Driving in the mountains

[JPaul]

I just drove from Salt Lake, Utah to Colorado Springs, Colorado and took I70, which for those that don't know that route it has a fair number of long, steep climbs (the climb out of Vail is the worst I think). With the 3.7L it really, really, REALLY struggles to make it up the grades, especially with all of the family, gear, 33 inch Duratracs, and roof rack. If I try to keep at 65 mph on the steeper grades it will downshift and sit around 5200 rpm or so. If I don't want it to do that I have to drop down to around 50 mph and it either stays in 4th but struggles to maintain that speed or it downshifts and sits around 4000 rpm.

My question is, how bad is it to try to maintain the 65 mph speed and let it be in that higher rpm range for a long climb? I worry that it will wreck the engine. It's not something I do every week, I only come out to Colorado maybe once a year or so. I also just changed all of my fluids.

This trip I ended up going with the slower speed option, but it sucked having everyone else passing me and barely overtaking the semis making the same climb. Last year when I made the same trip I was using cruise control set to 65 and would let it run in the higher rpm 's but I was seeing wild swings in the coolant temperature as the thermostat would open and cold coolant would rush into the engine (it was a lot colder this time last year so the fan and air speed was cooling off the coolant very quickly while it was in the radiator).

I'm wondering what everyone else's habits are with driving at highway speeds in the mountains with the 5 cylinder H3's.

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[Neo]

the 3.5 is even worse, when i used to drive it back and forth from SoCal to Moab over the Utah passes i would set the cruise at 60 but it would still sound and feel like a Cessna on takeoff. there's no cure drive it till it explodes or the head warps :wink: I'm kidding. never had the heat issue, but most of my runs were in December with snow on the ground from here to St George...

 

[4speedfunk]

Totally normal. The two choices are exactly what you describe....third gear & let r eat...or fourth gear and hazard lights in the slow lane.

Of course there are a few more options but, none cheap or easy...re-gear, motor swap, or get a truck made for such road trips (2500 Duramax).


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[f5moab]

I've done it a few times.:horns:
Try it with a 3500 pound trailer on the rear end.
I did have a trans cooler installed, and eventually got a Silverado to pull the trailer. But before that, I pulled the trailer up and down many mountains in UT/ID/MT and WY.
And if you think Vail pass is bad at 7%, go try Teton Pass at 10% grade (without a trailer), the rattlesnakes will pass you.:giggle:

Pulling the trailer up Teton pass with the Silverado was not problem and glad I never tried the H3 and the trailer up the same pass. It might have taken a day or two.

 

[Woodtick]

I never use cruise while towing or in steep grades. Simply drop down to 55 mph and call it a day. You could get the SRT Jeep for road trips?

 

[alrock]

Agreed, I rarely use the cruise on the H3 if there are any hills involved. You need to build up speed at the bottom of hills, get as far up as you can with that extra momentum. If you can lose the roof rack on those trips, that will help. And, as already stated, accept 55 mph for that portion of the trip if necessary.

My H3 drinks oil, I think through blowback, during these high rev climbs (also when going high rev in low range off road).

 

[DJinCO]

My best advice is to not travel on I-70.

 

[3Hummers]

I drive by the temp gauge.

 

[alrock]

I've had to do that in the H3 on some hills and hotter days.

 

[JPaul]

I could have taken I80 but the wind was supposed to be super bad on my trip out. I actually averaged about 14mpg coming out to Colorado on I70 which is better than I expected. I wish GM had at least given the H3 a 6 speed transmission instead of the 4 speed, then the hills wouldn't be an issue.

Thanks for the input guys, I'll probably just stick with taking it slow up the steep grades and keeping RPM's lower. I think the sustained high RPM's might've been what led to the rod bearing going out eventually on my previous engine.

I'm not sure what my long term plans are going to be with the H3, but either a V8 swap or a swap for one that already has a V8 is likely in the cards. Fortunately until then I don't make these kinds of trips very often.

 

[Neo]

My H3 hasn't left Moab in the last 7 years :giggle: but it has been on the 70 between Crescent Jct. and Green River

 

[f5moab]

My H3 hasn't left Moab in the last 7 years :giggle: but it has been on the 70 between Crescent Jct. and Green River

Hard to believe that it was seven years ago that we did Black Bear pass (Aug 2009), and Capital Reef, same year....

 

[Neo]

that was a fun trip, thanks for digging up those pix... hard to believe it was that long ago...:gaah:

 

[Neo]

Not long after that i got the H1... Wow!!! Dec 09 Desert and I went ice crushing down Kane Creek... and i had the truck for awhile then

 

[SuperBuickGuy]

fun stuff. GM validates their motors before they ever hit production. Validation is this. The engine is put under load on a dyno then goes between 70% and 100% hp for 600 hours. Basically that means it runs between 70% of red line and red line for 600 hours straight. I think you going over a mountain pass isn't really even much of a challenge for it. Rumor has it they do this to 800 motors.... yeah, 800. The newest LT powerplant has the equivalent of 12.5 million miles of testing before they ever got put in the wild.... as I said, I think you're okay :thumbs::giggle:

 

[f5moab]

Don't forget the 50K test at Milford and the old Desert Proving grounds for emissions and CAFE. And almost all vehicles are on long road trips out west to do the mountain passes, hot desert climate and especially Hoover dam. New engines can be road tested in older test mules. For example, Saturn used small cars for engine/transmission mules, similar in size prior to the vehicle being produced; been there done that, and it was fun; except for the cold weather testing in Kapuskasing Canada where the avg temp in Jan is around 10 degrees during the day.

I remember the road testing of the 4.5L Duramax that was stuffed into 2007 trucks and driven for thousands of miles throughout the USA; up and down mountains, in the desert and also up in Canada based out of Kapuskasing. Then GM dropped the engine due to the economy.

 

[f5moab]

that was a fun trip, thanks for digging up those pix... hard to believe it was that long ago...:gaah:

We did a lot of caravaning back in those days. Remember that was the trip (capital reef) where Hunner lost his Dingy.:giggle:

That's Hunner in the lead and you behind when going through the Bentonite hills in Cathedral valley.

Then later connecting up with Alec and the tree counting hippies begging for beer and ribs.:gaah:

 

[Mr_Rich]

fun stuff. GM validates their motors before they ever hit production. Validation is this. The engine is put under load on a dyno then goes between 70% and 100% hp for 600 hours. Basically that means it runs between 70% of red line and red line for 600 hours straight. I think you going over a mountain pass isn't really even much of a challenge for it. Rumor has it they do this to 800 motors.... yeah, 800. The newest LT powerplant has the equivalent of 12.5 million miles of testing before they ever got put in the wild.... as I said, I think you're okay :thumbs::giggle:

I have a book on the shelf for the GM 2.8L V6 and I think I remember that they used to pull these engines out of a freezer and run them to redline to find the weaknesses in those engines. I actually like those engines but they definitely weren't truck engines.

 

[Mr_Rich]

In '86 I owned a Jeep Comanche pickup with a 2.8L/ 5M drivetrain and I think is had 115 HP. The engine ran with a feedback carb; no fuel injection yet in those days. I loved that truck but it was so under-powered it wasn't even funny. Any kind of load in back and I had to rev it out in third gear @45-50 MPH going up steep grades. Once the engine was revving I could run it @80 MPH (I was younger in those days). I keep this in context with comparison of my 3T which is a heavier truck and I can load the back end with 500 lbs. (like an engine) and drive up steep grades at the speed limit in fourth gear (with my 5M).

 

[GreatDaneHummer]

I did that very same route this year with 35" tires, the 3.7 and a good 1000 lbs of gear / camping equipment / wedding stuff. I ended up at 40mph in 3rd gear crawling my way up with hazard lights on the entire time. This is with the computer tune, air doc, full tune up and larger throttle body / full exhaust. After all of it when I got home 2 weeks later to Chicago my trans went out even with a cooler. I would just avoid it or trailer it next time.

 

[4speedfunk]

Yeah but don't forget....you were also front wheel drive!

:giggle:

 

[JPaul]

I kept an eye on everything coming back to observe how it performed. It really does do OK except for those really steep grades, and this time coming back I had my cargo bag up in the roof basket with all of our luggage in it since I was also hauling back a dishwasher and some kitchen stuff my mom gave me from her commercial kitchen she recently shut down. I can stay around 50-55 mph in 3rd gear or whatever it sat in at around 4200 RPM and be ok. It still adds extra wear, but not near as much as 5500 RPM. A catch can is still on my to-do list though.

I know when I was hauling the Boy Scout's trailer earlier this year up to our LDS ward's campout in the mountains I didn't do too bad even though that trailer weighs quite a bit, though that was at lower speeds anyway due to the speed limit being lower.

Thanks for all of the comments everyone, I learned a lot!

 

[GreatDaneHummer]

Yeah but don't forget....you were also front wheel drive!

:giggle:

I'm not sure if I broke the rear end out in Colorado or if it was just on this last trip to the Cliffs. I only notice 1 mpg difference now that it is running 4 wheel drive again.

 

[2010H3TAlpha]

After graduating from a 2.7L I4 4x4 ext cab Tacoma to a V8 Grand Cherokee 10 years ago, I know I'll never go back to anything smaller unless it is using forced induction, i.e. Ecoboost. Truth be told, the 5.3 is even a little underpwered for my taste, especially with 35s. My friends' Hemi Rams and Ecoboost F150s make me green with envy and wishing for the 6.2L & 6L80, but I've always loved big power no matter what the vehicle. And the H3T is our only vehicle at the moment while we throw all our money at our mortgage so one day when I get another muscle car, that will definitely help address my hp addiction. Plus, my friends' trucks can't "walk" up just about any trail like my H3T can so I'll stay happy for now. And driving something this unique/rare is also very rewarding for me.