Another bad GM transmission in my '19 Tahoe

[gapost]

Well I bought a high mileage Tahoe a few months ago and half expect to have transmission issues. This weekend, it started shuddering when downshifting, especially when turning a corner and not stopping (guessing in second). It would slip sometimes when upshifting. And most notably, the tranny fluid was way high after sitting. When cold or hot and checking the fluid, it was at the proper level. From when I have read, the converter must be bad.

So with 122,000, the truck is in excellent condition and has run perfect and I expect to keep it for a number of years so I've accepted the inevitable. I'm in a small town so I think we have one tranny shop and a Chevy dealer and GMC dealer. I'll go talk to them this week and get my options. I think I would go with a GM or Casper remanufactured, unless I get a really good feeling about the transmission shop for a rebuild. I've read the other threads and read what Nick says I should be looking for. I do all my own service on all my vehicles so I really hate letting someone else do the work. But it's just too big of a job for me without a lift.

 

[swathdiver]

The transmission thermostat causes the converters to come apart which then takes out the transmission. Address those two issues, run the severe service schedule from now on and she'll last twice that distance or more.

 

[gapost]

The transmission thermostat causes the converters to come apart which then takes out the transmission. Address those two issues, run the severe service schedule from now on and she'll last twice that distance or more.

Yes, when I bought it I put in the cooler bypass valve. Guess it was too late, lol.

 

[NickTransmissions]

Well I bought a high mileage Tahoe a few months ago and half expect to have transmission issues. This weekend, it started shuddering when downshifting, especially when turning a corner and not stopping (guessing in second). It would slip sometimes when upshifting. And most notably, the tranny fluid was way high after sitting. When cold or hot and checking the fluid, it was at the proper level. From when I have read, the converter must be bad.

So with 122,000, the truck is in excellent condition and has run perfect and I expect to keep it for a number of years so I've accepted the inevitable. I'm in a small town so I think we have one tranny shop and a Chevy dealer and GMC dealer. I'll go talk to them this week and get my options. I think I would go with a GM or Casper remanufactured, unless I get a really good feeling about the transmission shop for a rebuild. I've read the other threads and read what Nick says I should be looking for. I do all my own service on all my vehicles so I really hate letting someone else do the work. But it's just too big of a job for me without a lift.

Give me towards the end of the workday and ill put a list of everything that needs to be done on overhaul (parts, machining, etc).

Once I post the list, review it then ask any transmission rebuilders what they do to the 6l80s they rebuild and compare it to the list. If they dont do most/all of those things, id find another shop or buy a GM remanufactured unit.

 

[gapost]

Give me towards the end of the workday and ill put a list of everything that needs to be done on overhaul (parts, machining, etc).

Once I post the list, review it then ask any transmission rebuilders what they do to the 6l80s they rebuild and compare it to the list. If they dont do most/all of those things, id find another shop or buy a GM remanufactured unit.

Thank you Nick. I don't think I have a good re-builder available and am now thinking about installing a re-manufactured one myself. Is GM the only one to consider and will they let me install it myself and still have the warranty? I know it will need to be re-flashed at the dealer. Should I do the rear main seal at the same time? TIA

 

[NickTransmissions]

Thank you Nick. I don't think I have a good re-builder available and am now thinking about installing a re-manufactured one myself. Is GM the only one to consider and will they let me install it myself and still have the warranty? I know it will need to be re-flashed at the dealer. Should I do the rear main seal at the same time? TIA

Up to you on whether or not to replace the rear seal (if its not leaking id leave it alone. Contact GM and Jasper to learn more about what they offer and choose the best option from your perspective.

 

[NickTransmissions]

Thank you Nick. I don't think I have a good re-builder available and am now thinking about installing a re-manufactured one myself. Is GM the only one to consider and will they let me install it myself and still have the warranty? I know it will need to be re-flashed at the dealer. Should I do the rear main seal at the same time? TIA

Hey man, you can find the list and more in this thread

 

[gapost]

Hey man, you can find the list and more in this thread

At this point, I'm not sure I'm ready to give up on the tranny. I'm thinking about pulling the pan and seeing what it looks like and what new fluid does. Would it be worth it to pull the tranny and just replace the torque converter? It hasn't been that many miles that it started having notable issues (less than 100)

 

[NickTransmissions]

At this point, I'm not sure I'm ready to give up on the tranny. I'm thinking about pulling the pan and seeing what it looks like and what new fluid does. Would it be worth it to pull the tranny and just replace the torque converter? It hasn't been that many miles that it started having notable issues (less than 100)

Yes, if that's the original JMBX factory converter, dump it and purchase an upgraded converter w/a converter clutch that's at least .050" thick. Also consider a billet cover if you're doing a lot of towing or otherwise live in a very hot, arid climate that sees temps north of 100 degrees. Pull the pan and take a look...If you see fine silvery looking material, that's converter..if you see small chunks of clutch material, that's likely converter clutch. If so (or if the fluid is really black and lots of clutch material on the bottom of the pan), I'd overhaul it while it's out for the rear main seal.

Is your cooler bypass valve still stock?

 

[gapost]

Yes, if that's the original JMBX factory converter, dump it and purchase an upgraded converter w/a converter clutch that's at least .050" thick. Also consider a billet cover if you're doing a lot of towing or otherwise live in a very hot, arid climate that sees temps north of 100 degrees. Pull the pan and take a look...If you see fine silvery looking material, that's converter..if you see small chunks of clutch material, that's likely converter clutch. If so (or if the fluid is really black and lots of clutch material on the bottom of the pan), I'd overhaul it while it's out for the rear main seal.

Is your cooler bypass valve still stock?

Thank you. No my bypass valve is the Superior one. I put it in when I bought the car about 5000 miles ago. So it’s probably too late. Any company recommendation for the TC?