Transmission not shifting real great 2004 Yukon XL Denali

[Marinevet]

I have a 2004 Denali with a 6.0/4L65E/AWD, with 135,000 miles on it. When shifting at low RPMs, it shifts decently ok, but at high throttle shifts (not floored, I don't drag race with it, but like you would use on an uphill interstate on ramp), when it goes to shift the engine revs up an extra 5-700 RPMs before it actually shifts, and the shifts are not very firm. This is most noticeable in the 2-3 and 3-4 shifts. Everything I am reading online says it is probably going to need to be rebuilt. I bought it from the dealer three years ago, and it was doing it then but a lot worse, so I made them rebuild it before I bought it. It only had 68,000 miles on it then though. There are no CEL codes for the tranny, and most of my driving is highway miles. Up until now, I have only pulled 3500 lbs with it twice, other than that I haven't towed anything. I have a 7000 lb bumper pull camper that I would like to pull with it, since I have a big family, but I won't do that until I get whatever is wrong with it fixed. What are your thoughts?

1. Does it need rebuilt, or could I try putting a shift kit in it first to see if that makes the shifts firmer?
2. Since I plan on towing heavy stuff with it, would it be worth it to buy a beefed up version of it and install it?
3. Is there something else I could check out first before I spend all that money on it?
4. In the meantime, if I push the towing button will that make it last longer for now?

Sorry for all the questions, I am getting fairly frustrated, because this is a great vehicle, rides like a dream, but if this is the second time in 70,000 miles that this transmission needs to be rebuilt that's going to suck. Thanks in advance for the opinions.

Jeremy

 

[mizzouguy]

Id say the dealer picked a cheap place to get it rebuilt. I would take it to a reputable tranny shop of your choosing and let them diagnose it, telling them everything you just said. I'd imagine they will want to do a rebuild with towing in mind. I would have to think a heavy duty rebuild would be cheaper and better quality than a new tranny built to oe specs.

 

[adventurenali92]

How often do you have the transmission serviced?

 

[Marinevet]

I hadn't had it serviced since it was "rebuilt", I guess I didn't know how often it needed changed. I should add that it don't do it near as bad when it's cold too. I guess I could try just a fluid and filter change first. Is there anything I can do to adjust shift pressure while I have the pan off? I don't know much about how these electronically shifted ones work. Thanks.

 

[adventurenali92]

Couldn't tell you anything about shift pressures. But I would definitely recommend checking your fluid. That's alot of miles without a fluid and filter change. I check to ensure proper fluid level religiously now, after having to have my 4L65E rebuilt at only 85k miles. It should always be a nice pinkish color and should not smell burnt. If your fluid isn't pink in color it's definitely time for a fluid change.

 

[rockola1971]

I wouldnt change the fluid and filter. Let the tranny shop do it while they have the pan dropped having a look at the valve body. You could have a few different things wrong. Sticking valve(s), countersunk check ball in seperator plate to name a few. There is no user adjustment of line pressure. The PCM can be programmed to firm up shifts but that would just be covering up a problem and may not end up as intended. Id be curious as to color of fluid, smell and amount of material in the pan after it is dropped. Find a reputable shop!

 

[adventurenali92]

I wouldnt change the fluid and filter. Let the tranny shop do it while they have the pan dropped having a look at the valve body. You could have a few different things wrong. Sticking valve(s), countersunk check ball in seperator plate to name a few. There is no user adjustment of line pressure. The PCM can be programmed to firm up shifts but that would just be covering up a problem and may not end up as intended. Id be curious as to color of fluid, smell and amount of material in the pan after it is dropped. Find a reputable shop!

Yeah this is an excellent point. A reputable trans shop will be able to find all those things.

 

[rockola1971]

After you tell your symptoms to a shop and they blurt out "it needs a rebuild" without even dropping the damn pan... Run! Run very fast! Squeeze your cheeks while running and dont let them get close to you!

 

[Matahoe]

After you tell your symptoms to a shop and they blurt out "it needs a rebuild" without even dropping the damn pan... Run! Run very fast! Squeeze your cheeks while running and dont let them get close to you!

If the shop is very reputable and provides proof other than the fluid color then I wouldn't have a problem with them providing me with this answer. After reading reviews pick three shops, get estimates from those three shops. And for goodness sake don't let them dismantle anything to the extent that you cant drive the vehicle away. rebuilt transmissions usually go for $1200. This should include a new torque converter and sun shell. Add a few hours labor for removal and installation.a bout ~$250. Diagnostic fees usually waived by this point. Your looking at about $1500 total.

 

[rockola1971]

If the shop is very reputable and provides proof other than the fluid color then I wouldn't have a problem with them providing me with this answer.

Thats because you never worked at a transmission shop and know the games they play and how they go about it. Not all of course but it happens often.
For example: The ****** old cars that need rebuilt get refilled with filtered USED transmission fluid. Not New. Because more than likely the engine will die before the tranny does again.