Engine overheating-need help (warning long post)

[Jeep trekker]

I have owned this 2007 Camelot 42 PDQ for two years now and the engine overheats when climbing mountain passes. For example, climbing from Alamogordo NM to Cloudcroft NM which is about 15 miles of 6% grade, I have to pull over a couple of times to let the engine cool off. Once pulled over, the engine will cool off quickly so that I can continue. I follow all the recommended procedures such as reducing throttle, downshifting and keeping the RPMs over 2000.

I just thought it was the nature of the beast until recently when I started talking to other Camelot owners who didn't have the same issues. So I took it into Rocky Mountain Cummins in El Paso and asked them to check it out. They reported no fault codes and they inspected the cooling system and gave me a clean bill of health. Off I go on our 3 month trip.

Everything was fine until I got to the Rocky Mountains. Climbing Lookout Pass on I-90 in Montana the coach began to overheat, the check engine light came on (224 degrees)and, as I pulled off to the shoulder, the stop engine light came on (234 degrees on the Aladdin Jr.). Let it cool off, then went on. The Check Engine light came on again on 4th of July Pass. I should note that on flat ground it works fine (Columbia Gorge, 107 degrees outside and the engine runs in the high 180s)

I got to the Monaco International Pre-Ralley in Coos Bay and started asking questions. The Monaco maintenance people said that this shouldn't be happening as did the Cummins engineers. I asked about additional venting of the engine cover since I have noticed that more recent Camelots have more venting in the engine cover. They said that was unnecessary. Visiting with other Camelot owners, they reported no issues. I also was told that the cooling system for the side radiator Monaco's is a very efficient system with a two speed fan (more discussion on this later in this post).

When heading back eastward over the Cascades, I again had to pull over to cool off. I was following an identical coach except that it was a 2008. I talked to him later in the day and he reported that it got a little hot, almost to 215. I'm on the side of the road above 224.

I decided enough is enough so while visiting family in Sacramento I took it to Sacramento Truck Service and explained my issue. Initial inspection revealed that the fan was running even though the engine was cool and at idle. They suspected the Fan Control Module (Computer?) was faulty. The next day I got a call from them and they reported that they were showing no fault codes and that they had run the engine a full power on the dyno for over 15 minutes and it never got over 197. After discussing it they decided to look deeper. They then called back and said they downloaded the Maintenance Log (or something like that) and it had indeed overheated within the last 10 hours of operation. (the no fault codes thing puzzles me) They changed out the fan control module and I was on my way home.

Everything was fine until I got to Tehachapi pass where I had to pull over twice. I also almost had to pull over climbing up the hill coming east out of Quartzsite Az though it was a hot day.

I am home now and want to resolve this issue. My first question is does it really have a two speed fan and, if so, how do you check to see if it is going into high speed. I am sure there are some crack diesel mechanics in the El Paso, Albuquerque, Phoenix or Tucson area but I don't know who they are. Any recommendations? Any other suggestions of things to check? Why no fault codes? This is very frustrating for me, to the point that I am wondering if a trade is in order. That is a shame because I otherwise really like this coach.

Thanks for reading and any ideas are appreciated.

[Spinner]

Malfunctioning thermostat? Plugged coolant filter?

[nodine]

Richard,

Just a thought, but maybe the coach is not actually overheating and there is a problem with a sensor. The Cummins may have its own temperature sensor signaling the ECM and that is always within operating temp, thus no codes from the ECM. The coach could have a temperature sensor installed by Monaco that provides temp information for the dash/Aladdin system. See if you can find a shop that can connect a diagnostic recorder to the coach and then find a long grade to climb hopefully setting off the over temp alarm. Compare the diagnostic reading to the dash reading and see if they agree.

Bob

[super_rep]

Have you cleaned the radiator fins? They collect a lot of dirt, especially the rear radiator coaches. Buy some coil cleaner at HD or Lowes and be sure to flush the fins in the reverse direction of the air flow. This solved an overheating problem we had about 5 years ago.

[William Willard]

Jeep trekker -- We have the same coach, & have had it since new -- It now has over 70,000 miles on it & I' ve never see the temp over 205 -- I live in AZ , so been in some HOT & long climbs -- However, I never climbed a mountain @ 2000 rpm's -- When I start losing rpm's , I manually downshift, & keep the rpm's around 1600 -- With the side radiator, the fan controller is what controls the fan speed, not engine rpm's -- Are you using the cruise control to climb mountains ? Change the thermostat -- It' s a easy DIY project -- You can get one on eBay -- Bill Willard

[YC1]

Easy fix. Change the thermostat. They changed the design of it at some point so the new one will look different. Had heating problems the last time I went over the Grape Vine. Had been over it a couple of times before and over much worse hills and never had a heating issue. I would be a bit miffed if the shop had not changed it just for preventative maintenance. It is a $50 part. Take the old one out and put it in boiling water next to the new one. Watch how fast they open and how far they open,.

Ditto on cleaning the coils of the radiator. Buy a can or two of "coil cleaner"/ "condenser cleaner", at Home Depot or Lowes. Yellow cap. It is very good at cleaning them and you can use it to clean your AC's too.

[William Willard]

Jeep trekker -- The Cummins part # for the trermostat is. 4936026 -- I didn't find any on eBay, but just google the number & you will find them -- Cummins has them as obsolete, & uses a much different thermostat, & a lot higher price -- There is a hanger in front of the engine to remove engine -- 2 or 3 bolts holds it on -- Remove that hanger, & the thermostat housing is right there -- 2 bolts hold it on -- Remove those 2 bolts & remove the thermostat -- But first, drain enough coolant to empty the surge tank -- You will still lose a small amount of coolant when you take the housing loose -- You may have to cut the connecting hose, but need to replace it anyway -- It's only about 5 inches long -- The thermostat uses no gasket, so don't worry about that --- The bolts torque at 18 foot lbs, but double check that -- There should be a fuse holder coming off the hot side of the chassis battery --- With the engine running, pull that fuse -- If your fan goes to high, then your controller is OK -- The coolant fan defaults to high when it looses power --

[Jeep trekker]

Thanks to all that replied.

A cleaning of the fins is in order. I'll need to find a place, like a loading dock, that I can put the RV such that I can get under it to spray from the inside out. This thing sits so low, i can't get under it. (The Rocky Mountain Cummins mechanic said the fins were clean, but then, he said there was nothing wrong)

I will also change the thermostat out. Thanks Bill for the detailed description of how to do it and to YCI for the insight about the new version.

Nodine; I had that same discussion with the folks at Sacramento Truck Center. My understanding is that there is a Monaco sensor that goes to the dash gauge and that the Aladdin gets its info from the ECM. Both are reading hot. Also, doesn't the ECM send the Check Engine and Stop Engine signals? If this is not the case, let me know.

Spinner; It is my understanding that the Camelots didn't get a coolant filter until 2008. I can't find any reference to one in my manual.

Bill, you answered some of my questions on the two speed fan system. One of the reasons I was keeping the RPM over 2000 was the belief that it was necessary to keep the fan speed up. Since this is not the case, I will rethink how I operate the vehicle during climbs. I was also aware that the fan defaults to high speed if the controller is bad. So the controller sends a signal (or lack of signal) to some mechanical valve for off, low and high. (I guess with no signal it defaults to high?). My question is, is it possible that this valve is stuck in the low position? Where is this valve and how can you test it? If I pull the fuse, how do I know if it is indeed running high and not low? Someone in Coos Bay mentioned using a strobe to determine the fan speed. This is well above my mechanical knowledge level.

But first things first. I'll clean the radiator fins and change out the thermostat. We'll see if that does the trick. It will be a few weeks before I can get to that but I will report on the results.

Thanks again to all the replied and if anyone has some other thoughts, I am all ears.

[YC1]

5284903 is the new part number. It does not look like the old one. It is about three times as tall but it fits.

Shop WEB Coil Cleaner at Lowes.com

The coil cleaner is amazing. If you spray it from the outside with the rear higher than the front it will penetrate forward. Let it soak for several minutes. Use low pressure to wash it forward. This stuff is great on any coils such as the AC's.

[JeepTJ5]

I sure will be interested to see if the thermostat replacement works. While I don't think I have the same engine (Mine's an ISB-300) I have generally the same problem. It didn't start until after Rocky Mountian Cummins (In Reno) changed my turbo. By the time I figured out I had a problem, I was long gone from Reno, so no recourse. (of course) I'm not a fan of Rocky Mountian Cummins. They tried real hard to not cover the warranty replacement, and only relented when the Cummins Rep convinced them it was indeed a warranty job. I won't say they out and out lied, but close.

[Gorlininc]

I see you down shift and keep your rpm above 2000 RPM. I was just in the Rockys and I have a similar issue with my 330 ISB cummins. I cleaned the radiator. What I figured out was I wasn't downshifting to the lowest gear. I'll run 4th gear at 48 MPH. if my temp goes above 200, I slow to 35 and 3rd gear. If the temp goes above 200 I slow to 25 MPH and climb in 2nd gear. The temp settles at 197 on those climbs.
I bought a scan gauge which reads the cummins sensors temperatures and RPM rather than the diplomat gauges.

Rick

[Steve Sh]

Which scan gauge and where did you purchase it?

Thanks,
Steve

[William Willard]

Jeep trekker -- The controller is about a 5x5 aluminum colored box , with some small hydraulic lines & an electrical wire going to it --- It's located above the air filter , & to the left of the surge tank -- It's behind some metal framing -- There's nothing you can adjust or fix , so no need trying to screw with it -- However, there is an electrical connector going to it that you should disconnect & spray some cleaner in it -- You will know when the fan is on high , because it will sound like a jet taking off -- If you can find the thermostat that I suggested , I would use that -- The only reason Cummins changed , was because a few of the older version had a bail break -- Most of the one's who's responded to your post have a rear radiator coach -- With a coach like that, higher rpm's would be the way to go , but a side radiator, such as our's is a different beast -- I never get in a hurry going up or going down -- Rear radiator coaches does have a problem with dirty radiator fins, but not so much with the side radiators -- Before changing thermostats, you will need to get a piece of 2 I/4 inch coolant hose, about 6 inches long -- That 's the connector hose going to the thermostat housing -- Have you changed the coolant ? Now would be a good time to do that --- After all, it's only money -- Bill Willard

[Gorlininc]

It's the scan gauge D (diesel)
On Amazon.