2007 Sierra Transmission problems

V1ZION · January 19, 2014

Hey guys, I have a 2007 Denali with the 6.2L engine and six speed transmission and Im having some issues. It all stated around may of last year I had the shift track sensor replaced at the dealership. Everything seemed fine but one day my dad was with me and mentioned if it always was a little slow going into reverse, I didn't notice it before having the sensor replaced, so I thought maybe the sensor was just needing to be calibrated, anyways I drove it like normal because it was shifting properly threw every other gear and it was only slow if the transmission was hot. fast forward to July and me and my buddies are about to merge onto the freeway which was up hill so I floor the gas and go well the truck doesn't it red lines and I see the check engine light come on, great. So I let the truck cool off for bit the transmission was at 100 Celsius but the engine was fine, once it cools off we drive up to the hotel and everything seems fine except its really slow going into reverse now. Anyways it was a couple days before the dealership where I was at could get it in, but the truck was driving fine so I just drove it gingerly, I did notice that the tranny was running warm though like 70-80 degrees in town but i just thought it was because it was +35 out. So the dealer ship takes a look and the codes that were thrown were from the pressure silnoid so I thought ok great, why did it go off, well heres the funny part, the dealership, in my home town, where they replaced the shift track sensor, well they over filled the transmission by 4 1/2L. 4 1/2L!!! what the shit, so the dealership where im staying does a transmission flush and put the correct levels in, says its all good. Im driving it but it still seems to be a little slow going into reverse, and sometimes it still redlines if I have it gunned at 110km/h.

Fast forward to now and Im starting to get worried, its still low going into reverse, but only when the transmission has reached around 50 degrees and then I notice it. The delay hasn't got any longer though, and it still does the redline and 110 km/h. So I checked fluid levels and all is good, It doesn't smell burnt and its still a nice pink. But I want to get it checked because its starting to shift funny, less smooth I should say. The truck has 150,000 km on it Im just praying that I don't need to have the transmission rebuilt because its not slipping it just doesn't feel as smooth. Is there a chance that it could just be the pressure silnoid or do I see a new transmission in my future.

scooby5121 · January 19, 2014

rob, will chime in aka Govtech !!!!!!!!!!!

gmtech4 · January 20, 2014

i never touched one of these trannys ...but i have to ask wtf is a shift track sensor ?lol

i'll say it again ,,,,transmissions problems and the internet dont go together

you're punchin it at 110 and wonder why it goes max rpm ,,,,geez i wonder why !!!! stop doing that !!!! ya dont need to get 2 or 3 gears at that speed ever !!!!,,,ya want to pass ,,,go up 1 gear ..

take it in too a tranny tech and have the tranny pressures gone thru ,,,thats all ,no help from me except that

V1ZION · January 20, 2014

i never touched one of these trannys ...but i have to ask wtf is a shift track sensor ?lol

i'll say it again ,,,,transmissions problems and the internet dont go together

you're punchin it at 110 and wonder why it goes max rpm ,,,,geez i wonder why !!!! stop doing that !!!! ya dont need to get 2 or 3 gears at that speed ever !!!!,,,ya want to pass ,,,go up 1 gear ..

take it in too a tranny tech and have the tranny pressures gone thru ,,,thats all ,no help from me except that

sigh... I know it sounds bad and Im probably do more harm than good putting it off, but I really really don't want to have someone look at it and tell me that shits ****ed I truly don't want to hear "you need new clutches" or "needs to be rebuilt". Your right about not having to go so fast, but Im 18 and when I pass someone I really don't like to be in the other lane for that long.

also nice to see someone else from Alberta on here.

2017SierraSLT · January 20, 2014

110 kilometers per hour is only 68.3508 MPH.

txab · January 20, 2014

110 kilometers per hour is only 68.3508 MPH.

To Rob, that's sound barrier territory.

txab · January 20, 2014

sigh... I know it sounds bad and Im probably do more harm than good putting it off, but I really really don't want to have someone look at it and tell me that shits ****ed I truly don't want to hear "you need new clutches" or "needs to be rebuilt". Your right about not having to go so fast, but Im 18 and when I pass someone I really don't like to be in the other lane for that long.

also nice to see someone else from Alberta on here.

Sounds like whoever paid for your rig needs to pony up for some trans work

mike94silverado · January 20, 2014

You don't want to hear you've got a broken transmission? Think anyone does? And it's not a

Race car so if you want to go fast I suggest you get rid if it you say "I'm 18" like it's some sort of excuse to drive like that...

Sent from my iPhone using Tapatalk

V1ZION · January 20, 2014

Sounds like whoever paid for your rig needs to pony up for some trans work

Well then it looks like I will be paying then.

V1ZION · January 20, 2014

You don't want to hear you've got a broken transmission? Think anyone does? And it's not aRace car so if you want to go fast I suggest you get rid if it you say "I'm 18" like it's some sort of excuse to drive like that...Sent from my iPhone using Tapatalk

Your right it absolutely isn't an excuse, and driving like that is dangerous I know. But when there's a long open peice of highway with no one on it, it's hard to resist the urge to go faster then the designated speed limit.

txab · January 21, 2014

Well then it looks like I will be paying then.

Run it by a trans shop and let them take a look at.

gmtech4 · January 21, 2014

sigh... I know it sounds bad and Im probably do more harm than good putting it off, but I really really don't want to have someone look at it and tell me that shits ****ed I truly don't want to hear "you need new clutches" or "needs to be rebuilt". Your right about not having to go so fast, but Im 18 and when I pass someone I really don't like to be in the other lane for that long.

also nice to see someone else from Alberta on here.

there is lots of us from *&^*&in cold ville ,,,,,where r u ? im 2 hrs east of Edm

PS,you guys should've seen me as a young douche fresh in the army with wheels lmfao !!!!,,,,,there are stories lol

Edited January 21, 2014 by govtech4

V1ZION · January 21, 2014

there is lots of us from *&^*&in cold ville ,,,,,where r u ? im 2 hrs east of Edm

PS,you guys should've seen me as a young douche fresh in the army with wheels lmfao !!!!,,,,,there are stories lol

Im 4 hours north of Edmonton, or the next big center north, you should know where that is considering theres only one haha.

gmtech4 · January 22, 2014

Im 4 hours north of Edmonton, or the next big center north, you should know where that is considering theres only one haha.

thats where all the money is and insane rental costs !!!

j-ten-ner · January 22, 2014

...but I really really don't want to have someone look at it and tell me that shits ****ed I truly don't want to hear "you need new clutches" or "needs to be rebuilt"...

Back when I had my '07 Sierra I was thinking the same.

I thought a fluid change can fix it. It was better though. For sure.

But another 15000km down the road I spend 3.5 grands (before taxes!) for a complete rebuilt.

And one thing is for sure. You don't wanna hear someone say: "If you had brought the truck in earlier we might would have been able to fix it with a change of some clutches or bushings..."

so long

j-ten-ner