Transmission question!

[Yamahafan]

Ok, so when I bought my 02 yukon they had just rebuilt the transmission, and it had a 1 year warranty. My wife and son and I were traveling back home from out of town, running 80 down the highway, smooth sailing. Then out of nowhere my truck just started revving, and wouldn't shift into 3rd after that. I got it back home and they fixed it. But they called me and told me the transmission wasn't blown, that a seal on the transfer case blew, and that's why that happened, (After they had my truck for two weeks!). I am very mechanically inclined, and work on most of my own stuff, but I don't touch transmissions. I also don't understand how that would keep my truck from shifting. Is there a limp home mode or something that caused this? Or are they just yankin my chain and trying to cover up a screw up on the previous rebuild? The transmission gave me absolutely no warnings of going out, no hard shifting, no slipping, nothing like that, just suddenly stranded us in the middle of nowhere!

 

[rockola1971]

Your gut feeling was right. There isnt a seal in the transfer case that would cause the transmission to keep from shifting. They blamed it on the transfer case so they could charge you for the "repair" of the transfer case. Tell them you want to know which seal they believe caused this in the transfer case then take it to another shop and get it documented that the case had no repairs and this isnt possible then sue the first shop in small claims court if there is enough $$ involved.

 

[Yamahafan]

Luckily they went ahead and fixed it all at no cost to me. I did overhear an employee had recently been fired, so im thinking maybe he was half assing repairs, amd they are trying to play fireman. I just thought it was a little fishy that they had it two weeks for a "seal." It seemed to me that if the transfer case blew a seal, I wouldn't have 4x4 eventually, but I would have still been able to get my family home.

 

[rockola1971]

Luckily they went ahead and fixed it all at no cost to me. I did overhear an employee had recently been fired, so im thinking maybe he was half assing repairs, amd they are trying to play fireman. I just thought it was a little fishy that they had it two weeks for a "seal." It seemed to me that if the transfer case blew a seal, I wouldn't have 4x4 eventually, but I would have still been able to get my family home.

If you had a seal blow in your transfer case (NP246E) which would dump all the fluid out then you wouldnt have 2 or 4wd once a bearing locked up or came apart chucking the drive chain through the case.

 

[6speedblazer]

i bet the input shaft seal went out on the transfercase. When this happens fluid from the transmission gets pumped into the transfercase.

if enough trans fluid is pumped into the tcase it could cause the trans to slip and or fail to change gears.

 

[Wes 03 Yukon]

I lost second gear in my 03 Denali virtually overnight. There was no slipping or other symptoms leading up to the failure. During the rebuild, I decided to rebuild the valve body and add a shift kit to firm up the transitions. Well, thank goodness I did, because I found the root cause of the entire failure to be a broken spring behind one of the shuttle valves that prevented the valve from moving to the second gear position. The way you lost your gear suddenly out of nowhere like that reminds me of mine. If you lost fluid into the T- case through a bad seal, it would have slipped at least a little bit before giving out on you. It sounds more likely that you suffered from a solenoid or valve failure, or something along those lines. And don't be afraid to tear into a tranny, get the rebuild manual and go to town. They are intimidating at first, but like anything one step at a time will get you there. Took me 5 days to pull, fully overhaul, reinstall, and test flog and I had a ton of fun doing it.

 

[01ssreda4]

i bet the input shaft seal went out on the transfercase. When this happens fluid from the transmission gets pumped into the transfercase.

if enough trans fluid is pumped into the tcase it could cause the trans to slip and or fail to change gears.

Its always easy to tell who actually has mechanical knowledge and who spews BS and makes everyone dumber. Thank you for this post sir, you make these forums useful. Hopefully future readers can tell the difference.

 

[Yamahafan]

I lost second gear in my 03 Denali virtually overnight. There was no slipping or other symptoms leading up to the failure. During the rebuild, I decided to rebuild the valve body and add a shift kit to firm up the transitions. Well, thank goodness I did, because I found the root cause of the entire failure to be a broken spring behind one of the shuttle valves that prevented the valve from moving to the second gear position. The way you lost your gear suddenly out of nowhere like that reminds me of mine. If you lost fluid into the T- case through a bad seal, it would have slipped at least a little bit before giving out on you. It sounds more likely that you suffered from a solenoid or valve failure, or something along those lines. And don't be afraid to tear into a tranny, get the rebuild manual and go to town. They are intimidating at first, but like anything one step at a time will get you there. Took me 5 days to pull, fully overhaul, reinstall, and test flog and I had a ton of fun doing it.

I have been doing a lot of reading up on shift kits and stuff to beef up the 4l60E. I may take your advice and just get the manual and tear into it, it is running fine now, but I don't trust it enough to take a long road trip yet. Which shift kit did you install, and how has yours held up after. Mine seems to fall on its face when it shifts from second to third now, no hard shifting or anything, just waaaay too underpowered it seems. Also seems to hit OD way too soon. Love my yukon, and gotta rebuild the confidence into it little by little now. I take my son camping, offroading, overlanding etc. in this thing, so I need to absolutely make sure it is rock solid in the transmission department.