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Old 05-17-2006, 12:38 PM   #1
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I made this post on rv.net, but thought I'd also cross post it here. I'd appreciate any insight the group has.
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We have put about 10,000 miles on our coach in all kinds of terrain and I have never seen the engine temperature climb off the 200 degree mark.

The situation:
Cummins ISL, side radiator, Freightliner chassis. As far as I know, there have never been any recalls by Freightliner on my specific chassis for anything. (This chassis as built up by Thor in their Mandlay did have a recall for fan/cooling issues and some Allegro Buses had some cooling problems several months ago)

Today in the Black Hills our engine temp got up to 222 degrees while climbing a long and fairly steep grade on Hwy 16 out of Rapid City on our way to Keystone, SD.

The ambient air temperature was about 80 degrees, our coach was almost at gross weight (31,400 with 32,000 max) and we were pulling a Jeep that weighed 4,840. Coincidentally we just weighed the coach since I'm trying to offload the front axle a little.

I had the Allison mode selector in the 'economy' position like I always do. We started up the hill at a fairly low speed - perhaps about 45 or 50 mph. Our RPMs were staying in the 1500s range during the hill climb until I intervened.

Once I noticed the temperature at alarm stage I downshifted the transmission to 4th gear to get the RPMs up to 2,000. The temperature did respond by coming down to a little over 200. Every grade after that I had to downshift to 4th gear to manage the temperature. Finally I took the mode switch off the economy setting so we would kick down into a lower gear quicker and have the RPMs come up much more than the 'economy' mode.

Do I have a fan problem, some other kind of problem, or is this normal performance??
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Old 05-17-2006, 12:38 PM   #2
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I made this post on rv.net, but thought I'd also cross post it here. I'd appreciate any insight the group has.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We have put about 10,000 miles on our coach in all kinds of terrain and I have never seen the engine temperature climb off the 200 degree mark.

The situation:
Cummins ISL, side radiator, Freightliner chassis. As far as I know, there have never been any recalls by Freightliner on my specific chassis for anything. (This chassis as built up by Thor in their Mandlay did have a recall for fan/cooling issues and some Allegro Buses had some cooling problems several months ago)

Today in the Black Hills our engine temp got up to 222 degrees while climbing a long and fairly steep grade on Hwy 16 out of Rapid City on our way to Keystone, SD.

The ambient air temperature was about 80 degrees, our coach was almost at gross weight (31,400 with 32,000 max) and we were pulling a Jeep that weighed 4,840. Coincidentally we just weighed the coach since I'm trying to offload the front axle a little.

I had the Allison mode selector in the 'economy' position like I always do. We started up the hill at a fairly low speed - perhaps about 45 or 50 mph. Our RPMs were staying in the 1500s range during the hill climb until I intervened.

Once I noticed the temperature at alarm stage I downshifted the transmission to 4th gear to get the RPMs up to 2,000. The temperature did respond by coming down to a little over 200. Every grade after that I had to downshift to 4th gear to manage the temperature. Finally I took the mode switch off the economy setting so we would kick down into a lower gear quicker and have the RPMs come up much more than the 'economy' mode.

Do I have a fan problem, some other kind of problem, or is this normal performance??
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Old 05-17-2006, 01:40 PM   #3
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John,

I believe this is normal. I have had same experience with my 400 ISL. Today, while traveling on I-80 in Nevada we were climbing a long hill with the ambient temp around 80 degrees. I noticed the engine temp start to climb so I manually downshifted to 5 and then to 4 taking the rpm to approaching 2000. It cooled back to normal and I continued the climb. Upon reaching the summit I shifted back to 6.

The first time this happened to me with similar conditions in Utah it caught me by surprise. Now, I keep an eye on temp guage whenever we start climbing the larger mountains.
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Old 05-17-2006, 02:32 PM   #4
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John,

This was discussed over on RV.net a month or 2 ago. LK23 has to do the same thing I do with my CAT C7- 350 at 30,000 lbs pulling the Mini at 2500 lbs. I watch the tranny and engine temp closely on a long climb. When the engine gets up to around 200, I down shift manually and get the RPM's up around 2000 to 2100. This cools things down.

I cannot speak for your engine but that is how I manage the engine temp on long climbs.

I do not leave the Econo mode set on the tranny so it is easier to do the manual shifts.
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Old 05-17-2006, 02:42 PM   #5
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I had a similar experience this weekend comming out of Needles, Ca. 95 degress , A long 10 mile grade fully loaded and by the time I got to the peak it was at 218 but came down right away, I could have lowered it by reving up in lower gear but I heard that 220 or less for short periods is ok. When I first got the coach it overheated real bad in any heat so I took it to a freightliner dealer and they adjusted the hertz on the fan clutch or whatever and now only on extreme grades with high external temps does it go up high. When I did overheat it before it blew a lot of the fluid out so make sure to check the level witch is not easy to do with the plastic resevor they built the coach with.
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Old 05-17-2006, 03:33 PM   #6
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when i was asking questions after we bought our journey, one ? i asked was about hill climbing,book says 1500rpms max torque is best but forum members said raise rpms 2000-2100 if temp starts to rise
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Old 05-17-2006, 04:20 PM   #7
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John my 400isl in a vestra pulling a suburban (5300) last summer in arizona long grade outside temp was in 90s, hot engine alarm and engine defueled. dropped trany to 4th gear and
the engine cooled down. Note I ras running cab
air, was later told under described conditions, run house air, and not cab air, tip from long haul truck driver, ok since then
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Old 05-17-2006, 04:53 PM   #8
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Thanks everybody for the responses. It appears that things are nominal for the situation.

What I think I ought to do is to spray some Simple Green on the radiator and rinse it off with water. We drove through quite a bit of dust today and a week ago coming and going to the last campground.

If the air temp is really warm, I'll bite the bullet and run the genny for the house AC instead of the dash air.

We'll see how it goes in a few days when we leave this area.
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Old 05-17-2006, 05:44 PM   #9
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I always spin my ISL in the 1900 to 2100 rpm range when going up long grades. Have not had a problem. I have done that with every rv or truck (different rpms for each one)that I have owned and did not run the temp up outside of "normal" range on any of them. So, in my opinion, you handled it just right.

For what it is worth, the chief mechanic at my rv dealership says to not run your tranny in economy mode when pulling hard. He claims that they have fewer complaints of over-heating from people that leave the trans in regular shift mode. I do not know if any of that is true, but I leave mine in "regular" mode all the time and have not had a problem with engine temperatures.
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Old 05-18-2006, 02:55 AM   #10
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Hi John (and others),

To echo (and clarify) what some of the others have suggested, the "mode" button doesn't really have any appreciable effect in most driving situations you are likely to encounter.

The possible exception being the exact issue you are experiencing.

If I understand correctly, the "Mode" simply causes the transmission to up shift earlier, in theroy increasing fuel economy.

This might be better regulated with your right foot, and your ears/eyes!

Most diesel engines don't respond like gas engines do in terms of how much fuel is being fed to the engine relative to the position of your foot on the accelerator. With diesel engines, the amount of fuel being fed to the engine has more correlation to the amount of "work" the engine is doing at a given rpm range. If you monitor the "engine load" display of your VMS (or equivalent) this explains why the engine load can be at 100%, despite the fact that you have only of the accelerator depressed. As the engine RPM's increase, the fuel being fed to the engine is decreased based on the accelerator position.

This is a long way of suggesting that the "mode" is more gimmick than anything else, at least for motorhomes operated primarily on the highway. Once you reach cruising speed, it has absolutely no impact at all. The only possible impact it might have would be delaying a downshift, and we see what effect that has (overheating). Having had many years operating large fleets of vehicles with Allison automatics, and trying every trick we could find to boost mileage, we came to the conclusion that the mode button is useless in vehicles like ours. If you read about other types of programming that the mode button can be used for, it makes more sense. Some applications (or vocations as Allison calls them) limit transmission shifting to certain ranges (say only gears 2-4) to reduce "hunting" for vehicles that drive in slow or stop and go driving, or that require frequent engine assisted deceleration. These are primarily in other "families" of Allison transmissions; however the touchpad controller is used more universally, hence the "less than useful" mode button. Some people I know suggest that the mode buttons real unspoken purpose in the MH series of transmission is to help reduce hunting, not to improve fuel mileage. Certainly, one could do a better job of controlling the shifting of the transmission with ones accelerator position, and most of us do just that once we have some experience.

As you might gather, we always leave the mode button off, and manually shift whenever engine load and conditions dictate. As it has been suggested, higher RPM's bring more cool air into the engine, move coolant, oil and transmission oil faster, and reduce internal stress. The cooling fan, being hydraulic, operates at whatever speed the controller dictates, mostly regardless of engine RPM's.

Thanks for indulging my somewhat overly detailed op ed!
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Old 05-18-2006, 03:59 AM   #11
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I have an 04 Journey that had the same problem. Several friends have had the same problem. We found it to be a dirty radiator. A mechanic told me the radiator is four inches thick and collects dirt due to the thickness. I used Purple Power from the local parts store. Used a spray bottle and once applied let it sit for several minutes before pressure washing it. I was blown away with the grease and dirt that came out. Now it runs cool even in 90 + degree weather going up hills with a trailer or van behind it.
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Old 05-18-2006, 04:16 AM   #12
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<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rg:
I have an 04 Journey that had the same problem. Several friends have had the same problem. We found it to be a dirty radiator. A mechanic told me the radiator is four inches thick and collects dirt due to the thickness. I used Purple Power from the local parts store. Used a spray bottle and once applied let it sit for several minutes before pressure washing it. I was blown away with the grease and dirt that came out. Now it runs cool even in 90 + degree weather going up hills with a trailer or van behind it. </div></BLOCKQUOTE>

Indeed, in your chassis, this is a common problem due to the rear radiator configuration, and an oft misrouted engine crankcase vent tube. The oily vapors get caught in the rearward airflow, clinging to the radiator fins, and attracting dirt at a highly accelerated rate. The fouling that results from this condition reduces airflow across the fins, and results in diminished cooling ability.

Owners with the rear radiator configuration need to insure that it is regularly cleaned, as laid out in the maintenance guide.

Also, the mode issue and the downshifting practices remain the same across these chassis. Rear radiator chassis have a direct drive cooling fan, generally without a fan clutch. Increasing engine RPS's during periods of heavy engine load should help increase cooling significantly, provided the radiator area is clean as mentioned above.
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Old 05-18-2006, 04:43 AM   #13
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Hi Buck & Jeff - That's an interesting conclusion about the mode button. I went to an Allison seminar at an FMCA convention and they said to use the 'economy' mode. The tranny does shift up sooner to limit the engine at peak torque but your real-life experience in a fleet situation can't be discounted. I have never had to manage (manually shift) hill climbing before yesterday so I am a little puzzled.

There is a Freightlines Oasis dealer in Rapid City (20 miles away) and I'm going to stop in there today in the Jeep and chat with them. I'm now leaning towards the possibly of the coach having fan controller problems.

BTW - Jill at The Lodge says hi also
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Old 05-18-2006, 10:39 AM   #14
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Here is my two cents worth. Actually it comes from a trucker whom has been driving for about 60 years......he is 77. This is how he has explained it as I remember .

When climbing a grade the turbo is boosting the the intake charge at a high level of boost. That raises the temp, along with all the fuel being poured into the cylinders . Dropping a few gears lowers the boost, spins the fan faster and lowers the fuel being delivered . His advise to me when climbing a long grade is to downshift sooner and keep the RPM around 1900-2100. It has worked for us. High boost also increases EGT, also the reason for high temp, but most of us don't have that gauge. If I had that gauge I'd drive by the EGT temp, but instead I use the boost and try to keep it as much as possible below the max(24.3), when climbing the grades.
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Old 05-18-2006, 03:39 PM   #15
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<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by John_Canfield:
Hi Buck & Jeff - That's an interesting conclusion about the mode button. I went to an Allison seminar at an FMCA convention and they said to use the 'economy' mode. The tranny does shift up sooner to limit the engine at peak torque but your real-life experience in a fleet situation can't be discounted. I have never had to manage (manually shift) hill climbing before yesterday so I am a little puzzled.

There is a Freightlines Oasis dealer in Rapid City (20 miles away) and I'm going to stop in there today in the Jeep and chat with them. I'm now leaning towards the possibly of the coach having fan controller problems.

BTW - Jill at The Lodge says hi also </div></BLOCKQUOTE>

Hi John,

Thanks for sending our best to Jill... She's a terrific soul.

We have also experienced the same issues with heating that you have. Like you, I think the fan controller, or some part of that system, may be at fault. Our fan does not operate agressively until the engine coolant is already quite hot. If you learn of any service campaigns, or other fixes, please let us know.

It's been on my list for the next visit to the incredible Freightliner of Arizona.

The effect of what Tom and Patty are saying below concurs with what we were trying to say. Get the RPM's up, and let the engine "breathe" easier...

But again, for those of us with the evolution chassis with the side radiator configuration, I suspect there is some advancing of the fan controller to correct, or at least mitigatge this issue.

Cheers.
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Old 05-19-2006, 05:57 AM   #16
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Tom & B&J - absolutely good advice about keeping the RPMs up. I can say for a fact that going from 1500s to 2000+- RPM brought down the temperature.

With our VMSpc engine monitoring system I can look at intake manifold temperature which I think is as good or maybe even better than EGT monitoring. However, I need to make that gauge much larger and more prominent so we can keep an eye on it. I need to set an alarm for this parameter so I can immediately take steps to keep the temp down.

We stopped by Freightliner of Rapid City yesterday and talked the issue over with the service manager. He apologized said he couldn't get me into the shop until about 2 PM that day - WOW a service appointment that fast ?!? Told him thanks, but how about next week.

We have an appointment for next Wednesday morning; a tech is going to ride with us while they are plugged into the ODBII port. We are going to recreate the hill climbing activity while pulling the Jeep so we will see what's going on. If there is no trouble found, then we have to pay for the diagnosis (which is okay with me for peace of mind.) I sprayed Sinmple Green on the radiator and rinsed it off yesterday, but it didn't look too dirty. I probably should have waited to clean the radiator so we had the same scenario for the test ride - oh well...

B&J - the service manager told me the radiator fan doesn't cut in until the temperature is 205 degrees. I thought that was very interesting and that confirms your suspicion about the fan not running aggressively. Perhaps the logic is to keep the fan off as much as possible for fuel economy reasons?
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Old 05-19-2006, 07:56 AM   #17
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May I weigh in as an old engine tech

1500 rpm, heavy load, i do not know your rear gear ratio but I seculate its around a 4.30 or numerically lower maybe 5.30 .
anyway
1500 rpm is not really in the ISB power band, its just inside the low range, still has a good amount of tq, but its working harder than it should to maintain that tq, that is why power came up and temps dropped when you down shifted and let it run up in the 2k range

the engine was lugging and like was mentioned creating a ton of heat in teh combustion process,(pouring fuel, with not enough fresh air coming in) you mentioned Exhaust temps but i dont know if you have an exhaust gauge, if you do, a good rule of thumb is to drive using it as a reference stick , 1250 F is a good point to start watching it, 1350 start pulling back the throttle or down shift and get rpms up so more AIR can get in and out of the engine to expell the heat.
1400F and above can be detrimental to piston life , transinet through 1400 even 1500 wont necassarly hurt the pistons, but more than a transient could start the burn a hole process which will leave you stopped by the road
so when your running down the road and you start slowing down and increasing throttle and rpms fall off , dont be afraid to down shift, you wil burn more fuel at a lower rpm LUGGING than downshifting and gettign back into teh powerband
aslo I am sure the ISB engine has the latest electronics and it will start shutting off fuel if you exceeed some parameters like boost or exhaust temps, but if you dont have a boost and exhaust temp guage you might want to consider getting them, I have seen the plug and play screens that will display all of your engine readings under way, if you dont want guages.
hope the tech can shed some more light on your situation.
see you down the road

also with simple green, and aluminum radiators,
ensure its all rinsed off, even rinse several times to ensure its all gone,
the chemical di-limolene will react with the alum and cause corrosin issue if left to dry .
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Old 05-19-2006, 08:31 AM   #18
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Correct me if I am wrong, but I think John's rig has the ISL engine, not the ISB.
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Old 05-19-2006, 09:18 AM   #19
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Whoops my bad
that does make a difference on tq
ISL 400 1200 lbs @ 2200 rpm
ISL350 1250 lbs @1400 rpm
ISL350 1050 lbs @ 1300 rpm
page 6

maybe it will help
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Old 05-19-2006, 03:10 PM   #20
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Hi Robert - thanks for the info. We do have the ISL 400 HP. The Cummins ISL 400 brochure I am looking at shows the ISL 400 developing 1200 ftlbs of torque at 1300 RPM and keeping it at 1200 ftlbs until 1500 RPM. The torque rolls off dramatically after 1500 RPM and winds up at less than 950 ftlbs at 2200 RPM. Peak horsepower is developed at 2000 RPM though but that's not what gets you up the hill!

Being an instrumentation lover, I would like to have an EGT display - no joy there.

You are correct about the engine protecting itself from overheating - that's exactly what the service manager told me yesterday. He said some of the application programming will derate the engine and others will actually shut it down completely after 30 seconds or so - depended on the use (trucking, motorhome, cement mixer, etc.) I had completely forgotten that the engine and transmission logic was designed to save the parts from destruction.

Thanks for the heads up about rinsing off the Simple Green - I think I flushed it pretty good but maybe I ought to give it a few extra squirts for good measure.
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