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Burker99 · 07-22-2020, 11:40 AM

A while back I posted about my upcoming trip to Colorado and Wyoming. Well, I am sitting in Gunnison after coming over Monarch pass. We have traveled down to Ouray and spent time in that area and are now getting ready to go back over the pass.

This post is to tell you my experience and to ask a little more advise. My RV is a 36’ 2001 Monaco Knight with a Cummins 5.9 and an Allison 300 trany.

The pass was very interesting adventure. My RV will normally run at about 180* at about 60 MPH on flat ground. Coming over the pass I had to gear down to 3rd gear and about 22-2300 RPM and about 30-35 MPH. My temperature rose to about 205*. The highest I have ever seen it. After reaching the summit it went down even below 180 as I used very little power and the exhaust brake that kept me in 2nd gear and RPM around 2400. I stabbed the breaks several times to keep my speed and RPM low.

One the way to Ouray I went over 2 other long climbs that slowed me to similar gear (3rd) and about 35 MPH and temp about 205*. The same thing happened on the way back. Once I am on level ground everything returns to normal. I did have to stay out of 6th gear a lot and some times went to 4th on some hills.

So, my questions are, does this sound normal for my Rv. I am running heavy and dolly towing a car. I am probably around 27-28000 lbs total. The temp that high is a bit concerning. I spoke to Cummins and was told I can go to 212* before any problems. It was a bit closer to that than I would have liked but the temp did not seem to get above about 205*. I only have a dash temperature gauge and I do wonder about its accuracy.

Advise and comments are welcome. I would like to here form anyone who has a similar set up as me.

I am planning to head north from Buena Vista to Wyoming and will take any help on roads and passed on that route.

Thank you,
Phil

96 Wideglide · 07-22-2020, 11:53 AM

Sounds perfectly normal to me.

jacwjames · 07-22-2020, 12:03 PM

What was the ambient temperature outside, this could result in higher running temps if really hot out.

My coach relies an a thermovalve to control the fan speed, my manual says at 199F the fan will run wide open. I've seen my temp to climb a little over 200F. I have a Silverleaf that will alarm if temp gets too high. We were climbing a long gradual grade in Albuquerque NM ~5 years ago when I got the alarm, downshifted to get RPM's up temps went back down.

Only thing I'd suggest is to clean your I believe you have a rear radiator & CAC assembly. Any restriction of airflow will cause higher temps.

Burker99 · 07-22-2020, 12:06 PM

Just cleaned the radiator before this trip

Milford 47 · 07-22-2020, 12:08 PM

Sounds good for your engine

I usually follow trucks up and down so never at full throttle going up

Typically stop on top and take a break, coffee or coca, enjoy the scenery unless it is snowing

Nice big area to park

At Buena Vista take in a ghost town if you enjoy that

Burker99 · 07-22-2020, 12:08 PM

It is pretty hot out probably 80 when I went over the pass. Temps in the area around 90

RVThere · 07-22-2020, 12:21 PM

I was having the same problems with my 2007 Winn Tour with a rear radiator.

I would diligently clean the radiator with compressed air and then with a hose. Thought everything was good.

Eventually (about 90,000 miles) it was running hot more consistently. (195 on flat road). Brought it into my mechanic who removed the radiator and said 'it was like a blackboard' facing the engine. Intercooler was gunked up too.

So, your radiator etc. may be blocked/dirty in areas you can't clean.

You can buy a wireless endoscope that links to your smartphone for about $40. Has lighted end. You can stick that up behind the radiator and get a really good look at the fins.

FL420 · 07-22-2020, 01:10 PM

Those numbers are very close to those on my 2005 Knight with the 8.3l Cummins ISC. I also pull a toad on a dolly but, even though it's a no-no, I have a motorcycle mounted behind the rear radiator which seems to make no discernable difference in coolant or transmission temperatures.
Your mountain driving techniques sound pretty good. Driving with the dash heat and fan on full high also help a little bit.
If a ScanGaugeD is compatible with your engine (call and ask them) I would very highly recommend you get one. Best thing I've ever bought for my coach.
I thought I had overheating problems but found out my analog coolant temperature gauge was reading 10+° too high. It also helped me diagnose a slightly loose clamp on my overflow tank causing a low coolant warning. I have only had to detach the toad once and have the DW follow me the last mile or two up the mountain due to high coolant temperature.
If you're ever driving west from the Midwest to the Front Range of Colorado you should monitor your temps as it's a long steady hours long climb from about 1000'MSL to about 5500-6500'MSL. The drive looks and feels level but it's not.

Burker99 · 07-22-2020, 01:16 PM

Did that last year on l80 3000 elevation gain from North Platte to cheyanne

IMDiesel · 07-22-2020, 01:23 PM

Quote:

Originally Posted by 96 Wideglide

Sounds perfectly normal to me.

I agree. My "05" ISB 5.9 also shows a working temperature rise when climbing a grade. I see no problem. Especially since you cleaned the radiator recently.

Spk64 · 07-22-2020, 01:25 PM

Looks somewhat normal.
For first timers in the mountains those “hills” can look deceiving and you start to wonder why am I losing power and slowing down. Then you see the long line of tractor trailers all doing the same.
Monarch pass is a long grade my first and only time through going East to West was without a working engine brake. Going down was an experience. Made use of a pull over to let the brakes cool down some as I know they were getting a workout.
Past couple trips have been across 70 West to East and the downhills are easy with the engine brake but still slow down and get in line on those climbs back up. Downshifting to keep RPMs up and temps in check.

momdoc · 07-22-2020, 08:58 PM

Sounds normal to me.

We will be doing that run (west to east) in a month or so. Hopefully with NO snow.

SargeW · 07-22-2020, 09:22 PM

I don't have your set up now, but I did have. Your experience and technique were spot on. The key is not to over drive, and let the engine and trans do what they were built to do. Keep the RPM's up going up hill, and the speed down coming down the other side.

Just as an FYI, my current set up is over 43,000 pounds. I am 40' long plus a Jeep four down. My hill climbing numbers look a lot like yours, but I am pulling it with a Cummins ISL 450HP. The manufacturers build these rigs to perform in a parameter to handle the expected weights and driving conditions. The associated parts are as well. For your size of coach and weight, you are right in the ball park.

**Lt Dan** · 07-22-2020, 09:33 PM

I have been over Monarch and almost every pass in Colorado more than once and in Ouray now. Your temperature range is normal. Mine will run about 180-85 until I start climbing then the temps go up. At about 210, the fan clutch kicks into high and the temps start dropping to about 190 then start up again if we are still climbing. If you are able to climb Monarch at 35 that's not bad. Keeping the RPMs in that range is your best bet. My first time over it in a gas coach it was 20mph with my foot to the floor. At some point you might want to get a ScanGauge D which will show you exact temperatures. '

Depending on where you are going in Wyoming, you might want to go north on 550 to Grand Junction, then I70 to Rifle then take Hwy 13 north.