Delayed Shifting

mmayo · September 13, 2005

Sometimes after my truck has sat overnight or most everytime it sits for a couple days w/o driving it doesn't seem to go into reverse all the way. It seems that I have to rev the engine up to higher RPMs than I should in order to reverse out of the garage. I'm thinking that its torque converter drainback. I only have about 300 miles left on my 36k warranty so if its something I can get fixed I'd like to. I have the 6.0L engine w/ the auto tranny. What do you guys think the prob could be & can it be fixed?

Thanks - Mayo

mmmikkke · September 13, 2005

If it's reverse-only, I'd be more inclined to think it could be a forward clutch not disengaging. On my last THM400, which was in my '86 K25 Chevy, this happened. At first, it was, on each morning, a sluggish reverse, where I needed to hit the gas a little more than expected to get it moving. It didn't seem to be slipping; it was just resisting like I had the brake on partially.

A week or so after this started, I noticed that the reverse clutch was slipping. I took it in to a trusted trans mechanic, and he rebuilt it. Turned out that one of the dowels that holds the clutch (band?) in place had drifted out of its hole, leaving the clutch engaged when it wasn't supposed to be. That wore it out quickly.

Does this sound at all like your situation?

mmayo · September 13, 2005

Well it does seem like the clutch isn't fully disengaging but I dont know if its just in reverse or not - I only notice it when backing out of my garage after I haven't driven it for a day or so. It's also at a slight incline in my garage(front tires are about 7" higher than the rear) but I don't know if that would affect anything or not. It's usually fine if I drove it the night before. It doesn't seem to be resisting though, just feels like its not fully engaged into gear like if it were a standard & I had the clutch partially pushed down.

2004GMC2500HD · September 13, 2005

I have an 04 GMC 2500 HD 4x4 with the 8.1 / allison combo.

I park my in my driveway at a slightly uphill angle. It sometimes sits for a week or more at a time without being started or moved.

When I start it up and put it in reverse it won't engage. I just roll backwards out of my driveway because of the incline and then when I get onto the flat street it will slowly start to engage. By then I am already putting it into drive, which takes quite some time to engage. After it engages into drive it works perfectly fine.

Just seems like all the fluid has drained out of it and it takes time to pump it back into the tranny. Since I am nothing even close to a mechanic this is my non-professional diagnosis. Its under warranty so I figure if it breaks, oh well it will get fixed.

The truck is kinda a hunk of junk anyway. Its been to the shop for 8 or 9 things now in 14000 miles. The only GMC dealer around isn't all that helpful either so I doubt they would find anything wrong with it plus I don't want them to have it for a week at at time either.

mmayo · September 13, 2005

Thats about what I do as well, although I dont have the Allison. My dad has an '01 D/A & he says his does it as well. I was just wondering if there is a fix for the problem or if its just something I'll have to live with. I haven't had many issues w/ my truck. A couple minor probs that were fixed unter warranty but nothing major.

mmayo · September 14, 2005

Anyone else???

dalez · October 21, 2005

I had this same problem after my truck sat for 4 weeks in the garage. It hesitated going into forward because it is backed into the garage. I pulled it out of the garage and it felt like the transmission was slipping. I stopped and tried to put it in reverse and it would not go backward. I put it back into drive and it continued to slip but after a block or so it felt normal but the check engine light came on. I drove it 5 miles and stopped and tried to put it into reverse and it would still not go into reverse. I shut it down and started it up 2 times and it finally when into reverse. It has been 2 weeks since it happened and i took it to my local gm dealer so I could find what the codes were and the following codes came up. p0713 & p1709 The bulletin that came up for those codes was Allison transmission delayed engagement, cold hesitation, MIL illuminated. The truck is an 01 2500hd crew 8.1 allison with 55,000 miles. The service man said he estimated it would cost $700 to fix. has any one had this happen and have you had this bulletin done to fix it.

Shooter_va · October 22, 2005

Mine does it when sitting for a week or so with the nose uphill. I didn't do the bulletin, I usually start it up, let it run for a couple of minutes, shut the engine off, restart and go on (this works most of the time, when not, I reset the codes with my scanner). The drain back of the Allison is a common problem with the "older" trucks.

trask · October 22, 2005

Mv 04 6.0 w/auto tranny does the same thing after sitting for a couple of days on a slight incline.

MemphisDoug · October 26, 2005

My truck does it too. It sits in the garage for days at a time and when I start it up and try to back out of the garage, I get the delayed engagement. Sounds like it is a common problem.

Bud · October 26, 2005

I have an 04 GMC 2500 HD 4x4 with the 8.1 / allison combo.

I park my in my driveway at a slightly uphill angle. It sometimes sits for a week or more at a time without being started or moved.

When I start it up and put it in reverse it won't engage. I just roll backwards out of my driveway because of the incline and then when I get onto the flat street it will slowly start to engage. By then I am already putting it into drive, which takes quite some time to engage. After it engages into drive it works perfectly fine.

Just seems like all the fluid has drained out of it and it takes time to pump it back into the tranny. Since I am nothing even close to a mechanic this is my non-professional diagnosis. Its under warranty so I figure if it breaks, oh well it will get fixed.

The truck is kinda a hunk of junk anyway. Its been to the shop for 8 or 9 things now in 14000 miles. The only GMC dealer around isn't all that helpful either so I doubt they would find anything wrong with it plus I don't want them to have it for a week at at time either.

<{POST_SNAPBACK}>