We are presently in Mammoth Lakes, Ca (8,000') where we have vacation house. There is a long steady grade that gains 4,000' from Bishop, that has always been a problem for us in a motorhome. This time we detached the Jeep and my coolant temps. reached 221 degrees. Last year I replaced the radiator and transmission cooler (and hoses) and put in an exhaust resonator. With the ISM engine, I don't expect to have this problem. When approaching a long grade, I drop to 5th gear and keep the rpm's in the 1700-1800 range going about 50 mph, dropping down to 45 mph as needed. There doesn't seem to be a problem with the power, if I ignore the temps. The weight of the coach is just over 30,000# so this should not be a problem.
Any suggestions?
In the archives I read about Barry's problem that seemed to be caused by the fans not working at high speed. Can't tell when the fan changes from one speed to the other. Shortly after I changed out the radiator, I had difficulty maintaining the proper coolant level. On one occasion, the overflow tank spewed coolant onto my toad, leaving white residue. That doesn't seem to be a problem now, but I find that I have to refill my reservoir frequently. I considered the problem of air in the system, considering the radiator change out, but had hoped the air would have worked its way out by now.
Boil over is 265. Driven up countless grades up to 230+ since 1984 including Sherwin grade you mentioned.
Your motor has an electric cooling fan temp control on it to trigger a front mounted engine cooling fan on a truck.
It's turn on point is 210 degrees F.
I spent lots of hours discussing this exact scenario with owners long ago.
All were concerned if the temp gauge moved.
My customers who ran fleets of garbage trucks mentioned their trucks ran 230 a lot and the trans at 275 continuously.
If you pass 230 much and the gauge continues to climb a load reduction and a gear down might be helpful.
At 220 sounds like it's working perfectly. No coolant loss I presume?
Not possible to put a big enough radiator to never have the gauge move.
Foretravel original Unihome had the same radiator for the u280 with the cat and the u300 with the Detroit.
Factory had to block off part of the radiators on the u280's as the cat never warmed up completely.
Passed a lot of rv's on grades because of this.
The Detroit's may not like being hotter over long run according to some here.
Delivered dozens on u300's up baker grade going to Vegas for out of state deliveries at 100 degrees plus and demonstrated that the gauge stopped climbing at 230-235 F to the future owners.
Versus drive in the middle of the night to not have the temp gauge move like a lot of customers were doing I demonstrated no damage or coolant loss occurred.
I hit 230 or so on a lot of western grades in the summer. No issues.
I can almost see the raised eyebrows out there reading this.
Go slow if you are not comfortable with what I post.
I thought it was more dangerous to pull over on grades and then try to blend back in up hill into traffic slowly which is why I researched this. Then tested it a hundred times. Then demonstrated this to customers.
On my dime ,in my m11 coach, I would have and have passed a zillIon coaches up grades in the West in the summer heat
Sounds like yours is perfect to me.
If the gauge stops at 230 or so everything's fine IMO.
Drove beavers, country coaches, monaco's, blue birds and prevosts exactly this way without issues
Going up hills, if I don't like the temps I see, I drop down another gear and go from there.
Try the same hill in 4th going a bit slower with more RPMs to reduce coolant temp. I have done a fiair amount of mountain driving in our coach and I an not sure if I have seen coolant temps over 210. It might not hurt to get hotter but it doesn't hurt to stay cooler.
I have run that grade a bunch, no higher than 220 ever. Just drop a gear and enjoy life. If you continue to have to add coolant you have a leak or air in the system.
Is your trans cooler disc installed? We consistently blew out coolant until finding out ours was missing. Haven't lost a drop in two years.
We go up Sherwin and Conway all the time did it again a couple of weeks ago. Put a test light on the fan switch to see if your fan goes into the high speed mode. Run it up into the bedroom and have someone watch it. You could also use one of the extra wires that goes up to the front and put a light on your dash to indicate the high speed position.
Your Cummins and our Detroit both have wet liners. They don't tolerate high temps as well as parent bore engines like the smaller Cummins and some CATs. I let the temp gauge go two needle widths above 212 max.
Summer temps make a big difference. We can charge up out of Death Valley in winter without a problem but in summer, I've had to go down into first gear.
You might check your pressure cap to make sure it's working OK.
The effects of overheat are cumulative so it pays to be on the conservative side.
Pierce
If your temps get to hot for the setup wont the computer shut it down? I have climbed Baker grade in the heat of the summer and I think it was 222- 223 area.. I think at 225 the computer starts complaining.. I think?
David,
That's like the idiot light for low oil pressure. Use it too often and ...
When the ECU goes into shut down mode, you have partial power for 30 seconds then the engine shuts off. If you are in a place where you can't pull off, your personal safety is at risk.
There is an override switch on the dash. One Detroit owner lost a hydraulic belt just before entering an uphill tunnel. He used the override but it shut down again after a few seconds. Not to be deterred, he used it again and again. He got to the far side of the tunnel but the toll charge was almost $30,000 for a new engine. The block was too distorted to rebuild.
Pierce
ISM Engine Protection Theory of Operation - Cummins Engines (https://cumminsengines.com/powerspec-ism-engine-protection-theory-of-operation)
Go slower. . . Certainly go slower until you figure if you have a problem. Why push it. Wonder what exhaust gas (pyrometer) temps are.
Transmission cooler disc? My cooler is pretty straight forward. Four portals, two for coolant and two for trans. fluid. The transmission temps have been good and I have not detected leaks anywhere.
I did go slower and did drop two gears. Third was the next one down and that over rev-ed. Should I expect to go 40mph in fourth gear without a toad to avoid over heating? I could have done better than that with my Safari with small CAT. After spending the money on the ISM and replacing radiator, etc, I expect more, and from what I've heard and read, others aren't experiencing this problem. I don't want to have to stress every time I go up a long grade or have to disconnect the car. For those that suggested dropping a gear and running up the RPMs, which gear and how many RPMs?
I'm interested in knowing more about the trans. cooler disc, where it is located and about its function. The test light sounds like a good idea, once I figure out where to attach it.
"I hit 230 or so on a lot of western grades in the summer. No issues."
Caflashbob, the only time I hit 230 and trans temps in excess, my engine check light came on and the engine de-tuned (lost power), almost before I could find a safe place to pull over. It was after this experience I changed out the radiator. Your M11 may be different than the ISM.
Your Safari was much, much lighter and the small CAT was a parent bore engine. DPs get no ram air to aid cooling. Just an inefficient hydraulic system that has to move all the air on it's own.
Some members have installed radiator sprayers to keep temp down. You need to use RO water to avoid the white calcium deposits. I think this is a good idea but have not had the time to do it.
I even turn the heater on with the fan on high. The engine temperature gauge reads higher with the heater fan on by about 15 degrees. The heater does work to reduce temps. I just hate to think about the work it will take to bring larger hoses up to the front.
Check your 12V schematic for where to put a test light to see if you are getting high RPM.
I drive in the gear and RPM to keep the temp at bay and don't worry about the speed. I have plans to put a couple of big aluminum radiators up front but that's not an option for you with the bus style front end.
Pierce
The Safari was about 2000# lighter and had a rear radiator, which worked to contain the heat in the engine compartment, but don't want to spend time with the comparisons. The FT has many more features that I prefer. I won't put down the Safari, because I believe it was a fine RV and well made.
Back to the issue: I use distilled water for the radiator, which should be better than RO. As far as I remember, it is as pure as water can get, devoid of all minerals which are precipitated out in the distilling process (we did this in chem lab back in the "college days").
I always use the dash heater in these situations and the ambient temperature was under 80. The only remedial action that I didn't take was opening the cowling (engine compartment door). I also base my driving on RPMs and temps. How fast I am going is indicative of the engine performance.
Sorry if my frustration comes through. The only thing that has made sense so far, is the fan speed, it might not be kicking into high.
Sven,
Sorry, I know I should have been clearer. The RO water was for the sprayer that some have made to spray water onto the front of the radiator to aid in cooling. Since RO water is free (if you have an RO system) that's the reason I suggested it. Usually, schedule 40 is used with brass misters and a 12V pump to supply the pressure needed. misting nozzles | eBay (https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313.TR4.TRC1.A0.H0.Xmisting+nozzles.TRS0&_nkw=misting+nozzles&_sacat=0&LH_TitleDesc=0&rmvSB=true&_osacat=0&_odkw=132521456791+)
12V 1 GPM/100 PSI high pressure pump for misting system: New Solid 100PSI DC 12V 1GAL/Min Diaphragm Water Self Priming Pump High... (https://www.ebay.com/itm/New-Solid-100PSI-DC-12V-1GAL-Min-Diaphragm-Water-Self-Priming-Pump-High-Pressure/131556382165?epid=1577467710&hash=item1ea15f15d5:g:vvEAAOSw3ydVoN~s)
Pierce
I vote for the mister. I did the redneck version. 1/4" plastic tubing zip tied to flat stock double stick taped to the radiator, 1/4" NC solenoid tee'd into the pressure side of the fresh water pump, and a switch to the solenoid on the dash. I used it a least a dozen times just coming across southern Tennessee (Hwy 64 E) today. Temps were high 80º low 90ºs. I never hit 190º. This is in a coach that fires on every stroke, is overloaded (fulltimer), dash air on, towing a 4600lb car, and the drivers foot gets heavier as the day goes on.
This simple cheap hack is one of the best things I've done to my coach. It does require more involvement by me driving as I have to decide when to use it and how long to leave it on. My goal usually is to never have the fan kick into high speed mode. I did as Pierce suggested above and ran a light to my dash for a visual aid. On mine when the light is on it's in low speed mode. Light off it's high speed.
If I don't do anything high speed mode comes on at 185-187º reverts back to low speed at about 184º. YMMV
The cheapest easiest solution is Barry suggestion. Relax slow down. Go to 4th. The mountains have the best scenery!
Edit: to change NO to NC!
see ya
ken
Mister on 94 6v92, works great on 2 Alaska trips
Pictures
The early coaches had low/high electrical switched fan controllers
Later coaches went to a variable speed hydraulic fan controller.
Foretravel used a 165-180 way too conservative fan controller.
The rest of the industry used a 185-199 unit.
I and bob rozen both changed our coaches to the 199 degree unit.
In the posts here there is a mention of a disk in the thermostat to divert antifreeze for the trans cooler if memory serves me.
Some engines had the disk. Some did not it seems.
Thermostats do not open fully until 195
I personally convinced the Gillig rep to reprogram the beavers coaches engine shutdown settings as they were ridiculously low.
Don admitted they were way off finally.
We were in the edge of the desert and you had to go uphill to get out of so cal.
Bad in the summer,
Customers leaving at 4am to avoid unnecessary warning lights and power downs.
I had long talks with all the motor guys. And all the chassis guys and the Allison guys. And my garbage truck fleet/owner customers,
I actually rode along with Garrett Box's guys to see how hot their garbage trucks ran.
Oshkosh sent two engineers to me in Ca and the cat guy showed up and we instrumented coaches to test things in the desert summer heat.
Late 80's time frame.
James T should remember this stuff. Ask him.
My local Cummins shop manager/owner laughed when I asked a few years ago if running current engines at 220-230 would damage them. No.
I just came up that grade out of Bishop yesterday towing my Grand Cherokee. Left the trans in economy and watched the VMSpc trans. got to 220 engine to 210, most of the time it was in 4th shifted to 5th a couple of times. 47 mph lowest speed reached at Deadmans summit.
Sven and Kristi,
When I look at your problem I am making the assumption that the M11 and ISM cooling systems are similar as we use the same radiator. With that in mind is there any possibility that the deaerator box & bypass hoses are reversed?
Are you certain the coolant overflow is coming from the overflow tank and not the deaerator box cap. Our overflow tank was empty and the deaerator box 1/2 full when we purchased our coach 10 years ago. After filling both several times I started looking at other possibilities. Head gasket? Nope. After going through countless gallons of coolant I finally made the connection. The transmission cooler was starved for coolant, when the engine thermostat closed off, going down hill. The coolant pressure was apparently suddenly rising , under the right conditions, that it would force coolant past the cap gasket. I was able to reduce the amount of leakage by bending the ears on the cap to get a tighter connection. This did not solve the problem but greatly reduced the frequency. Fortunately, finally I saw a post from prevostart about a orificed disc. Suddenly everything made sense. This disc would force flow to the cooler solving the low flow condition. Cummins verified that it should be there. Mine was missing. PROBLEM SOLVED!!!!!!!!!!!!!!!!!!!!
Caflashbob,
Just arrived in Sioux Falls SD.
2332 Miles/ 9.6 MPG/ 60-65 MPH Highway
I have recovered the entire cost of the replacement temperature control valve.
Thanks for the valve advice,
Bob
"Are you certain the coolant overflow is coming from the overflow tank and not the deaerator box cap"
Bob, this is new ground for me - I have never heard of any reference to a deaerator box or disc before this discussion. Your account of what happened to you prior to correcting the problem sounds like what I've experienced. When I was doing my radiator project, I did not replace the bypass hose your referenced. I would have to look at my engine to find it.
We will be stopping at Oregon Motorcoach in Eugene, OR this week for a windshield replacement on our way to Portland. I will ask them tell me more about it.
Thank you for pointing this out. Sven
George,
Excellent installation. Nice and neat. I don't recall any misters that are black and look like that. Description, source and price?
Ken, I remember when you really were battling overheating. What was your problem and solution. You sound like you have it cured.
What kind of water do you use? Filter in line? Do you get deposits on the radiator face?
Pierce
Bob I am Glad the higher rated fan controller worked for you also.
I squandered the better mpg by going faster. Get 8.2mpg at 75.
I do like the noticeably better torquer power from the resonator and lower power loss fan drive.
Engine downshifts much less. Pulls instead of revving.
Same exact temps on dash and silver leaf after the swap.
Thanks for the post on the disc. I think mine wrong also.
Will have the Cummins guys check it.
Only 9.6? Was it windy? Dumb question across the Plains.
Endless hills and wind. :o
Perfect conditions across Nebraska/Colorado at your speeds flat ground got into 11's.
Slight increase in mpg,I thought, as the batteries got full and the solar covered the coaches actual use driving.
Sven on my 99 there is a little silver box on back of engine compartment with wired and small hydraulic lines. this is the fan control box and I have read if you unplug it the fans run in high only. Apparently the PO had heat problems and when I got the coach the unit was un plugged. I am in need of a new radiator, so once that happens I plan to reconnect everything.
Chris
Allison Economy mode could save a few gallons of diesel but will always make that saving with increased engine stress and heating, which cannot make the engine last longer.
It is a balance between fuel cost vs engine wear cost. I think fuel MPG is way overstated as a goal for a 30,000+ pound vehicle, for the miles we drive in a year. A better goal would be to keep coolant temps between 180 & 190, mostly at lower end of spread. RPM, MPH & EGR gauges can keep temps in line, no matter the road incline. Keep cruise control turned off on up-hills. Maximum-speed is not a friend.
Agree. Think all coaches should have a EGT gauge [exhaust gas temp.]. This will give you an indication of load on your engine far faster than any temp gauge. Many big trucks come standard with pyrometers.
I can not get a straight answer from anyone at Cummins including the rep that sells Foretravel their engines to my inqiury as to whether the ECU reduces power until the motor is fully warmed up.
Thermostat is fully open at 195. Stock hydraulic variable speed controller idles the fans up to 165 not off because of the intercooler. 15 degree ramp up to 180. Full speed at that point consumes over 50hp.
My shop foreman noticed that my coaches hydraulic reservoir was really hot when I drove it on.
His comment was the controller locked on high as a normal warmed up thing could tend to overheat the oil and wear the fans and pump and power steering box which could cause premature leaking....
Plus reduce the mpg and suck up 30-40 horsepower out of the motor.
He knew of no other vehicle running a 180 max speed controller..
Fan on max always. Engine normally not warmed up fully. Restrictive probably rusted inside muffler heating the bedroom for hours after a drive.
Bob and I and others have noted the considerable improvement in power and mpg from these mods.
Coach was not fun to drive with it's constant downshifting under medium loads.
I posted here 6 years ago when I first drove our coach that something was wrong.
Plus leaking Winn fuel filter and cracked fuel lines and high rolling resistance tires.
Coach required less brakes then as the tires slowed the coach down.
Now I have to use the brakes much more.
It's not the mpg. It's the engines torque that was being consumed elsewhere in the coach.
I am surprised a 99 has a electrical high/low fan controller.
The internet upgrade from the Oregon people is the hydraulic variable speed controller
Everyone elses rv runs a 185-199 controller.
Yes I called Cummins southeast. No one there or at Cummins remembers what was in my 97's ECU.
Cold engines may tend to violate smog laws? Or the fuel might be reduced to not damage a cold engine?
Can you provide more details on this? I agree, running a diesel at too low a temp is not doing it any favors. The stock fan controller is a primitive solution.
Took,me a few minutes to find this info.
Source Engineering Inc | Custom RV Chassis | Eugene, OR (http://sourcerv.com/conversion)
http://sourcerv.com/tvck_flyer.pdf
Wax valve/fan controller - iRV2 Forums (http://www.irv2.com/forums/f112/wax-valve-fan-controller-379070.html)
Bob and I posted this info a while ago, please save the info.
Thanks Bob I appreciate you digging that info up. I'm trying to figure if this new wax valve is proportional varying fan speed based on temperature or just high and low. I do get that your conversion set high for a higher temp.
Proportional by coolant temp. See the link showing the install I posted.
I used to have the speed ramp up chart graphic. Let me look
Here is a graphic from a 4 year old post here
http://www.foreforums.com/index.php?action=dlattach;topic=22839.0;attach=28843
Had some thoughts overnight. I am thinking most m11 engines were speced to work with manual trans.
No need for the disk in the thermostat housing area. So logical none were installed.
Maybe Foretravel tested early m11's and noted some heating.
Not knowing why maybe the easiest fix was to max the cooling fan on by running the odd lower temp controller,
Maybe separately mis plumbing the de aeronator and overflow as Bob Rozen has found could be a separate issue.
That the prevost guys found the needed disk missing on 8v92 engines may indicate the same issue on engines shipped from Detroit.
It's been posted here that some had and some did not have the disc's in their engines.
The post of a 99 with a electric fan speed controller might indicate that Foretravel was testing alternatives to reduce temps maybe not knowing the disc?
Although Foretravel can build the system many ways maybe a customer asked for the electric fan speed low/high setup.
Or it was less money? Anyone else after 97 have an electric controller?
Maybe a call to James T.
Bob,
The M11 Cummins factory manual clearly indicates that a disc is absolutely necessary when a transmission cooler is used. Without the disc there is inadequate flow through the cooler. It would be interesting to find out how many have verified they have the disc. Could be related to cooler failures.
Or trans heating....?
Several posts here a while ago reporting both ways...if memory serves me.
Thanks for your info as my coolant recovery tank empties.
Early on I found that I would not lose any additional coolant once the system purged out enough to leave the deaerator box 1/2 empty and the overflow tank empty. With the orifice disc installed, the level now operates within the hot/cold levels on the overflow tank.
Hi Bob Rozek,
I am wondering where the "decelerator box " is located.
Jim
2002 U320 with M-11 and Aqua Hot
Deaerator box
The tank at the highest part of the cooling system (right side photo in post above) has a small hose that allows any air in the cooling system to evacuate into the tank. The small line in the pressure cap neck goes to the overflow reservoir. Our small line was leaking and had to be re-soldered. Pretty easy with a backerboard or something else flameproof placed above while soldering. The sensor toward the bottom will shutdown the engine if the coolant level falls below it. Keep the overflow tank level between the marks as indicted on the side of the plastic tank. Should be checked before you go anywhere in the morning. Goes without saying that the clear window must also show coolant at all times. Pressure cap can also be tested or just replaced if in doubt or loosing coolant.
Also that tank can be kept full and the overflow will work without overflowing. Just looked and mine is full and the overflow is at the cold mark. Traveled from Los Angeles to the Sierra's Saturday.
If everything is correct the coolant in the overflow tank will displace any air in the deaerator box as the coolant in the system expand and contracts.
Yes, the pressure/deaerator tank should be full at all times. This is why it's important to keep the overflow/expansion tank within the marks. This is exactly like most cars work.
How is the weather at Oh Ridge today?
Piece
We've been on the road for the last couple of days, so have not kept up on thread. If I put coolant in the overflow tank, it ends up spewing all over the Jeep. "Sumpin ain't right". We drove up the grade to Tahoe from Carson City and managed to keep the temp to 217, 3rd gear and 40 mph.
Tomorrow we will be in Eugene, Or at the Oregon Motorcoach Center for windshield replacement. I will ask them about it and the nearby Cummins facility that FT recommends. Hard to keep their mittens out of my pocket.
Sven,
Have you checked your radiator reservoir/pressure cap yet? A faulty cap will quickly fill the overflow tank and then out the back.
P
Have you replaced the radiator cap? An inexpensive first step.
The overflow container has a hose that will flow any coolant that overflows the overflow container, usually to the ground.
We extended this last overflow hose into a 2nd overflow container, and without it we would not be aware of this loss.
We have never seen anything in the 2nd bottle.