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.

 

[Matahoe]

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.

I know the games...and this wouldn't be a very reputable shop in my book. If they pulled this kind of stunt it might eventually backfire on them at some point. What about former employee feedback or whistleblowers? It isn't all that easy to make a quick buck. Those types of shops are fly by night and not reputable. I don't actually work in any type of shop but I have a family of machinists and mechanical engineers. Also you tend to see this stuff being from Michigan..so yeah

 

[rockola1971]

I know the games...and this wouldn't be a very reputable shop in my book. If they pulled this kind of stunt it might eventually backfire on them at some point. What about former employee feedback or whistleblowers? It isn't all that easy to make a quick buck. Those types of shops are fly by night and not reputable. I don't actually work in any type of shop but I have a family of machinists and mechanical engineers. Also you tend to see this stuff being from Michigan..so yeah

Back in the early 90s it was common to have the tranny shops that you didnt want to goto because they were known by word of mouth concerning their practices. But not everybody knew which shop you didnt want to goto. Those people kept those shops in business for well over a decade +.

 

[GeorgesBlazah]

My trans does the same thing, same truck not an XL though. I took it to a shop and he drove it, basically told me it could do that forever or just fail. I think he thinks I was being too picky. Either way, I bought a camper and have a few trips planned this year, when/if it goes, ill be sure to post.

BTW whats your trans temp just running around town? Mine runs around 150-170 once its warmed up.

 

[Marinevet]

In the summer time, mine runs right around 150-170 as well, the only time I have ever had mine even get close to 200 was lots of in town driving on a hot summer day with front and rear A/C blasting.

Thanks everyone for responding on this. If I decide to do the fluid and filter change myself, do you guys run regular fluid or synthetic? Any additives? I am not sure where to take anything around here, because I have always wrenched on my own stuff.

Jeremy

 

[the blur]

My 2003 Yukon Denali. The tranny slips between 1st & 2nd gear (intermittently) for well over 100,000 miles. It started doing it at 98,000 miles. Now the truck has over 200,000 miles on it. I always lift off the throttle when it happens, so the engine doesn't rev up. But it's still hanging on.

 

[TahoYukon Forum]

Does it have toe-haul button?
Does it seem like that tow-haul button is active? And maybe the cluster light is inop... Maybe? Always check the cheapest solution first, hope it doesn't cost u much bud.
I think that is how my 03 Tahoe acts, but not sure, I'll check after a bit.

 

[blklab01]

I have an 04 (Denali). I was having slow shifts between 1 and 2 , kind of like it was slipping a little. This coincidently started a few days after a battery replacement. Since the trans is controlled electronically , I decided to duscobmy battery over night to start the reset process. The next day after the battery reconnect , the shift points were almost normal, but recovered completely after 100 miles,,,,, I would recommend this prior to any trans service.

 

[Marinevet]

My 2003 Yukon Denali. The tranny slips between 1st & 2nd gear (intermittently) for well over 100,000 miles. It started doing it at 98,000 miles. Now the truck has over 200,000 miles on it. I always lift off the throttle when it happens, so the engine doesn't rev up. But it's still hanging on.

That's what I do with mine too, I just try to baby it, but I feel like if I start trying to tow with it that's going to accelerate the problem quite a bit.

Does it have toe-haul button?
Does it seem like that tow-haul button is active? And maybe the cluster light is inop... Maybe? Always check the cheapest solution first, hope it doesn't cost u much bud.
I think that is how my 03 Tahoe acts, but not sure, I'll check after a bit.

The towing light works on mine still. I haven't tried driving it around in tow mode, but I may try that first.

Did anyone have a recommendation for good fluid or additives for the fluid and filter change? Sorry for the late response, I was gone on vacation for awhile. You all have been very helpful.

Jeremy

 

[Marinevet]

Do any of you all have a recommendation for good fluid or additives for the fluid and filter change? I am finally getting around to trying that out, nothing else has seemed to help yet. Another thing I've noticed, oddly enough, is that when the cruise is set, the transmission downshifts and upshifts between 3rd and 4th gear just find, no lag in the shift or anything. I'm hoping the fluid change helps my issue go away. Thanks again for all the help.

Jeremy

 

[sefiro]

High rpm shift points are normal for this generation of transmissions. Factory service manual spec shows a range of 1000 rpms from 12% throttle to wide open. +/-250rpm. Tow mode settings will raise this rpm range a bit.

A true rebuild sign would be burnt tranny fluid or material in the pan. A pan drop would ultimately be needed to see if a large number of metal shavings are stuck to the magnet. When replacing fluid, use dextron 6. It's fully compatible, synthetic, and recommended by gm for this generation of transmissions. Plenty of posts on how to change and not to use an external pressure pump.

If fluid is clear and minimal material (there is always a little bit after a new build break in), then valve body tune up, shift kit may be in order. You mentioned the dealer did some rebuild but did but give specifics. You'll need to drop the valve and inspect to see if oem or changed to a kit.

Your symptoms suggest the accumulate pistons/springs may be at fault (worn or broken). Or shift valves are leaking showing the shift point. These are accessed when when the pan and valve body is dropped.

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