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?

 

[NickTransmissions]

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?

Circle D, Florida TC, TCI come to mind. Also look into the Camaro ZL1 converter from GM.

 

[gapost]

Circle D, Florida TC, TCI come to mind. Also look into the Camaro ZL1 converter from GM.

Thank you!

I pulled the pan today. Yes the fluid was dirty, I wouldn't say burnt. The magnet was full of very fine metal. However, there wasn't really metal particles in the pan. I cut open the filter and there were some small metal particles in there. Can't say if it was a lot as I never cut open a filter. But I would say it was doing it's job. For 122,000 miles, with probably no service, I would say it looked pretty good and I would think the transmission is ok. So now will get a TC and install that and hope for the best. Thank you for the help Nick.

BTW, on this 2019 Tahoe, I was able to get the pan off without jacking, pulling or removing the exhaust. I pulled the filter off and out before trying to pivot the pan out and don't forget to pull the dipstick.

 

[Thrust]

Circle D, Florida TC, TCI come to mind. Also look into the Camaro ZL1 converter from GM.

The ZL1 converter a decent option compared to Circle D and the others? I was looking at the Circle D 300mm and was trying to justify why it's so much more than the ZL1. Thoughts?

 

[NickTransmissions]

The ZL1 converter a decent option compared to Circle D and the others? I was looking at the Circle D 300mm and was trying to justify why it's so much more than the ZL1. Thoughts?

The Circle D uses a triple disc set up and billet front cover, which accounts for the difference. The ZL1 is a good option over stock but any competent converter builder can build you what you want for less.

Circle D

 

[NickTransmissions]

Thank you!

I pulled the pan today. Yes the fluid was dirty, I wouldn't say burnt. The magnet was full of very fine metal. However, there wasn't really metal particles in the pan. I cut open the filter and there were some small metal particles in there. Can't say if it was a lot as I never cut open a filter. But I would say it was doing it's job. For 122,000 miles, with probably no service, I would say it looked pretty good and I would think the transmission is ok. So now will get a TC and install that and hope for the best. Thank you for the help Nick.

BTW, on this 2019 Tahoe, I was able to get the pan off without jacking, pulling or removing the exhaust. I pulled the filter off and out before trying to pivot the pan out and don't forget to pull the dipstick.

You're welcome, @gapost . The fine metal is likely bushing material flaking off (normal) as the factory bushings are silver in color or minute amounts of clutch material from all the clutch packs (normal wear).

 

[gapost]

You're welcome, @gapost . The fine metal is likely bushing material flaking off (normal) as the factory bushings are silver in color or minute amounts of clutch material from all the clutch packs (normal wear).

Well hopefully just replacing the TC will keep it going for many miles. I'll keep you updated. Thanks again.

 

[gapost]

You're welcome, @gapost . The fine metal is likely bushing material flaking off (normal) as the factory bushings are silver in color or minute amounts of clutch material from all the clutch packs (normal wear).

Nick I drove about 50 miles since changing the fluid and filter. I got my TC from Florida TC (great service btw) and was going to pull the tranny and just replace the converter. I cut open the filter and found small metal particles and don't feel good about just putting in the TC. I'm going to get a GM Reman. One question. That should have the updated thermal bypass so I don't need to use my old one, correct?

 

[NickTransmissions]

Nick I drove about 50 miles since changing the fluid and filter. I got my TC from Florida TC (great service btw) and was going to pull the tranny and just replace the converter. I cut open the filter and found small metal particles and don't feel good about just putting in the TC. I'm going to get a GM Reman. One question. That should have the updated thermal bypass so I don't need to use my old one, correct?

Check with GM before tossing your eixsting valve or replace it as well, esp if metal potentially passed through it. The valve is always removed prior to the transmission arriving at my shop.

ETA: did you take any pics of the filter and metal bits? If so, post a couple - curious to see what you found.

 

[gapost]

Check with GM before tossing your eixsting valve or replace it as well, esp if metal potentially passed through it. The valve is always removed prior to the transmission arriving at my shop.

ETA: did you take any pics of the filter and metal bits? If so, post a couple - curious to see what you found.

Kind of hard to see the silver particles as they are all pretty small. But this is only like about 50 miles. There are really small silver particles all throughout.

 

[NickTransmissions]

View attachment 401088View attachment 401089View attachment 401090
Kind of hard to see the silver particles as they are all pretty small. But this is only like about 50 miles. There are really small silver particles all throughout.

Good call on replacement, pic is worth a 1000 words...looks like torque converter was/is starting to fail (shocker, lol). Was thinking you were seeing very small flaky material which is usually bushings just wearing down as time goes by.