We are just south of Raton. We are towing Jeep Liberty.
I'm seeing temps over about 208-210 on analog factory dash temp gauge. I'm running about 63 mph, in Econ mode.
Should I have any serious concern other than continuing to monitor?
Assuming you have the 8.3 Cummins it's a higher then normal temp.Would check fans for turning, radiator for dirty fins, oil and coolant level and if you have one use a infared temp gauge to engine temp.PS,no clue where Raton is.
Couple of things:
Mode will make no difference at 63 MPH unless steep grades, you will be in 6th gear either way.
While the gauge may not be dead accurate, the fact that it is reading higher than normal means you are OUT OF COOLING CAPACITY.
Possible causes:
Thermostat not completely opening-- they ARE a wearing component.
Coolant level low-- when cold check at the pressure cap and verify that level in the overflow reservoir changes with coolant temperature-- level rises when coolant hot and lowers when it is cold.
Hydraulic fan issue. Start by checking fluid level in reservoir.
Dirt or debris in cooling package. Look in from the side of the coach and make sure that you didn't suck a plastic bag, etc.
Keep us posted on what you find.
Your coach still has a 5.13:1 axle ratio, which is a VERY good thing. We also towed a Jeep Liberty with our 1995 U295. In my opinion - despite the performance axle ratio - you're asking a bit much of your 300 hp C8.3 engine (in the Raton area). Have you checked engine temps when throttled back to 53 mph in 5th gear?
Larry
The 5:13's I thought could cause trans rear carrier issues? Replaced with 4:68's?
I agree with Brett as you seem to have run into some limit in the system.
The temp itself should not hurt anything as far as I know
I'd have the 5.13s installed on our new-to-us 2002 U320 if we could afford the swap. Our 1995 - with 5.13s, was a joy to drive (especially congested interstate on-ramps). The ISM equipped U320, with 3.91 gears, however is a chore to drive on those same on-ramps.
The temps look OK to me, if younare going over Raton Pass you should be in a lower gear, probably 4th watch coolant and transmission temps. Same gear going down with a notch of retarder.
Raton in July! I think your fine. The little engine that can!!! I try to keep the rpm's at peak torque value when pulling uphill
We run all over the west Montana, Idaho, Wyoming, never get over 205 MAX towing a 4 dr Jeep Wrangler gross weight 35000. Check all things mentioned above, and drop a gear or two. If you are pulling a hill you should be able to accelerate going up if you are in the proper gear. Keep you RPM 1800-2000.
U295 owner. The m11 is a much lower rpm motor. It's supposed to have a more torquey design than rev it up and use the hp to get up hills.
I sold beaver Marquis with 3176 cat engines that in the days of 55mph would not reach 70 mph. 3.91's with a 4 speed Allison in 91.
Speed limit changed but the Gillig chassis had the 55mph gears.
So I regeared them new to 3:21. Mpg went up. Coaches at 37,000 pounds combined weight went 65mph up all the interstate 6% grades with the cruise on and the jake held it back to the same 65 on cruise control 8.25 mpg
M11 does not have a much torque/hp as the Cat regardless of the respective ratings.
Cat turned up their motors for the rv manufacturers.
IF I could turn up the m11 I would regear it lower. 3:42's?
Being as I was unable to add power I went the other way and fixed all the parasitic draws and the tires rolling resistance.
Big difference after the changes.
Still needs more power. I know of a place that might be able to "fix" the power but it's on the other side of the country from me.
If it has more power versus lower the losses then you have more heating. Everything relates to everything else.
TINSTAAFL, There is no such thing as a free lunch for the Heinlein fans
Hi RPM keeps the coolant circulating best, keeps EGTs down, moves more of the thinner air over the radiator for better heat exchange. Not sure how 1800-2000 in a Cummins 8.3 translates to our 9.0 engine but I run close to 2000 ( 2130 fuel cutoff) unless it starts to go much over 200 degrees and then drop a gear, keeping RPM high close to fuel cutoff.
Low RPM on grades, especially high altitude grades is the opposite of what it should be.
Large engines should still keep RPM well up in the RPM range. High EGTs take a lot of responsibilities for dropped valves.
Pierce
And for those of you that think the 215 degrees indicated is the temperature your engine is at, think again. It's 215 where the temp sensor is, usually close to the thermostat housing. Right around the exhaust valve, the coolant is much hotter than that. The pressure cap at around 14 lbs is what keeps the coolant from vaporizing in these locations. If it does, the temps will really head up instantly in that spot and will allow the valves, cylinder head material and pistons to exceed design limits. The oil sprayers can only cool the piston crowns so much.
A listed 10,000 foot elevation pass in summer may be 13,000 feet or more with the radiator and fan loosing even more efficiency. EGTs will run even higher. Keeping the coolant circulating as rapidly as possible and the EGTs down is the best path for engine longevity.
Pierce
I can count on one hand the actual number of damaged Diesel engines I have seen in the rv biz since 1984.
Customers are too frightened to drive them hard at all.
Such a shame as they are needlessly afraid. My heavy user garbage truck fleet owners showed me how tough these really are/where.
Theirs rarely ran below 210 engine and 230 trans. Harabiedien had 165 garbage trucks and Garrett Box had a similar amount.
Just saying. New DEF motors dislike idling and have EGR issues.
All engines dislike idling, all engine manufacturers don't recommend it and it's against the law in many places.
When accelerating from a light or onto the freeway, I usually am at full throttle and let the computer shift the transmission at maximum RPM the ECU is programmed for. In our case I frequently run it up grades at 2130 RPM unless I don't have enough cooling. This is not running the engine hard. This is what is was designed to do, day in day out. It was not designed for operators operating on myths
Lots of diesels don't make it to their B50 life. Lots from the misconception that it was designed to "torque" it up grades and lots from operators making it a habit of idling their engines for extended periods.
Pierce
My favorite rv drive was a n14 444hp 1850 torque Monaco signature. Eaton economat 9 speed trans with 1 and 2 wired out.
You could not drive it revved. Too fast. It's the exception to the rule as was the country coach concepts with 8v92's and six speed trans. It would double the triple nickel speed limit as would the Monaco.
The cat marquis would torque better than hp up grades that's why I was disappointed with my m11 originally.
If you tell me it will last longer downshifted and revved I feel better about it.
The Cummins people tell me the sweet spot is 1350 to 1500 rpm.
Cm fore set up his coaches for almost 70 mph to balance the power versus mpg.
Mine seems to be not as much difference in mpg as the cat chart shows going from 65 to 70. Maybe half. About a half mpg difference from 63 or so to 69 or 70
Bob, you wrote 'Cummins said sweet spot is 1350 - 1500 rpm'. That matches my experience. The ISM supposedly has peak torque at 1200, but at that rpm, my engine doesn't pull at all, but wakes up at 1350 rpm.
Larry
You guys need EGTs installed close to one of the exhaust ports. Watch it and don't worry.
Pierce
Never seen a stock Diesel engine in a motorhome get anywhere near a damaging EGT. If memory serves me Bluebirds had gauges on both banks and the temps were always well within specs for no issues
But Bluebirds had Detroit 8V-92TA 2-cycles that don't have the EGT problem. That's part of the reason they don't blow up. Here is a shot of a 8V-92TA on the dyno at 800 hp and 1829 Lb/Ft torque and only 383C or 721F EGT on the highest bank, less on the other. Check the numbers. 4 cycles are hundreds of degrees hotter.
Pierce
That bird quote was that birds were the only coaches I had seen that bothered to have an EGT gauge oem.
Only modded engines may have benefited from EGT gauges.
I have appraised hundreds of coaches for purchase or trade in and if engines could be an issue I would have a shop dyno the motor and a oil analysis done. Never needed. No idea after 96. Was out of the biz. Had not been in a coach until 2012.
Must have been Karma as this 97 mid entry is exactly what we would have dreamed up if asked.
Sorry for the slow update, but we didn't have any data, phone, or Wifi where we went in San Isabel, Colorado.
Coolant and fluid levels were good upon check. Nothing obvious in radiator area. Not sure how to test thermostat. Coach made it up to 9200 ft without incidentt pulling the Liberty, next time I'll deploy the dinghy if I have I have another driver. If I saw temp creep up over 205ish I pulled off and let it cool down. Set throttle to 1100 rpms for a minute or two to run fans up.
Coming down, I drove using tach not speedo (new concept for me never having driven anything like this nor mountain driving)....1750 rpm did well, 185-195 until we got to Channing to Amarillo. I saw 200 on 87 S and 205, once, pulled over to rest.
Trans temps were fine going up and coming down from CO 165, saw 210ish but had been on retarder. I also deployed dinghy coming down.
Talked to Risch and he thought with outside temps it might be running a little hotter. He's noticed his own pickup running hotter lately.
I think the valuable lesson I learned, thanks to my coaches previous owner, Elliott Bray, was 1700ish rpms. This is my first class A pusher and learning to drive the tach is obviously important! Im not mechanically experienced like you gurus, and y'all are one of the reasons I love my FT!
I'll have MOT investigate when we are there for service first part of August. May be time to proactively consider new radiator and hydraulic fan. Elliott thought they were impending when I bought it three years ago. So far so good.
I am curious though, someone mentioned the p3 carrier bearing, my coach is in the age range of that being a problem, and on the rare occasion I get close to 70 mph (without a dinghy), I think it may be an issue (at PDI Risch said I should watch and plan on having Stewart-Stevenson?? Replace it ....so could this be causing the higher engine temps (remember, I'm not mechanically minded)? At my typical cruising speed 55-65 (without dinghy-63 mph or less with dinghy) it's smooth, but notice more vibration 68 mph+.
I suspect it's a combination of age, miles, and p3. 180k probably time for cooling system overhaul and time to address the p3.
Any further thoughts and suggestions (again, I'm learning only from Forum, I have no one to help teach or guide me in person, I'm not mechanically minded but trying to learn)?
1. Unless the fins are rotted out on the bottom few rows of tubes you can just have the core cleaned and new tank gaskets installed.
2. P3 bearing could be loose or failing. Only way to be for sure is to pull the tail shaft and check. If you can get to S & S in Longview they are who does trans work for FOT and know what to look for.
2b. No not unless the trans was seezing up but you would have all kinds of alarms if that was to happen to a world transmission.
Mike
One way to check the P3 is to block the coach level and insert a pry bar or large screwdriver between the balancer on the output of the trans and a secure spot. Gently pry up and note how much movement you get. It should be very slight, a few thousandths at most. More than that, better to get it tended to before it escalates.
If the P3 bearing is failing the bedroom door will vibrate in the pocket when it is open and you are driving on the interstate, will not be able to hear it from the front. Have the DW go back and listen
The motor is not running hot enough for me to spend much on it considering ambient temps and the elevation your in. Unless you see something obvious that Mike mentioned.likely when you get to flat country temps will go down.. I would be watching it same as your doing.
Agree with Dub, but I would replace the thermostat and its gasket. Inexpensive and a DYI job.
Thermostats wear metal to metal and can fail to fully open (or close).
Amarillo to home Temp was 195-200, one stretch probably 202-205. I drove a little more aggressively today at about 2000 rpms, 68-70 mph. Generator had a problem so we didn't have any air today, thus the increased speed. Plus I was experimenting with what y'all were saying.
We were on US 287 S.
1850-1950 yields 64-65
Transmission did some hunting and pecking at 68-70 in the hilly areas but temp remained pretty stable at 200.
Saw two other FTs north bound on US 287 N today too!
Temps seem high, ran south today on I-29 down to Kansas from South Dakota running into a quartering wind temps 180-185 @ 70 mph grossing 34500, outside temp middle 90s, 7.5 mpg avg.
You think the extra ten degrees in ambient air could make that big of difference?
I think I'll replace the thermostat for good measure, but do they partially fail? I thought they either failed open or closed?
How does one clean the radiator? Does the grill come off easily?
Hey you are learning what exact conditions the mechanical device you are driving will allow you go go. Whether it's right or wrong is a separate subject. Seems slightly low in capacity. So you pushed it slightly less. Exactly what I do on every drive.
It to 210 0r a half dozen times. Trans to 220 max.
36,000 pounds at 75+ Coach would go down to 60 on long medium steep grades.
I downshift a lot and run near 2,000 rpm plus a bit or retarder
By the time the grades over the temp maxes then goes down.
Not sure I would have pulled over or removed the tow.l
Not saying you were wrong. Great choices.
My experience is you are not nearly at the coaches limit.
Jhardman, yes thermostats can fail to open completely. Walking the radiator out can help, you can do it without taking the grill out. Be careful and spray straight through it to avoid Distorting the fins.
Probably, as others have suggested, some incremental improvements, cleaning radiator, new t-stats, will drop your operating temp a few degrees. And, sure, ambient air temp makes a significant difference. Basically, what I'm reading, and I'm driving same year and engine coach, you're running a 24 year old engine on the pins in high temp weather, heavily loaded, pulling a heavy toad in hilly country, with 300 hp. Can't really expect her to run cool in these conditions.
I swapped out the banjo bolt fuel overflow valve on my rig with a stock Bosch replacement and am pleasantly surprised with the increased power. Nothing monumental, but definitely more twist. Might consider this if you havent done already.
Comparisons to 320's with 50% more hp are invalid.
Smart move. All Bosch P pumps have this fuel return valve. It develops microscopic channels in the little ball and also the seat from the fuel passing by so the pressure is less inside the pump. It's easy to change and will return the internal pressure back to what it was originally.
Pierce
You can easily check for end play for the P3 bearing,put a prybar between the transmission harmonic balancer and the frame,on mine it's about a 1/2 inch gap where you put the pryer,if you get 1/8" play you have a loose bearing,many of us have had this problem,had mine retightened and inspected for 1K.You need to find a good Alison repair shop to do this,if it's caught in time and they save your bearing it's a whole lot less expensive.PS,not knocking "Risch"but what does his pickup have to do with yours running hot.
I was referring to the effect of the ambient temps.
What is the banjo bolt they're talking about, David? Where is it??
It's usually between the block and the injection pump. Normally takes a 17mm to loosen it. It will have a copper washer on each side. Here is the perfect illustration on the location and how to test it.
Check / Replace Fuel Return Overflow Valve | Cummins Diesel Engine Service (https://dieseliq.com/check-replace-fuel-return-overflow-valve)
Pierce
Will look it up but there is an aftermarket place that sells a kit to beef up the fuel pressure at idle,a few of us have done this,they also
have a fitting to install that you can put a gauge on to check fuel pressure,is good idea. Research,Tork Tools,they have the info.
If return valve is OK, the Cummins lift pump has a higher than normal problem rate. Pressure gauge will pinpoint problem. A lot of Bosch P pumps on smaller engines have the lift pump mounted on the side of the main injection pump and some even have the manual prime pump as part of the lift pump. Never seen one of these fail. Not so much on larger diesels as the lift pump is usually between the primary and secondary fuel filter and with large filters, the line routing would be more challenging.
A new stock fuel return valve will allow the injection pump to produce the full pressure/volume for full power.
Pierce
Even though our coaches have differing drive trains. The effects of how one pulls a hill are the same for any diesel pusher. We were coming back from Idaho last week and had a long grade of 5 miles and average of 6% with an 8% section. It was 90 degrees. We had lots of fluids on board and a 3,000Lb car out back. I slowed down from the posted 60MPH limit to 45-50MPH and manually put it in 4th gear. Boost never got above 17PSI (I have seen 27PSI) revs were about 1700-1800. Water temp never exceeded the upper 180's, Oil temps never exceeded 212. ^.^d
Further down the road. I had another hill to pull. But not as steep or long. I had a pickup with a loaded car trailer going pretty slow. So I used the HP of the M11 and let her rip to pass him. Turbo boost was 25PSI, Water temp went up to 200, 15-20 degrees higher than the steeper pull. The oil temp went up by 5-6 degrees. Still not close to dangerous temps. However, It was a perfect illustration of why you slow down and gear down for steep grades. Forget about those nascar dreams of passing everyone. We are in RV's, No one waved a green flag.
Replaced my stock Cummins valve (broken spring) years ago with a Tork-tec adjustable valve years ago.
https://cppdiesel.com/adjustable-p7100-overflow-valve/