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Again !!! My trans just went

73K5BlazerSS

73K5BlazerSS

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Driving home now and my work truck died. No power going through the trans. Feels like the torque converter, it shutters and looses power intermittently. I can smell it burning.

This is the 4th time it will need a new trans in 240k miles. Unbelievable... not a good time to happen at work.

I heard lots of people say that they've had good luck with the 6L90e. I swear this is the worst trans I've ever owned. The truck is a 2011 cab chassis with service body. It's weighs about 10k loaded up but it should be able to handle the weight it's rated for.

I'm gonna let it cool down and see if I can go 3.6 miles to the place that fixed it last. :sign29:
 
Bummer. I hope it gets you there. They’re not that bad of a trans, I’d be suspect of the work being done.
 
Still under warranty? Sounds like it might be shoddy workmanship vs an overloaded trans.

Is the converter still factory replacement or have you gotten any upgrade like a billet converter or full aftermarket?

Is the trans tuning still 100% factory? The factory torque converter lockup tuning is very weak
 
I got it there in a few stages, I had to wait for it to cool down periodically. I'm glad I didn't have to pay for a tow.

The 1st re build was a joke, lasted about 6k miles. The second rebuild was supposed to be covered by ATRA but the 1st trans shop wasn't paying their membership and just lied about being in the ATRA network.

So the 2nd time they put a billet torque converter in. That one lasted about 60 or 80k. That issue wasn't the TC apparently.
Then the 3rd time it got a complete remanufactured unit. Lasted about 60k and here I am again. Everything else on the truck has been great. Is it worth getting a Sonax TC? I doubt any remanufactured units come with these. So I'd have to have the shop swap them? I've read about them last night on the side of the road, I couldn't find any pricing.

I guess 10K might be fine for an occasional load, but not everyday. I think the reman warranty was something like 3/30k.
 
Unfortunately, it sounds like your transmission shop is part of the problem.

Maybe, a more reputable rebuilder would be in order?

Or, if it's a company vehicle just get a new one.
 
I found this post on another forum. Sounds like yours for sure. Do you keep it in tow/haul mode?

“We have several regular cab Dually's for work with the 6.0. They are used for towing and at roughly 110-130k we blew every single transmission on our 2011 trucks. We thought it might be related to the model year but just this week we had one go on a 2014 at 120k. They have all been well maintained so not sure if this is normal or if there is a problem when they are given heavy use for most of their life. We have a rep out inspecting the 2014 and hope they will step up to assist with the repairs. Up until they went out they worked great..As a personal use vehicle with just occational heavy use, they probably are probably are bullet proof. What GM needs to do is offer the Allison with the 6.0 as an option for those that use these trucks for commercial purposes.”
 
CT-BLAZER said:
Unfortunately, it sounds like your transmission shop is part of the problem.

Maybe, a more reputable rebuilder would be in order?

Or, if it's a company vehicle just get a new one.
Click to expand...
I've had it a 3 different shops.

I've been told by lots of people to forget having it rebuilt, and get a new remanufactured unit. Supposedly those have minor upgrades based off common failures.

I just bought a new pick up for the company. That wasn't cheap... nothing is. That's used for towing an excavator and larger stuff that won't fit inside our enclosed tool box body. I'd love to get a new one, unfortunately for that past 3 years business is nothing like it was for the previous 14 years.
 
Fastereddie said:
I found this post on another forum. Sounds like yours for sure. Do you keep it in tow/haul mode?

“We have several regular cab Dually's for work with the 6.0. They are used for towing and at roughly 110-130k we blew every single transmission on our 2011 trucks. We thought it might be related to the model year but just this week we had one go on a 2014 at 120k. They have all been well maintained so not sure if this is normal or if there is a problem when they are given heavy use for most of their life. We have a rep out inspecting the 2014 and hope they will step up to assist with the repairs. Up until they went out they worked great..As a personal use vehicle with just occational heavy use, they probably are probably are bullet proof. What GM needs to do is offer the Allison with the 6.0 as an option for those that use these trucks for commercial purposes.”
Click to expand...
Yea it seems like the torque converter size or design are not up to the 13k GVWR.

Maybe 10% or less the tow haul mode is used. Pretty much on bigger hills.

That's why I waited until 2024 to get our new pick up with the allison behind the 6.6 gas. Hopefully I can get 2 years out of the new remanufactured unit. The old shop truck is a 2006 sierra with 4L60e, and that has never given us any trouble. Time to let that one go due to rust. Granted it never pulled or carried as much weight regularly.
 
Last edited:
Maybe up date to a larger cooler. Just spitballing here, but if your heavy all the time, the factory cooler may not be big enough.

www.sonnax.com

GM 6L45/50, 6L80/90 No Movement Conditions | Sonnax

Learn common causes and diagnostic repair tips for 6L45, 6L50, 6L80, 6L90 transmission problems like no Forward, no Reverse and the abnormal pressure condition.
www.sonnax.com www.sonnax.com
 
Wes Harden said:
Maybe up date to a larger cooler. Just spitballing here, but if your heavy all the time, the factory cooler may not be big enough.

www.sonnax.com

GM 6L45/50, 6L80/90 No Movement Conditions | Sonnax

Learn common causes and diagnostic repair tips for 6L45, 6L50, 6L80, 6L90 transmission problems like no Forward, no Reverse and the abnormal pressure condition.
www.sonnax.com www.sonnax.com
Click to expand...
It's funny you mentioned that. The first time the torque converter failed the trans temp on the display was way up around 220. This time I thought it was just a trans leak because the temp was around 150. If I let it cool to 120 or less it would drive a few miles. It felt the same as the 1st time when the converter failed.

All I know is that this money should have gone to the blazer. It's been sitting for months.
 
The 6L80s suffer from what I call a fatal flaw in that the thermostat for the cooler sticks and the trans runs hot all the time, we were losing them left and right at work until we bypassed the factory cooler and thermostat. Trans that used to run 200-215 now run 160-180. Not sure if this affects 6L90s or not.
 
Fastereddie said:
I found this post on another forum. Sounds like yours for sure. Do you keep it in tow/haul mode?

“We have several regular cab Dually's for work with the 6.0. They are used for towing and at roughly 110-130k we blew every single transmission on our 2011 trucks. We thought it might be related to the model year but just this week we had one go on a 2014 at 120k. They have all been well maintained so not sure if this is normal or if there is a problem when they are given heavy use for most of their life. We have a rep out inspecting the 2014 and hope they will step up to assist with the repairs. Up until they went out they worked great..As a personal use vehicle with just occational heavy use, they probably are probably are bullet proof. What GM needs to do is offer the Allison with the 6.0 as an option for those that use these trucks for commercial purposes.”
Click to expand...
I was told the allison is not rated for the upper rpm range the 6.0LS runs its power band . Thats why there fine behind 8.1L & d-max . Not sure 100% true but would make sense.

I have also heads of these newer trans have a temp switch valve in cooler lines that likes to stick shut and COOK the fluid .

If my ask @Greg Ducato if he can do you one up and ship it .
 
him 6.6 can anyone say SBC 400?? going to have to look up the stroke on that.
 
Possibly a bigger truck..F550, F650, F750 would hold up better to the riggors you put your equipment through?
 
Do you use tow haul mode at all? It's like you're driving around hauling all the time. I'd bet adjusted shift points and pressures in the tune would help it last longer. Also some shops that install billet converters adjust the lock up to only be in 5th/6th. Did yours do that?

The factory tuning at least on the 1500s have it locking up in 2nd gear and shifting into 6th by 42 mph. That is ridiculous just driving an empty truck around let alone a loaded down one. It's purely done for gas mileage.
 
It's possible it would run some more with a new filter. Of course a plugged filter is most likely plugged with clutch material, so it's only a matter of time.

I think the pushbutton tow/haul selector is a mistake - in that you have to press it every time you start the vehicle. It should be a toggle switch. I think somebody makes a kit to make it work like that.

Does anybody know if the shift and pressure tables are different based on GVWR?
 
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