Duramax/Allison downshift?

[1976gmc20]

This morning my daughter called from Nebraska on her way west with a gooseneck and horses. She said her truck is slow to downshift on moderate hills on the interstate, like it's staying in overdrive.

It only has D 3 2 1 so Drive apparently includes overdrive, and no way to manually get it down to direct. She said she has to totally mash the pedal to get it to shift down a gear.

So my question is there "kickdown cable" on these or is it all electric?

Also, the tow/haul button doesn't seem to be having any effect, even though the dash indicator comes on. I told her to manually shift it down going over Monarch Pass, when she starts getting down under 50 mph.

(2002 K2500HD)

[hatzie]

It's all electronic including the go pedal.
Hit the tow-haul button. The shifting behaviour changes.
I often put the shifter in 3 when I'm towing something heavy to keep my 4L80E from hunting or lugging the engine by staying in 4th gear when it really should downshift.

If she figures it should be in a lower gear and it isn't going there pull the lever down a notch and drive.

[1976gmc20]

Originally Posted by hatzie

It's all electronic including the go pedal.
Hit the tow-haul button. The shifting behaviour changes.
I often put the shifter in 3 when I'm towing something heavy to keep my 4L80E from hunting or lugging the engine by staying in 4th gear when it really should downshift.

If she figures it should be in a lower gear and it isn't going there pull the lever down a notch and drive.

Okay, thanks

She says she had it in tow/haul mode. The problem seems to be moderate hills on the interstate. "Drive" seems to be either direct or overdrive without any way to control that. Shifting down to 3 would probably be too slow or too much of a shock going down two gears at a time.

But then I'm not there driving it so I don't really know ??? I drove it to Billings and back empty to get some service done and it was fine.

On our old Suburban 350/700r4 of course I just ran in D instead of O when towing. I did find it would slow way down on hills and then shift down and speed up and then shift up and slow down again, so I would just pull it down to 2 at about 45 mph and just go comfortably up the hill without much throttle. In the mountains so that was plenty fast enough.

[1976gmc20]

She's just west of Denver right now and apparently leaking ATF from the cooler or cooler lines. It blew back on the exhaust and started smoking.

And I had the transmission cooler lines replaced by the Chevy dealer!

Edit: well, apparently it was engine coolant leaking and not ATF. She's unloading the horses somewhere and getting it to a dealer.

Edit #2: She got somebody from the west slope to come over and get her and the trailer and the animals, and leaving the pickup at an independent shop to be be fixed. Hopefully it's just radiator or heater hoses but they say that they are hard to get to. More buck$ (hers, this time)

[1976gmc20]

Well, I'm probably just talking into the void right now - but ...

The problem was the "coolant bypass hose" they said the clamp was loose and they don't know how in the world she made it from Montana to Michigan, and then from Michigan to Denver pulling a 10K# gooseneck without it leaking before yesterday!

$340 to repair a loose hose clamp

Would removing or loosening this hose be something a shop would do when draining/flushing/refilling the coolant ???

[fun in dirt]

Originally Posted by 1976gmc20

Well, I'm probably just talking into the void right now - but ...

The problem was the "coolant bypass hose" they said the clamp was loose and they don't know how in the world she made it from Montana to Michigan, and then from Michigan to Denver pulling a 10K# gooseneck without it leaking before yesterday!

$340 to repair a loose hose clamp

Would removing or loosening this hose be something a shop would do when draining/flushing/refilling the coolant ???

You're not talking into a void friend, I hear ya
Over the phone diagnostics & on the road repairs are things that cause major headaches & wallet hurt sometimes. Sounds like the good Lord & good luck is on her side though!

[hatzie]

Originally Posted by 1976gmc20

Well, I'm probably just talking into the void right now - but ...

The problem was the "coolant bypass hose" they said the clamp was loose and they don't know how in the world she made it from Montana to Michigan, and then from Michigan to Denver pulling a 10K# gooseneck without it leaking before yesterday!

$340 to repair a loose hose clamp

Would removing or loosening this hose be something a shop would do when draining/flushing/refilling the coolant ???

Not talking to the void at all. I was dealing with pavement sealing my driveway and cleaning nine outdoor equipment carburetors in the ultrasonic hot tank yesterday so I didn't check in here. Still have three to go and one is a beast to get to down inside a ZTR mower.

If that hose is nasty to get to I doubt a shop would mess with it flushing the coolant. Surprising she got away with it from MT to MI and MI to CO towing a gooseneck with horses inside. She must be living right cause the good lord is looking out for her.

[1976gmc20]

Originally Posted by fun in dirt

You're not talking into a void friend, I hear ya
Over the phone diagnostics & on the road repairs are things that cause major headaches & wallet hurt sometimes. Sounds like the good Lord & good luck is on her side though!

Well, a Good Samaritan neighbor of her friends drove 7 hours round trip from the west slope to Denver to haul her and her gooseneck and all her critters to her friends' place.

The thing that's bothering us now is this: one morning after she got back to Michigan her truck wouldn't start. She called for a tow and the driver asked to look at it first. He found the fuel filter housing was loose and it had lost prime. I had just had the fuel filter(s) changed in Billings before she came and got the pickup and drove it back east

I also had the dealer drain/flush/refill the engine coolant, and now the mechanic in Denver says he found a loose clamp on the bypass hose. I can't imagine that they would have messed with that at the dealer but it sure is making me wonder ...? Obviously, I'm not too happy with the Chevy dealer right now. We didn't buy her pickup from them because they don't keep anything that old on the lot, but I bought a 2016 from them a year ago, and I had over a grand worth of service done on the 2002.

Anyway, I'm glad that it's something relatively simple and not something like a head gasket. Now she's got to get a ride back over the mountains next week to get her pickup back. I think when she gets back over to the ranch that she should load up the trailer real heavy and drive it up the west side of Monarch Pass and back just to test it out on a hard pull before she ever takes off with a loaded trailer on a long trip again She's only about 30 miles west of the summit where she's staying now.

[hatzie]

Sloppy workmanship?
Dirtbag mechanics are lots of places. No pride in their workmanship at all. It's one of the main reasons I do all my own work.

No excuse at all for the fuel filter coming loose.

I just looked up the water pump bypass on the dirtymax. It's a tube with o-rings on both ends. It looks like they have to come off to R&R the thermostat.
It's a whole lot easier and more accessible to R&R than the old smallblock bypass hose.

This guy talks about using a non-standard fuel injection o-ring on the thermostat end of the tube and he says GM techs usually don't replace the o-rings.

GM 94011603 Radiator-By-pass Pipe LOWER Seal 94011603 to the water pump.

GM 94051259 Fuel Injection O-Ring UPPER seal on the end of the tube where it goes into t-stat housing.

DURAMAX Water Pump Bypass Tube Remove and Replace...

[1976gmc20]

Yeah, I already found and watched that same video.

But do you think they would take that apart just to change/flush coolant ????

As far as I understand what my daughter told me that the mechanic said, the leak is that short rubber hose and one of the clamps was loose and it blew off. If I had been there I might have been able to figure it out and maybe even get it back together and tighten the clamp. But she said "pink" and I thought "ATF" and expected that one of the transmission cooler line fittings was leaking (they replaced both at the shop also).

I don't work on stuff much anymore if I can help it. For one thing I don't know much about the newer vehicles and for another it just hurts so much. I did replace the oil pressure sender on the jeep recently but that was a trivial job. I hired a guy to come replace the pitman/idler on my 89 pickup, though a couple years back I replaced a ball joint, and later both front axles.

[hatzie]

Fresh Prestone Dexcool premix is kinda red or pink.

The small diameter hose on that sheet metal octopus between the thermostat housing and the water pump might actually be a reasonable place to hook up the flush gear to the cooling system.

Don't let your body stop you from doing things you like to do.
I'm getting sore more than I used to on cold days and I need to pull myself up when I get down on the ground to work on stuff but I'll be darned if I'll stop just cause it hurts. I like working on the machinery so I'll keep doing it. I move slower than I used to cause it hurts but I ain't gonna stop.
I dug 18 one foot deep holes along the property line early in the week and I'll be digging up some beech, maple, and oak saplings in the woods, mostly rock maple if I marked em right last fall, to put in those holes with chicken doodie, dirt, and peat next week after the freeze goes back to spring. I'm moving some volunteer antique lilacs and forsythia too. They'll be my mark on this place a century after I'm dust.
I've had arthritis in my hands and other joints since I was a young teen. If my shoulders, hands, hips, and knees hurt in the morning I know I'm still alive.

[1976gmc20]

Originally Posted by hatzie

Fresh Prestone Dexcool premix is kinda red or pink.

The small diameter hose on that sheet metal octopus between the thermostat housing and the water pump might actually be a reasonable place to hook up the flush gear to the cooling system.

Well, IF that's what they did then I'm going to raise Hell with the dealer here and demand that they pay her repair bill in Denver plus associated expenses from being stranded.

Don't let your body stop you from doing things you like to do.
I'm getting sore more than I used to on cold days and I need to pull myself up when I get down on the ground to work on stuff but I'll be darned if I'll stop just cause it hurts. I like working on the machinery so I'll keep doing it. I move slower than I used to cause it hurts but I ain't gonna stop.
I dug 18 one foot deep holes along the property line early in the week and I'll be digging up some beech, maple, and oak saplings in the woods, mostly rock maple if I marked em right last fall, to put in those holes with chicken doodie, dirt, and peat next week after the freeze goes back to spring. I'm moving some volunteer antique lilacs and forsythia too. They'll be my mark on this place a century after I'm dust.
I've had arthritis in my hands and other joints since I was a young teen. If my shoulders, hands, hips, and knees hurt in the morning I know I'm still alive.

Oh, I still have plenty to do. I just got back from a 2-3 mile hike in the woods. I split all our firewood by hand. We might ride our horses after lunch if it doesn't rain.

Last fall we bought another 20 acres next door and it is all overgrown with juniper so I've been gradually clearing out a turn around and camping site among the pines. The stuff is nasty and grows every which direction. I get a few fence posts and a little bit of small firewood and a LOT of brush to drag down the hill into a pile (and then climb back up again!).

And I need to finish up this stupid room out here and build some sort of floor inside it that won't rot out at least for my lifetime. And I still need to side the barn instead of just tarp walls, and I want to re-frame the other screened porch and close it in and install some take-out windows that we have sitting around.

There was no way I could do all that stuff on her pickup before she came and got it. We were tearing out the old hot tub during that time. I bought the rear brake pads for it but I didn't even get that done and just gave her the pads to install later. She's done it before, on smaller vehicles.

[1976gmc20]

Well, NOW - a year and a half later - she apparently has big transmission problems. Shifting weird and RPM all over the place.

Broke down in Woodland Park west of Colorado Springs again pulling gooseneck with horses. She got a mobile mechanic to "reset" the TCM and only got to Florissant before it started acting up again. She got friends with a pickup to come get her and her friend and her trailer.

So the little shop there say they can't find anything wrong with it. No TCM codes. They told her to just come drive it home empty but her trusted mechanic on west slope says "No!"

So her options are:
1) get a ride and go drive it home
2) have insurance pay for tow to dealer in Col Spgs (they can't work on it until 22nd)
3) Somehow tow or haul it 100++ miles over Monarch Pass to her local trusted mechanic

[hatzie]

Might be a good idea to drag it onto a trailer and haul it to her mechanic.
I wouldn't trust a dealership parts changer as far as I could throw them.

[1976gmc20]

Originally Posted by hatzie

Might be a good idea to drag it onto a trailer and haul it to her mechanic.
I wouldn't trust a dealership parts changer as far as I could throw them.

Yeah, that was my suggestion. It runs and drives so it could just be driven up onto a trailer. Only problem she said everyone around there is cutting and hauling hay right now so nothing available to beg/borrow/hire.

I am of course 800 miles away in Montana.

[hatzie]

Originally Posted by 1976gmc20

Yeah, that was my suggestion. It runs and drives so it could just be driven up onto a trailer. Only problem she said everyone around there is cutting and hauling hay right now so nothing available to beg/borrow/hire.

I am of course 800 miles away in Montana.

Just plain bad time of year to break down like that and be far away from dad. Tho I've rescued my dad and mom on more than one occasion. They're pushing 80 and I'm on the downslope toward 60. Reminds me of the Bonnie Rait tune Nick of Time.

Buying twin axle 7200 & 9600 GVW trailers is expensive anymore. Glad I got my 9600 back in 2017.
Then you still need to find a rig big enough to haul it.

If I was a lot closer I'd offer to help but I'm halfway across the country in New England.

If her mechanic says it's not a good idea to empty the cab and bed out so the only extra weight is the driver and then drive it to him empty... he likely has an idea what's wrong and he might be able to fix it if it's not driven any noticeable distance.

[1976gmc20]

Originally Posted by hatzie

Just plain bad time of year to break down like that and be far away from dad. Tho I've rescued my dad and mom on more than one occasion. They're pushing 80 and I'm on the downslope toward 60. Reminds me of the Bonnie Rait tune Nick of Time.

Buying twin axle 7200 & 9600 GVW trailers is expensive anymore. Glad I got my 9600 back in 2017.
Then you still need to find a rig big enough to haul it.

If I was a lot closer I'd offer to help but I'm halfway across the country in New England.

If her mechanic says it's not a good idea to empty the cab and bed out so the only extra weight is the driver and then drive it to him empty... he likely has an idea what's wrong and he might be able to fix it if it's not driven any noticeable distance.

She's a big girl now. I haven't heard yet what she decided. I dunno what was in the cab & bed but the main load had been that big old steel gooseneck trailer (4 horse + tack room/sleeper).

I could pull it on a trailer (I think - 21K GCVW) with my 2500 but it would be a 2000 mile round trip just to move it maybe 140 miles. We used to make that drive a lot (C.S. <--> Gunnison) and I think it was about 180 miles total and the truck is maybe about 40 miles west of C.S.

I thought maybe it could be moved with front wheels on a dolly but I don't think there is any way to put the electric TC in neutral?

I'm just damn glad my 2016 has the manual TC lever!

[hatzie]

With the engine running put the transmission in Neutral and the transfer case in 2HI.
There are white lines on the RH side of the transfer case shift buttons connecting 2HI, N, & 4LO.
Press and hold 2HI & 4LO for 10 seconds or thereabouts.
The transfer case will shift into neutral and the red N lamp will light indicating it's in Neutral.

[1976gmc20]

Originally Posted by hatzie

With the engine running put the transmission in Neutral and the transfer case in 2HI.
There are white lines on the RH side of the transfer case shift buttons connecting 2HI, N, & 4LO.
Press and hold 2HI & 4LO for 10 seconds or thereabouts.
The transfer case will shift into neutral and the red N lamp will light indicating it's in Neutral.

Thanks!

Sounds like her insurance may pay for towing it over the mountains to her home area and mechanic. After all this the shop there in that little town where she stopped can't find anything wrong with it.

[1976gmc20]

She got it towed back to Gunnison and her mechanic hasn't yet figured out what is wrong with it.

I think based on the symptoms that I would drop the transmission pan and see what it looks like.

[1976gmc20]

Now her mechanic thinks there is nothing wrong with the transmission.

Maybe a fuel problem that caused the computer to make it shift rough.

[hatzie]

Originally Posted by 1976gmc20

Now her mechanic thinks there is nothing wrong with the transmission.

Maybe a fuel problem that caused the computer to make it shift rough.

Sounds like he's actually diagnosing it and not just throwing parts at it.
Hope she gets it back on the road for a reasonable price.

[1976gmc20]

Originally Posted by hatzie

Sounds like he's actually diagnosing it and not just throwing parts at it.
Hope she gets it back on the road for a reasonable price.

Thanks. Last I heard she was just going to take it home and drive it. She's thinking about hooking up the gooseneck with a load of horses or something and go drive up the nearby eleven thousand foot mountain pass to see if she can replicate the symptoms.

[hatzie]

Originally Posted by 1976gmc20

Thanks. Last I heard she was just going to take it home and drive it. She's thinking about hooking up the gooseneck with a load of horses or something and go drive up the nearby eleven thousand foot mountain pass to see if she can replicate the symptoms.

Don't think I'd take a trailer full of live animals on a drive like that without a backup tow machine following me.

If she got a slug of bad fuel it's entirely possible to have strange symptoms from the PCM frantically modifying parameters to fix it.

[1976gmc20]

Originally Posted by hatzie

Don't think I'd take a trailer full of live animals on a drive like that without a backup tow machine following me.

If she got a slug of bad fuel it's entirely possible to have strange symptoms from the PCM frantically modifying parameters to fix it.

Or some other fuel system problem. It is frustrating when one minor problem can now (well, last 20 years or so) create a bunch of other unrelated problems.

She literally lives at the foot of this pass. So she could drive up to the top and turn around and come back down the same way, or turn around at one of the pull-offs part way up the ten mile or so grade. I agree dead weight would be better.

(sorry I don't have notifications turned on and I don't check in here very often anymore)