Overheat on Long Grade

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Overheat on Long Grade

September 21, 2014, 12:06:35 am

I was wondering if any of you have ever overheated on a long grade before. We overheated (well got to the max cummins recommends) today in 3rd gear at 40mph, 1900rpm pulling the grade on 50west from Reno into Lake Tahoe. It was an absolutely ridiculous climb, from 4000 to 7000 feet in only a few miles. Felt like 8-10% grade. It seemed to go on forever. Even so I was surprised to see the temperature keep climbing. I stopped at around 210 degrees and ran it on high idle for it to cool down. Not sure if I should have packed it in earlier. We disconnected our heavy toad and it was at 180 the rest of the climb (but we were already almost done). It's a very odd thing to have so much power and not enough cooling capacity. Our old gas motorhome threatened to go backwards on nearly every hill but it wouldn't overheat even in 100 degree heat.

Now Lake Tahoe traffic, that was another story

Re: Overheat on Long Grade

Reply #1 – September 21, 2014, 01:06:14 am

Hi piku,
Was that temp from the dash gauge? If so, you might not be that warm. I thought our Cummins engine would go into a shut down, or alarm, if it was overheating.
Raymond

Re: Overheat on Long Grade

Reply #2 – September 21, 2014, 02:29:43 am

Quote from: piku – September 21, 2014, 12:06:35 am

I was wondering if any of you have ever overheated on a long grade before. We overheated (well got to the max cummins recommends) today in 3rd gear at 40mph, 1900rpm pulling the grade on 50west from Reno into Lake Tahoe. It was an absolutely ridiculous climb, from 4000 to 7000 feet in only a few miles. Felt like 8-10% grade. It seemed to go on forever. Even so I was surprised to see the temperature keep climbing. I stopped at around 210 degrees and ran it on high idle for it to cool down. Not sure if I should have packed it in earlier. We disconnected our heavy toad and it was at 180 the rest of the climb (but we were already almost done). It's a very odd thing to have so much power and not enough cooling capacity. Our old gas motorhome threatened to go backwards on nearly every hill but it wouldn't overheat even in 100 degree heat.

Now Lake Tahoe traffic, that was another story

Countless discussions of this with customers and industry people starting in 1985.

Personal experience today on a similar hill. Came over grapevine, ca at 5pm today coming from yosemite.

Started up the grade at 86 degrees ambient.

Coach ended up at 52mph at 1,700 in fourth. Floored.

Dash temp gauge pegged at a similar 210.

Five or six miles later the top was reached and the temp slowly dropped as the 3,000 pounds of engine and trans and cooling system cooled off.

You had nothing wrong IMO.

Everyone panics if the temp gauge moves. Do not.....

Repeated personal tests of multiple coaches and brands up steep grades at full power has shown me and my,customers to admire the cooling systems design from Foretravel.

Hard to overheat. My respects to the 6v92 people who know their engines will fail over 210(my personsal long term testings says no) but your coach is fine.

Actually its perfect IMO.

And I have driven diesel pusher coaches in the Rockies since 1984.

Every owner panicked if the temp gauge moved.

No coach has enough reserve cooling to not have the temp gauge move and the cooling fan increase its speed to add cooling.

Wish I could have had the skeptics with me today up Tejon grade. Taken countless customers up the same hills to prove to them it won't melt down.

My money. My coach. Been to 225 engine temp at 102 ambient. Exactly the same engine temp difference as the ambient temps were.

The same results I noticed in the 80's delivering coaches though the desert to Vegas.

Temp gauge was 210 at 80 degrees up Baker grade(17 mile grade) 240 at 110 outside.

Same hill. Similar new coach. Multiple coaches in both seasons. Me driving.

Sorry for the long explanation but after dozens of drives to prove what I am posting without a single problem or long term issue with coaches I feel qualified to post this.

Trust me. It normal. Notice no warning lights came on? Dead giveaway.

Bob.

Go ahead tell me you had problems after 210 or 220?

Re: Overheat on Long Grade

Reply #3 – September 21, 2014, 04:25:33 am

I may be wrong but on the M11 it doesn't send an error code until 220F. I think you will get an engine shutdown 30 seconds after the error code. Now at 210F steady state I wouldn't be concerned enough to shut down, but I would likely reduce power a little. If it was 210F and rising, I would definitely reduce power and let the coolant system catch up. I would also get my gauge checked. A 15 year old gauge is not likely to be that accurate. It could easily be wrong in either direction. That is one thing I like about the VMSpc, it gives you the digital data the computer is seeing and you can see the parameter changes over time letting you now if you are rapidly or slowly reaching a limit situation.

Re: Overheat on Long Grade

Reply #4 – September 21, 2014, 07:52:45 am

200F is my limit on my 6V92. Once I hit that mark, I reduce speed and power until it cools down. However, I grew up with the old 2 strokes in trucks. We frequently got 300K+ on an engine before anything other than regular maintenance had to be done. My all time record was a little over 400K on a 8V71.

You can certainly run these engines at higher temps than I do; but you will be working on them before you hit 200K.

On the other hand, most motor homes don't last that long. I had hoped Foretravel, like Bluebirds, were on the list of those that do.

I have no experience with the newer engines, but other mechanics I know tell me they will tolerate and in some cases thrive at higher temperatures.

I like what Bob said: My coach & my money, I drive it like I want!

TOM

Re: Overheat on Long Grade

Reply #5 – September 21, 2014, 08:20:18 am

The Cummins M 11 is a long life engine. With reasonable care, you can easily expect 600K miles. With the Detroit series 60, you might get 1,000,000 miles. Either one will out last the old two bangers, but I do love those 2 stroke Detroits ---- I grew up in the marine industry with the 71 series. I'm pretty sure the Foretravel chassis will outlast me if I take care of it. They are well built and durable.

Re: Overheat on Long Grade

Reply #6 – September 21, 2014, 08:50:38 am

Quote from: Kemahjohn – September 21, 2014, 08:20:18 am

The Cummins M 11 is a long life engine. With reasonable care, you can easily expect 600K miles.

With good care you can get over a million miles on an M11

Roland

Re: Overheat on Long Grade

Reply #7 – September 21, 2014, 09:11:23 am

I'd have to agree with all these folks who know more about this stuff than I do... the only caveat I'd add is that this assumes your cooling system is in good shape, radiator not clogged and such, that it's OK for things to get that warm climbing that hill. You ain't kiddin, that is one serious grade, and you're pushing many tons up it... but it's commercial-grade big truck hardware doing the pushing. Our old u280 with the lil kittykat engine handled some truly long hard climbs on our Yellowstone trip without complaining, it was amazing and gratifying to see just how fast temp would come back down once we reached the crest. Many's the time we had to park out SOB to let it cool off...

Re: Overheat on Long Grade

Reply #8 – September 21, 2014, 10:15:02 am

One reason we LOVE having the Silverleaf display ... you can read the "load" on the engine and the temperatures when you hit an area like that. We learned how to adjust gears and speed to keep the load in a good range and can only imagine what we were doing before that education!

Re: Overheat on Long Grade

Reply #9 – September 21, 2014, 10:26:44 am

i have hit 210 before on a long grad with an outside temp of 108 in Rapid City SD going west. It went up so I took my foot out and put the load at about 95% and it stayed there till I finish3ed the climb then it went down. We have to pull air and not push it and altitude makes a difference too.

Re: Overheat on Long Grade

Reply #10 – September 21, 2014, 10:30:48 am

Quote from: Carol Savournin – September 21, 2014, 10:15:02 am

One reason we LOVE having the Silverleaf display ... you can read the "load" on the engine and the temperatures when you hit an area like that. We learned how to adjust gears and speed to keep the load in a good range and can only imagine what we were doing before that education!

One of the things I'd like on our little old all-mechanical Cummins 5.9 would be a Silverleaf display but the two are simply not compatible. I worry about high temps on long mountain grades (and we have plenty of both of those where we live). I see the engine water temp go over 200F and immediately start to get concerned... but I always wonder just how accurate that gauge is. My suspicions are that it's not very...

I think I'll see about setting up a way to monitor things a little more accurately using my Raspberry Pi and its ability to deal with the real world and then display that on a web page that I can get to with a smart phone or a tablet.

We really like our U225 because of its light weight, lower overall height, narrower footprint and excellent fuel mileage. Plus it's creature comforts inside. Not to mention the snappy performance (50mph or better at the end of every on-ramp we've used so far (except for serious up-the-hill ramps in the mtns).

No way to duplicate the Silverleaf's ability though. Maybe I can come close...

Craig

Re: Overheat on Long Grade

Reply #11 – September 21, 2014, 11:03:43 am

Craig, I thought I should share some of my experiences with our 1993, U225 regarding over heating. This was the first diesel I had ever owned. I noticed that in the hot Oklahoma summers, 95 degrees plus, the temp gauge frequently exceeded 200 degrees, even on small long hills. I asked the local Cummins dealer a number of times as well as the national Cummins Tech line and even one of their top tech people at an FMCA convetion what the maximum temp of the 5.9 should be. I got different answers from every one ranging from 185 to 225 degrees. I spent close to $2000 trying to cool down the coach and became obsessed with the temperature gauge while driving. I replace the radiator cap, which was bad, then had the radiator pulled and cleaned (it was in pristine condition when we got it apart), a new water pump, and thermostat installed with no noticeable change. Oh, I also bought a new temp gauge and sending unit from Foretravel to insure that the gauge was correct and verified that the gauge was correct. Nothing seemed to change. I did find that the temperature gauge read about 5 degrees higher when the headlights were on, I presume due to lower voltage to the gauge at the dash.

One day I accidentally turned on the heater while chugging up a hill and the temp gauge dropped 10 degrees. That prompted the idea of install another radiator behind the grill and A/C condenser and plum it into the heater return hose behind the heater core. This dropped the running temps by an average of 10 degrees during hot weather.

Finally after all of these efforts I read there was a Cumming Technical Bulletin regarding maximum temps for a Cummins 5.9 available. I followed the link and discovered that the B5.9 had a maximum running temperature of 240 degrees. Finally I had it in writing, a specific guideline on that engine but I never quite believed it and never got over my obsession with coolant temps. I watch my Silverleaf Temp on my U300 constantly.

I'm sure you will want to see tat Tech Bulletin, others have asked previously, but unbelievably I cannot find it on my computer. I have also tried to find a reference to it on the net and as before have not been able to locate it but I did see it with my very own eyes and yes I was sober. The following which is more believable was in my archives for the U225 but I don't recall the source.

Standard Modulating Thermostat - Range
B3.9, B4.5 and B5.9....................82 to 93°C [180 to 199°F]
B4.5 RGT....................88 to 97°C [190 to 207°F
Maximum Allowed Operating Temperature
B3.9, B4.5 and B5.9....................102°C [215°F]
B4.5 RGT....................107°C [225°F]
Minimum Recommended Operating Temperature....................71°C [160°F]
Minimum Recommended Pressure Cap....................48 kPa [7 psi]
Maximum Recommended Pressure Cap....................103 kPa [15 psi]

Never operate the engine without a thermostat. Without a thermostat, the coolant will not flow to the radiator and the engine will overheat.
The illustration identifies the significant features of the coolant system.
Sections A and B.
Coolant is drawn from the radiator by the integrally mounted water pump. The output from the water pump empties into the oil cooler cavity of the cylinder block.
The coolant then circulates around each cylinder and crosses the block to the fuel pump side of the engine.
1.   Coolant Inlet
2.   Pump Impeller
3.   Coolant Flow Past Oil Cooler
4.   Coolant Flow Past Cylinder Head
5.   Coolant to Cylinder Head
Sections C and D.
Coolant then flows up into the cylinder head, crosses over the valve bridges, and down the exhaust manifold side of the engine to the integral thermostat housing.
As the coolant flows across the head toward the thermostat housing, it provides cooling for the injector. When the engine is below operating temperature, the thermostat is closed, and the coolant flow bypasses the radiator and goes to the water pump inlet through internal drillings in the block and cylinder head.
1.   Coolant Flow from the Cylinder Head
2.   Coolant to the Thermostat Housing
3.   Coolant Flow Past Injector
4.   Thermostat
5.   Coolant Bypass Passage
6.   Coolant Flow to Pump Inlet
7.   Bypass Closed
8.   Coolant Flow Back to Radiator
When operating temperature is reached, the thermostat opens, blocking the bypass passage to the water pump and opening the outlet to the radiator.

I hope this info gives you some solace and comfort and prevents you from wasting a lot of cash for nothing. To the best of my knowledge the B5.9 can run all day at 215 degrees, however I still would not be comfortable myself running that hot.

Re: Overheat on Long Grade

Reply #12 – September 21, 2014, 11:09:54 am

We had no alarms or lights but I certainly would rather choose the shutdown point and allow high idle versus the engine forcefully shutting down and cooking the turbo. It really wasn't rising past 210 but I suspect it could have. I think the gauge is pretty accurate. It will go right to 180 in the morning and sit there until I hit some kind of grade. Unless it's in the mid 90's then it will go to 185 maybe cruising flat 62mph 1400RPM. We were climibing the grade in 3rd gear, 1900 RPM. I haven't really seen much difference as far as keeping cool and which rpm but I suspect somewhere around 1700 works best for my coach.

We are very very heavy. We had a full front tank of water, 110gallons, we full time so we have all of our stuff. We have full fuel and our GX470 is probably an easy 5000 pounds. I am not complaining. My wife however was making fun of me saying we wouldn't have this problem towing a trailer with the Lexus. I can't wait to be on the side of the road with a coolant hose popped :-P

Also cummins documentation states 180-212 for the M11. That's why I killed it at 210. I try to do my best to keep the 15-20 coach bucks in my pocket

Thanks for all the comments. You guys really put my mind at ease that our cooling system is in good shape.

Re: Overheat on Long Grade

Reply #13 – September 21, 2014, 11:39:05 am

Quote from: Carol Savournin – September 21, 2014, 10:15:02 am

One reason we LOVE having the Silverleaf display ... you can read the "load" on the engine and the temperatures when you hit an area like that. We learned how to adjust gears and speed to keep the load in a good range and can only imagine what we were doing before that education!

Carol,

The load you read on your display is the injector potential load or what percentage of the maximum fuel the injectors are flowing compared with the maximum amount the computer will let them flow. For instance, at idle, my Pro-Link reads abut 25% load and goes up as the RPM and speed increases. The computer readout and the actual load will both be 100% at full throttle on a grade.

Bob,

There is a big difference between a dry sleeve 71 series Detroit and the wet sleeve 92 series. Dry sleeve engines have an advantage as they can take higher temperatures because there is no sealing ring(s) that can fail and let coolant into the crankcase. The disadvantage is heat transfer is not quite as good and overhauls are much more difficult to do a good job as careful measurements have to be taken before the liner is pressed into the block by a machine shop. With a 92 series, the liners are user replaceable with better sealing rings made today than when the 92 series first came out. With the DDEC and wet sleeves, overhauls are much less expensive and take far fewer hours than in the old 71 days. That is why the 92 engines are called "premium" engines by overhaul shops.

In researching marine forums on the 6V-92TA, the recommended alarm temperature is 195 degrees. The engine was super popular in sport fishermen as the V configuration allowed for lower decks than the inline engines plus the engine was able to produce more reliable horsepower per cubic inch than any other engine with 525HP the most common number and 625HP in some boats. Naturally, the more HP, the shorter the engine life is. My ex-greyhound had over 900,000 on the original 8V-71 before it was overhauled.

Engine life depends on HP and owner maintenance. Detroit 2 cycles used in generators running close to a full load frequently pass 40,000 hours before any maintenance is needed. The 60 series Detroit is history with only the 2 cycle 92 series and the DD13, 15 and 16 being manufactured by Mercedes (MTU) today.

Next time you see a train, chances are it's a EMD 710 2-cycle (16 cylinders, 710 cubic inches per cylinder) powering it. The most reliable, most economical locomotive diesel ever made. Detroit just took their smaller highway engines and oversized them with modern improvements like clutched turbos eliminating the big power robbing blower.

Piku,

You were wise to watch the gauges. I just shift down and slow down until the temperature stabilizes at or below factory recommendations. Running above recommended temps may not cause an immediate problem but can shorten engine life and may not show up for thousands of miles. Also, good to remember that even though the coolant temperature comes down fairly fast, the oil temperature will stay up for much longer. Failure to allow the oil to cool down can still cause the turbo to convert the oil to coke and cause turbo failure with the possibility of engine damage because of that. So, fast idle the engine for several minutes after the coolant temp is normal before shutting down. Damage from overheating will cost in the $15K-$20K range.

Kent,

You were sure on the right track with your heater discovery. Foretravel missed the boat with all that grill area up front.

Pierce

Re: Overheat on Long Grade

Reply #14 – September 21, 2014, 12:50:00 pm

Piku,

You might want to check into your high/low switch on your fan motors. I installed a warning light on mine to tell me when high mode kicks in. I've found mine doesn't kick in until my gauge is reading close to 200˚. I've been told it should kick in around 190˚ to 195˚. It could be my gauge is off by a few degrees. I think I'm going to do what Dave Katsuki did and install a switch to manually activate high speed mode when I know I have a hill to climb. That way I can pre-cool everything down and have some reserve for the hill.

I've seen 2 types of high/low switches. Mine is controlled electronically via a solenoid where as others (Dave's) are controlled mechanically. I helped Dave install a solenoid on his (actually I just drove him around to several hydraulic shops as he gathered parts he did all of the dirty work

) to override the mechanical switch. He reported that he noticed a pretty big improvement in cooling on hills using it. He also promised to write up a tutorial on how to install one. I'm calling you out Dave!

When I get mine done I'll do a write up for electronic solenoid controlled high/low switches and report any improvements on cooling I see.

BTW on my coach I run in low speed mode > 90% of the time. Only on longer hills do I see high speed mode.

JMHO but at 210˚ I wouldn't be worrying too much. I would be gearing and slowing down to see if the needle would stay at 210˚. 215˚ I'd be looking for a place to pull over and cool down.

see ya
ken

Re: Overheat on Long Grade

Reply #15 – September 21, 2014, 01:09:33 pm

I agree with the post concerning the U280 with Cat engine. My old 1990 U280 with 3208T and the rear mounted Atlas industrial all copper 4 tube radiator never gets over 190 degrees no matter how hard you run it. I expect that the cost of a new radiator like that would be about half the value of the coach today! I'm still getting to the variable temp I see on my newer U320.

Re: Overheat on Long Grade

Reply #16 – September 21, 2014, 01:43:27 pm

Quote from: Carol Savournin – September 21, 2014, 10:15:02 am

One reason we LOVE having the Silverleaf display ... you can read the "load" on the engine and the temperatures when you hit an area like that. We learned how to adjust gears and speed to keep the load in a good range and can only imagine what we were doing before that education!

All I know is that when the load is reduced on a long grade, the temperatures reduced, as well ... may not be the scientific interpretation ... but it worked!!

Re: Overheat on Long Grade

Reply #17 – September 21, 2014, 01:53:09 pm

Pierce... thanks for repeating that. I had forgotten the 240F figure; you have quoted it before but I had forgotten what the number was. I am very tempted to do the same thing regarding the secondary cooler in the front. Did you mount yours in front of the A/C radiator? Not a lot of room up there but something would help.

Craig

Re: Overheat on Long Grade

Reply #18 – September 21, 2014, 02:22:54 pm

When temps increase a lot during a long climb, the throttle is usually being pressed too much and the gear selected too high and the speedometer is reading too high a number.

We spend hundreds on trying to reduce coolant temps and found that slowing down a lot and driving in a lower gear completely solved our high heat problems. We also watch our boost to be sure it is working and keep an eye on our pyrometer to hold it below 1,000 degrees. One eye on pyrometer & the other eye ball on tachometer, with someone else looking out the windshield. We don't worry about running into the vehicle in front as we are often going too slow up mountains.

Re: Overheat on Long Grade

Reply #19 – September 21, 2014, 02:29:52 pm

Craig,

That was Kent's post. While I'm installing my tankless block heater and exploring all the ways to run lines in the dark recesses of the coach. I am also figuring out how to run larger piping up to the nose for a couple of NASCAR type aluminum radiators right behind the grills. I would like to round file the whole hydraulic system and replace it with electric fans but there are not any that will do the job on just the existing side radiator. With a couple up front, I could go entirely electric and gain about 30 HP and some fuel mileage to boot. Every time I look at all the belts, pump, motors, shrouding back there, I get mad.

Lots of options on ebay for aluminum radiators and they are a tiny fraction of what Foretravel would charge for the OEM side or rear radiator. Easy to mount up front and they would take advantage of ram air going down the road. The heater hose is a little on the small size for moving coolant up front to a couple of good sized radiators so that is the reason for finding an alternative path to the front. No problem going through the any of the compartments. It's just the first few feet from the bulkhead to the wet compartment that poses a problem. I suppose I could go up into the closets and kitchen compartments and then back down but would be a lot of work. Was thinking about 1-1/2" ID piping. Our U300 has a lot of room up in the nose for any kind or number of radiators. Think two with a set of electric fans behind them would be perfect.

Yes, the AC condenser would have to be moved but we always run the generator and roof ACs while underway so not worried about it.

As it is, we can run flat out up the grades unless the ambient goes over about 85 or 90 degrees. Then I have to watch the gauge. We came up and out the steep side of Death Valley to Highway 395 pedal to metal all the time without going over 195 . Same way with I-80 and Donner Pass at 57 mph in third gear unless it's warm outside.

Pierce

Re: Overheat on Long Grade

Reply #20 – September 21, 2014, 02:58:49 pm

Piku you did the correct thing by cooling it down although maybe you didn't need to, but why take a chance. The only thing I can add to this is that I found leaves on the radiator behind the charge air cooler. The side mounted radiator does require the fans to pull air through it, and being mounted behind the rear wheels it does pick up a lot of dirt that can cut efficiency.

Re: Overheat on Long Grade

Reply #21 – September 21, 2014, 03:19:07 pm

Road crap between the CAC and Rad is caused by it being thrown up from duals and there should be some belting fastened under them to prevent this. I also put some more down both sides to sort of close the whole perimeter off so air has to come thru grille and CAC. I do not have any issues with heat while climbing the Grapevine etc but I also do not have tons of extra weight behind in the towed. My tracker is heavy enough to go shopping and sight seeing but does not cause coach any problems.
JohnH

Re: Overheat on Long Grade

Reply #22 – September 21, 2014, 03:31:10 pm

I decided to bite the bullet and install a secondary cooler (a la Pierce) for the U225. There is room for a small unit up forward and I think a handy-dandy set of ball valves would make it easy to put on-line or take off-line. In fact, since summers here typically run in the high 80s and low 90s (with excursions above 100 more frequently) just leaving it in the circuit from June through August would not be an issue.

About $30 with tax from Amazon. Should work at least as well as turning on the heater.

Amazon.com: Hayden Automotive 402 Ultra-Cool Tube and Fin Transmission Cooler:

Craig

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

Re: Overheat on Long Grade

Reply #23 – September 21, 2014, 03:41:01 pm

Craig,

Good idea, but I would use a real radiator up front, not a transmission cooler. And, as you suggest, use ball valves and the existing dash heater hoses to bring the coolant from engine to the front.

Before deciding to leave it open all the time, even in summer, I would see how much it delays reaching operating temperature from a cold startup. If no more than a few minutes, leave it open. But you DO what the engine to get up to operating temperature pretty quickly.

Re: Overheat on Long Grade

Reply #24 – September 21, 2014, 03:51:56 pm

Cat, Cummins, DDC & Kubota teaches min water temp is controled by thermostat, not radiator size. Unless there has been a change in physics ?

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