Tips for descending a steep grade

[TX-Trek]

We had a torque converter failure in Colorado as well, back in 2014. It was on the earlier 4-speed tranny, and we were not as fortunate as you about finding someone to repair it and had to nurse it home some 2500 miles.

Oh no! I'm sorry to hear that .
For the record it was A-1 Automatics and Towing in Trinidad CO. Not only did they fix it with good parts, they also wrestled it out without being able to remove the crossmember. Thank you RT and your stupid waste and water tank placement. I even told them cut the crossmember and we'd weld it back up, but they managed. In the meantime, we found a little motel, got a used car rental, hiked the area and met some great folks who went out of their way for us. Was quite the adventure.

 

[dicktill]

Oh no! I'm sorry to hear that .
For the record it was A-1 Automatics and Towing in Trinidad CO. Not only did they fix it with good parts, they also wrestled it out without being able to remove the crossmember. Thank you RT and your stupid waste and water tank placement. I even told them cut the crossmember and we'd weld it back up, but they managed. In the meantime, we found a little motel, got a used car rental, hiked the area and met some great folks who went out of their way for us. Was quite the adventure.

Don't want to totally derail this thread so I'll start this message with "yes, we had braking troubles when the Roadtrek was new but fixed that with ventilated rotors and semi-metallic pads". Will also mention that I tried ventilated rotors on all four corners and both rears cracked, so back to solid rotors there.

As for the tranny problem at the time Chevy was having massive recalls (air bags?) and the dealer wouldn't even take a look at it for three weeks. Nursed it home by heading south first through New Mexico to minimize the hills, starting ever-so-gently in 2nd gear, manually easing it into 3rd at maybe 15 mph, and easing it into 4th at maybe 30 mph. Limited top speed to 60 mph at the most. Long, nail-biting drive.

 

[ChristyCappello]

I've tried to google ideas for descending a steep grade in a heavy van, but all I find is things on semi's with jake brakes. Not quite applicable to our 9200lb 08C210P Roadtrek.

Since I live where it's pretty flat and we'll be traversing some grades on our trip coming up, I'm just inquiring on how others, who may live in mountainous areas, have descended grades, such as some of the grades on I-70 heading west out of Denver. We're not going that route and will likely be on 2 lanes, but just looking for a couple tips. I'm aware of dropping a gear or two and not riding the brakes, but looking for specifics on what others have done successfully, such as slow to 35 drop to 2nd gear and head down, engage the two/haul mode and use 3rd gear, etc. If one drops to 2nd gear, will that typically hold the vehicle from running away without using the brakes (that's how it's supposed to be done in a semi with the jake brake on and running lower gear), these types of ideas. I've hauled 7000lb loads thru the Ozarks with my old truck in the past, but those are baby hills compared to what we're likely to run into, and my old truck didn't have a tow/haul mode on it either. It was just a beefed up Chevy half ton, and I'm sure that what I did probably could have been done a lot better. Just looking for people who've done this a lot more than me. I will say that the camper feels nothing like the old truck and trailer.

Thanks.

I like to tell you what happened to me going down a mountain in Cal. When I stopped my brakes were smoking. I googled on what to do & the information was to let them cool off for 30 min & when descending to put the transmission in second gear& disabled the overdrive setting. I also posted on a FB group for Roadtrek & that was their suggestion. So when I’m going down a mountain I will put it in 2nd gear & turn off the overdrive. I never had an issue with smoking brakes again.

 

[TX-Trek]

Sorry for long winded post....
Yesterday it was about ascending 6% grade on Hwy 50 out of Pueblo to Gunnison CO. There's a pass in there that I think is at 8k ft?
Anyway, its a long uphill trip and I have to say our 210 struggled. 6.0/6spd.
I know engine power can be reduced at heights, maybe I asked for too much. Tried to keep 45 going up - running at 3k rpm in lower gear for a long time was rough. Engine temp stayed normal but I knew the transmission was getting hot. I stopped and idle it to keep fluid circulating thru radiator and cooler. I had it in manual mode going up but it will find its own downshift points. I noticed that it didn't necessarily shift up at grade moderation as I expected.
Reading up on the 6spd adaptive shifting, the TCM will sometimes delay shifts if transmission temp is higher.
Anyway, the downhill was fine and after reaching relatively level roads it acted normally. Fluid level and condition was fine.
I have a new Delco fuel pump with me, theres a small evap leak at the pump fitting, so I got the pump anticipating changing it at some point.
I mention the pump because I thought about fuel pressure under heavy load yesterday. The van really struggled on the steeper grades, but gets about 16 mpg in all other conditions. That tells me its in generally good function.
I've got a bidirectional scantool plus a standard scantool with me, but it seems that this 2010 model doesnt have a fuel pressure PID I can see... so its all a guess unless i pull the doghouse to get a gauge on the fuel rail.
Anyway, we're moving thru CO and will try to look for moderate grades going into UT out of Grand Junction. I know this thread was about descending but I was disappointed in the uphill part of it.
Colorado is beautiful!

 

[booster]

Tx-Trek. Do you have the trans temp readout on a Scangauge or other method. With a 6 speed, I would expect the converter to do be locked at 3K but they do it by speed and have a bunch of other overrides so can't be positive. I have posted the shift points and lockup points, but in MPH, on one of trans overheating threads and may still have the 6sp PCM program download I got when researching back then. The six speeds, from the user reports I have seen (mostly in pickups) indicate the 6sp is probably temp controlled and at a high temp of around 210*. Our 4 speed goes into limp mode at 240* so if yours is there you don't have much overheat window.

My best guess was that you might have been in conditions that got you into a load generated unlocking of the converter is you were getting hot. The fact that the engine temp didn't rise might indicate you weren't getting overly hot in the trans or it would have pushed the radiator temp up like if does in the 4 speeds. Those conditions would normally be near 100% throttle position and near 100% load. You would have the 6.0 with variable valve timing and higher hp and torque than the 4 speeds version 6.0 like we have, but the variable valve timing version actually has lower torque at low rpms compared to fixed timing ones. I have the curves around here somewhere as I don't know where they would be at 3Krpm.

My guess it that if you had a fuel delivery issue under that much load, you probably would get a fault code of some sort as they trigger them pretty easily. We got bad high altitude gas in Denver once and we lost a lot of power once we went lower as it reduced the power do to knock. We haven't seen major power reduction at 8K that I noticed, but by 10K it got quite noticeable.

 

[booster]

Tx-Trek.

Take a look at this post that I mentioned above. It may give you some insight of what the trans and converter were doing under the conditions you were at when you got worried about heat.

Teach your old Chevy new tricks?

This time of year gives some time to go a bit deeper into some of the oddities of our vans, and this is another step into trying to determine why the 4 speed Chevies get hot, primarily transmissions, on long climbs. Lots of things make incremental improvements, like big coolers, two core...

www.classbforum.com

 

[TX-Trek]

Thank you! Yes I can read temps on my scantool, but didn't have it plugged in yesterday.

So today was a much better story and I think to be honest operator error may have been a factor yesterday.
Not as long steep uphills today but still had the descents. Yesterday I had it in manual selection, primarily for the descents. I did not have it in tow/haul mode. Dummy.

Today I used tow/haul and it went up the grades much better, no crazy rpms or transmission flogging its way up. Now it felt like adequate engine power and I didn't need to floor it. I think this mode, as stated in the manual, significantly changes the shift pattern, converter lockup etc. Much better experience. Subjective - the engine and transmission felt like one locked-in unit today as opposed to previous day engine thrash with transmission sort of along for the ride.

On the descents, I put it into manual mode so I could select the downshift. The tow mode will downshift as you hit the brake, but it often went 2 shifts lower which was fairly harsh. I did control the speed fine, no problem at all. By using manual I could just nip it down one gear at a time as needed. Very controllable, no cooked brakes. That frequently harder braking but not constant braking works well.

For average CO rolling terrain the tow/haul mode works very well. My lesson is read the manual even if you've already read it. Overall it was a good drive today.

I agree with you that low fuel pressure would probably trigger a CEL.

Thanks for the link too, its pretty clear on the converter operation. I think that the transmission got hot but not overheated yesterday. I did check this morning just to verify, fluid looks good and to correct level.

Oh, meant to mention that the 6.0, unlike the 5.3, does not have AFM. Our Silverado 5.3 with AFM has had a Range Technologies AFM disable plugged in for years.

 

[booster]

Thank you! Yes I can read temps on my scantool, but didn't have it plugged in yesterday.

So today was a much better story and I think to be honest operator error may have been a factor yesterday.
Not as long steep uphills today but still had the descents. Yesterday I had it in manual selection, primarily for the descents. I did not have it in tow/haul mode. Dummy.

Today I used tow/haul and it went up the grades much better, no crazy rpms or transmission flogging its way up. Now it felt like adequate engine power and I didn't need to floor it. I think this mode, as stated in the manual, significantly changes the shift pattern, converter lockup etc. Much better experience. Subjective - the engine and transmission felt like one locked-in unit today as opposed to previous day engine thrash with transmission sort of along for the ride.

On the descents, I put it into manual mode so I could select the downshift. The tow mode will downshift as you hit the brake, but it often went 2 shifts lower which was fairly harsh. I did control the speed fine, no problem at all. By using manual I could just nip it down one gear at a time as needed. Very controllable, no cooked brakes. That frequently harder braking but not constant braking works well.

For average CO rolling terrain the tow/haul mode works very well. My lesson is read the manual even if you've already read it. Overall it was a good drive today.

I agree with you that low fuel pressure would probably trigger a CEL.

Thanks for the link too, its pretty clear on the converter operation. I think that the transmission got hot but not overheated yesterday. I did check this morning just to verify, fluid looks good and to correct level.

Oh, meant to mention that the 6.0, unlike the 5.3, does not have AFM. Our Silverado 5.3 with AFM has had a Range Technologies AFM disable plugged in for years.

Glad you got it sorted out, always good to hear about great outcomes.

You are lucky and have dynamic braking that does that downshift stuff. The 4 speeds like ours only disengage the converter when you close the throttle, just the opposite of what you want to do on big descents.

Exactly, the 5.3 has the AFM that disables cylinders, I think, but the 6.0 doesn't. What I was referring to was the variable valve timing that changes the camshaft advance based on load and rpm, which your model should have I thing even though it is the first year for the updates. It allows them to design the engines for more higher rpm power without total killing the low rpm power.

 

[TX-Trek]

Ah, yes for the cam timing. Sorry I thought you were referencing AFM.

Thats a good way to refer to the dynamic braking with tow/haul mode, as soon as the brake is depressed it downshifts.

Although I do feel a bit silly for calling it a van problem when I should have known better, I thought best to post. Especially for those that have the 6 spd with tow and manual modes, once I got it straight, it went well.

Thanks for your help too!

 

[youngnretired]

I have enjoyed the conversation regarding going up and down hills, and don't think the thread has been hijacked. Also learned a lot thru what's being posted.

We're currently in Missouri on our route 66 adventure and with the "small" hills they have around here, I learned that the rear rims seem to get much hotter than the front on our 08C210P. I believe that this may be due to the fact that the rears are set back from the outside of the body more than the front and likely lower cooling airflow to the wheels? I don't think we have a problem and don't know if this is normal, but just something I noticed. Both rears are about the same temperature, so one's not hotter than the other, so it's not a specific equipment issue on only a side.

 

[TX-Trek]

I know that hub temps on ours run hotter in the back than the front too. But nothing unmanageable. I've got a temp gun with me, I'll try to remember to check today. I think temp difference is due to the rear axle carrying more weight, plus the heat of the gearset carrying into the axles.
This was our full travel weight, as you can see, that 6k rated axle is loaded. 2k weight bias to the rear - I run 80/65 psi rear/front that works well.

If you get the chance, you can use an truck stop CAT scale to measure your front and rear weights. It was about $12 when I did it.

I've done front/rear suspension work (thanks Booster) that has helped tremendously as well:

Our Tubby Roadtrek 210 – A Long Post on Suspension Upgrades

This is about the suspension changes to our 2010 210P on the Express 3500 chassis. Current mileage 76k. Stock AR wheels and stock LT245/75R16 tires. It’s no secret that this era of vans are overloaded. I decided to improve the suspension on ours based on the excellent information in this forum...

www.classbforum.com

Also, using a high quality gear lube I think can help, as its less prone to breakdown. It's key to lube and cool those rear axle bearings, as they aren't full floater type. In my case I use Redline, after about 10k miles it looks new. However as PM, I'm going to change it after this trip along with oil/trans.

Edit - I checked hub temps at a gas stop today. Ambient air temp 73, ran at 65-70 mph. Actually not directly at the hub, measured on the wheel where bolted to the hub. But I think that would still show a trend on temps.
Front 84d, rear 98d. Assuming the hub would be hotter before wheel rim dissipated heat, I think it's still an acceptable heat level.

 

[TX-Trek]

Just an update about using the tow mode and manual selection on our 6 speed.
We've been up and down a number of steep grades and using the tow mode for ascending has been great. No problems with power delivery, or crazy strained downshifting rpms. Of course I'm not trying to race up grades, but its not bogging at all, just holding moderate speeds
Downhill, using the manual selection works better than the tow mode, which tends to downshift "dynamically" as braking is increased, dropping down more than a gear. This can cause some over revving which I want to avoid. By combining braking with manually selected lower gearing, downhills are very controllable, no burned brakes.
This combination has worked very well for us as we continue down the road.

 

[TX-Trek]

Our 4 week road trip is done. Back home safe and sound. 4603 miles, averaged 16.6 mpg which includes travels through CO, UT, ID mountain ranges as well as "normal" rolling terrain.
The van ran like a champ, I'd use tow mode literally for days on end. Fluid looks fine, about 9k miles since rebuild, but I'll do a transmission service regardless, as I want to see in the pan.