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I have a 2001 American Eagle 40 foot with a Cummins 350 that weights 33k.  I tow a Grand Cherokee that weighs 8k.  I am told that I need and estimated 10 horse for every 10k of weight so I am somewhat under powered.  I have had my radiator fins pressure cleaned, the cooling system flushed and pressure tested and the fans tested to make sure they are kicking on and running at the appropriate time/temp.  Additionally I have changed out the thermostat to make sure it is not sticking or causing flow issues.  On hill climbs in Colorado, Arizona and Nevada I will constantly overheat and have to pull over to cool.  I use the Alison mode to run between 2200 and 2400rpm during climbs to increase circulation but eventually my alarm kicks off.  I never heat to critical levels but alarms start at about 190 or 200, normal running temp for this coach is 160-170.  My temp gauge goes up to 240 but I never heat more than 200-210 but I don't like running that hot and the alarm is distracting.   Besides the climbs, I saw last week this heating on flats in Nevada.  Of course the outside temp was 100 but I would not have expected overheating on flats.  Now in the fall and winter months most climbs and all flats don't cause overheating due to the cooler air.  The engine is well kept, has about 75k on it and fluid and filters are constantly maintained.

Now what is very strange is that I lose about 1/3 gallon of coolant every 400-500 miles.  It does not drip out as I have zero leaks under the coach.  It is not making it's way into the engine as engine fluids show absolutely no signs of moisture.  I have had the system pressure tested 3 times to make sure I don't have a high temp hiss/steam leak and the reservoir tubes and cap are not leaking.

My questions are as follows.

1. Does this just sound like a HP issue and that the 350 just can't handle the 41k pounds of coach and toad?

2. Any ideas where the coolant may be going?  Some have suggested it may be leaking into the turbo but that makes no sense to me

3. Does anyone know of an after market turbo monitor gauge so I can monitor that with RPM?

4. Are there any after market cooling systems that can be put on to help with the overheating or do I just need to buy a new coach with a larger engine?

Thanks for reading!

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wood6406,

Welcome to the FMCA Forum.

Not a HP issue.  No, you won't be the first to the top of hill, but you should be able to drive it such that it does not/rarely overheats to the point of alarm.

Choose a gear and throttle such that you still have a little throttle left (flooring it will still increase speed).  You are in the correct RPM range.

Assume this is a side radiator/CAC.  If so, you also need to check that the fan is cycling to HIGH as temperature rises above thermostatically controlled temp.

160-170 sounds on the cold side for a 2001 ISC.  About the only other maintenance I would do is replace the thermostat with a Cummins speced for  your engine serial number.  A thermostat can hang up/only partially open.

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Sometime I believe we over think the RPM/engine temp/trans temp/gear, etc, issue. During our recent 3,500 mile trip out west, with several runs over the Continental Divide, I never touched the Allison....I just let it do it's thing.  As the engine got hot, it down shifted as required and automatically turned the fan on.  The down shifting kept the torque/HP where they needed to be for maximum efficiency.

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Really depends on power to weight, design specs of cooling system, condition of cooling system, etc.

Overheating on a DP is not that uncommon, particularly in 100 degree F temperatures on long grades.

Knowing how  to identify when your coach is likely to overheat and "driving around it" is something that all DP owners should have thought out ahead of time. "Plan B" is part of the heavy vehicle experience.

Yes, we have climbed the Tehacahapi/Bakersfield grade in July early afternoon (driving from Flagstaff).  No overheating in rear radiator DP.  Just selected a gear/speed/throttle that worked and "toddled up the hill". Others passed us, but over half were on the side of the road before the crest.

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There's a reason they have the climbing lanes on the long grades. There's also a reason you'll see truckers in the right lane going slowly with their hazard blinkers on when the grades get steep. We have to do it in our coach from time to time. It's just part of the fun. Just pull to the right lane and keep downshifting until, as Brett said earlier, you have a little throttle left to spare, even if it means going 30 mph up the steepest grades.

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Wood

How long have you had the coach? Is this a new problem or one that is getting worse even with the cleaning and replacing of parts? Brett is right, this has nothing to do with the weight or hp and that the usual  suspects are the fins and the fan. I am with Brett, 167-170 sounds a little cool. Is that the rating on the t-stats? What was the order of the cleaning and changing of the parts? Has there been any noticeable change after each repair assuming they were not completed at the same time? If everything else is good, I may lean towards the radiator needing to be cleaned internally or replaced. 

As far as the loss of coolant, it may be going past the cap at high temp but that should fill the overflow tank. When you pull over to let it cool down, is that tank full or empty? On mine if I fill the tank to the cold level, when it is cold, I will continually add coolant, but if I just keep a couple of inches of coolant in the tank I will never have to add any. 

Good luck and keep us informed.

Gary

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Thanks to Brett, teaching my Linda, how to use the gears and RPM's correctly, she has no problems going up long, steep grades, or going down!  She has a 40 foot, Phaeton 2006, DP 350 CAT. With a 2014 Expedition Toad, Weight's more than a GC.

Richard.  Never had a coach that used Truck lane on grades.  In 36 years, and 5 coaches neither has Linda! 

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1 hour ago, manholt said:

Richard.  Never had a coach that used Truck lane on grades.  In 36 years, and 5 coaches neither has Linda! 

Then you've never experienced the joy of an 8V71.

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Welcome to the forum. 

9 hours ago, wood6406 said:

I have had my radiator fins pressure cleaned, the cooling system flushed and pressure tested and the fans tested to make sure they are kicking on and running at the appropriate time/temp.  Additionally I have changed out the thermostat to make sure it is not sticking or causing flow issues. 

That sounds good. Did you check that the Charge air cooler is clean and no gunk between it and the radiator? If the person doing the pressure cleaning doesn't understand this he may not have gotten it clean. 

 

9 hours ago, wood6406 said:

I use the Alison mode to run between 2200 and 2400rpm during climbs to increase circulation but eventually my alarm kicks off.  I never heat to critical levels but alarms start at about 190 or 200, normal running temp for this coach is 160-170.  My temp gauge goes up to 240 but I never heat more than 200-210 but I don't like running that hot and the alarm is distracting.   Besides the climbs, I saw last week this heating on flats in Nevada. 

What are you calling "the Alison mode"?  Are you down shifting using the shift pad? 

I agree with Breitt that temp seems low. I would do as he suggested. One thing I have found is the flats in Nevada are seldom flat. I was running along in cruise not watching my gauges to close and all of a sudden my hi temp warning started going off. Got to looking and even though it hadn't down shifted it was running full throttle and max boost to hold the speed. It was also driving my EGT way higher than I like to see. I slowed and manuel down shifted to 4th and let it cool down. 

9 hours ago, wood6406 said:

Any ideas where the coolant may be going?  Some have suggested it may be leaking into the turbo but that makes no sense to me

With out hands on a likely scenario is it is getting blown out of the expansion tank. I believe yours is set up similar to mine. The tank is not an overflow tank it is part of the radiator system. That is it is under the same preshure as the radiator. I bet you have a long hose where the vent is on the neck where the cap is. This hose routes down to below the bottom of the coach. It could be venting out when you have higher temps and preshure and it would be hard to see. 

 

9 hours ago, wood6406 said:

Does anyone know of an after market turbo monitor gauge so I can monitor that with RPM?

You might look at Silverleaf or Scangauge.

http://www.silverleafelectronics.com/?q=node/6

 https://www.scangauge.com/products/scangauge-d/

The only problem is I don't know if they show Boost or EGT temps. There are numerus places to buy the gages.

Bill

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7 hours ago, manholt said:

My coach came with Silverleaf.  I can scroll it up & see it on my camera screen.  

That is true some "fancy" coaches already have Silverleaf. Does it show turbo boost and EGT?

Bill

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When I entered the industry in 1965, an 8V71 was a hot item.  Nothing wrong with using the truck lanes. The hard pull west of Needles California  has a truck lane. When  the outside temp is over 110 it is used by all manner of vehicles. Motorhomes included.

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