is very similar to my factory gauges, I had to ask for a chrome custom bezel so it matches the rest of them.

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Would somebody kindly explain what an EGT guage is and why we need one?  I have a Silverleaf Chassis Monitoring System on this coach, which gives me eng and trans temp digitally to one degree.  I have an aviation back ground where we had either an EGT gauge, PTIT gauge or TOT gauge on various turbine engines so I know what they do and why they are there.  So I'm not exactly sure what is critical on a turbo diesel that needs another gauge...in addition to the Silverleaf.  

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