6.0/3.73/6speed in mountains pulling 8000 lbs

[sportsman16]

I have 2013 suburban 2500 pulling my new Creekside 27 bh which is 8,000 loaded. First trip with this combo over Stevens pass hwy 2 in Washington state. Once the serious climbing started I was 2nd gear at 4500 rpm to hold 45 mph. Transmission temp started at 190 and hit 235 at top of pAss. TranS temp dropped quickly down the other side. I was afraid to move my foot on the gas. Any more throttle and I may have dropped to first. Any less and it would have shifted to third and speed would have lugged. I hear plenty of folks that pull heavier with this combo, how? I always read about letting these engines rev to hit max power, am I doing something wrong? Trams temp of 235 startled me a bit. Is there a better way to approach the pull up the mountain passes ?

[myredracer]

Interesting to here of other's experiences of going up Stevens Pass. First time for us last week, and first time for going up a steeper and longer climb with our current TT and F250. Our TT weighs in at about 7K lbs all loaded up.

I wasn't sure if this was steep for Wa., or how it compares to other climbs on the west coast. (The downhill run into Fort Leavenworth sure was "fun" with all the narrow, bouncy up/down, rough and twisty sections.)

I always use tow haul and I could drive at 55 mph up the pass no problems and the tranny stayed in the same gear. Still had more throttle to spare. I backed off to 50 in some spots to use less fuel. In T/H, it ran at around 4500 rpm which is good. We have a 4.10 rear end and V10 which helps. It would be nice if we had a transmission temp gauge.

It would be interesting if the OP posted their GCWR and payload & tow capacity AND TV's actual wt.

[Tystevens]

hawkeye-08 wrote:
Most of the charts are for older (30 years old) transmissions and fluids. The newer (at least 2008 and up GM) can and do run hotter. IIRC, the trans can go to 265. 235 is normal for pulling that grade. Make sure you have tow/haul selected. Keeping things clean for max airflow is a good idea.

x2. Disregard those charts. You're fine at 235*, especially for a short burst.

Nothing wrong running at 4500 rpms, either. You are right in the engine's power band.

[JEJMB]

The performance on your 3/4 Suburban is prefectly normal. I just pulled my 8000 lbs toy hauler through the CA Eastern Sierras 6% +grade @ 8000 ft (called Sherman Summit)at 80 degree outside temp. I pull with a 2007 3/4 ton Suburban (6.0/4:10 with the 6 speed). Up to 5000 ft, I can maintain ~ 50 mph at 4000 rpm. Once I hit 7000 to 8000 ft, speed drops and trans usally drop to 1st gear at the top of the mountain (Tom's Place). Trans Temp max was 225 F. Not much you can do unless you to with a Duramax or maybe install a turbo! I have to admit, the 3/4 Suburban is a beast!! Have had no issues with it. Have pulled thru the Mojave Desert at 110 deg...both the water and trans temp are solid (+210 water tempand and +200 deg on trans temp)

[hawkeye-08]

Most of the charts are for older (30 years old) transmissions and fluids. The newer (at least 2008 and up GM) can and do run hotter. IIRC, the trans can go to 265. 235 is normal for pulling that grade. Make sure you have tow/haul selected. Keeping things clean for max airflow is a good idea.

[bighatnohorse]

The tranny is fine. It just shortened the transmission fluid life.
Change the tranny fluid soon.
Charts on transmission temperature and fluid life.

[Bull_Rider]

We've towed over Stevens Pass and Blewett Pass dozens of times, with both gassers and diesel.

I always would lock in second gear, and hold at about 4k thousand with the gasser. I wasn't concerned with the speed. Just let the engine breath and do its thing. If the slope diminished, I would ease up on the gas to maintain the 4k on the tach. Until I could upshift without over taxing the engine.

235 on the tranny temp. would be OK for short pulls. A synthetic tranny fluid might be better with hotter temps.

[ksss]

I would also check your coolers, I was having problems with my LBZ cooling and finally the dealer pulled the the radiator out along with the intercooler and tranny cooler. I had a ton of debris caught between the stacks. Took it out last weekend pulling hard over some good sized passes and it ran just as it should. Totally fixed the problem.

When your towing up grades like that don't draft big rigs as someone suggested. It cut cuts your airflow to your radiator and will cause you to run hotter than you need to. It saves having to cut the wind yourself but you need the airflow over the radiator and tranny cooler.

I personally have never seen tranny temps that high and I pull almost twice as much weight over 7500 foot passes regularly. 210 is the highest I can recall seeing. I would consider switching to Amsoil tranny fluid (or some other high quality synthetic) or make sure you service your tranny under the sever service recommendations.

[Mr_Beebo]

The elevation is a big issue. I can tell you that my 6.0 6 speed with 4.10 gear pulls fine up to 5500'. Haven't been higher than that. I have pulled loads of 12k and have not has issue. With an 8-10% grade I can hold 55 mph much easier than I can with my old 5.3 half ton. Usually in 4th and sometimes in 3rd. Our current camper is about 6k unloaded.

[blt2ski]

Sounds like a normal trip across Stevens. THat is one of the steeper pass;s here in Wa st. Tiger south of issaquah is probably one of the steeper ones, as is HWY 20 across the N cascades. You would have been doing probably 50-55 on I90 except the last part after exit 52, that last 200 yds or so is the steepest part of the climb going east any how. Hyak to the summit going west is also the steepest part. Not as steep as Stevens.

you also have to remember, with a non forced induction motor, at 4000' on stevens, you are down about 8-12% of your HP vs here at sound level where you are not normally much over 500'. North Bend is only 700 or so feet.

Marty

[texasclarks]

I pull about the same weight here in WV but with an older Sub2500 with 8.1L and 4-speed tranny. I know my truck CAN pull heavier and still has throttle response left, but...I prefer to go slower...and there are a lot of hills/mountain passes in WV.

[azwildcat99]

sportsman16 wrote:
...As I watched trans temp rise and didn't think I had much throttle left, I wondered how folks pull 10k or more with this combo?

I wonder the same, as there are those that claim they tow this heavy and heavier with the old 4sp combo. I have about the same size TT as you and have thought about getting into a Suburban with this or even the older combo but worried about climbing the hills.

Anyone out there with real experience towing a larger weight with this engine as I didn't see any posts for someone else with this or the older combo?

Thanks for the post.

-Tom

[larry_barnhart]

sportsman16 wrote:
Sounds like I shouldn't worry. I tow in m5 with tow/haul on interstate and flat ground. Sometimes drop to m4 in rolling terrain. This was first pull up pass with heavier trailer. I was in m3 but when tranny dropped to 2nd I held throttle steady and maintained 45 mph. Maybe next time I will hold at 40. As I watched trans temp rise and didn't think I had much throttle left, I wondered how folks pull 10k or more with this combo?

No matter what you drive your last comment was the best for your truck and gives more time to enjoy the scenery.

chevman

[sportsman16]

Sounds like I shouldn't worry. I tow in m5 with tow/haul on interstate and flat ground. Sometimes drop to m4 in rolling terrain. This was first pull up pass with heavier trailer. I was in m3 but when tranny dropped to 2nd I held throttle steady and maintained 45 mph. Maybe next time I will hold at 40. As I watched trans temp rise and didn't think I had much throttle left, I wondered how folks pull 10k or more with this combo?

[ib516]

Sounds normal to me. Trans temp that high for short duration is not a problem either.

[kw_00]

Well your truck was not struggling, your gas engine as at its peak TQ RPM. I have seen 45 in second gear on my 02 truck, normal given the grade. Even diesels give up speed up steep grades... Yep been there with the 01 DMax. Don't sweat the tranny temperature, I expect to see that spike during times of steep pulls. All in all everything appears normal, 4:10 would have given u some extra edge but not that much. Your 6.0/ 6 speeds is one of the best combos out there.