K2xx Reliability, things to watch out for

[HeySkippyDog]

My uncle had the same gearbox in his Trailblazer and had it rebuilt twice and (as far as i know) didn't beat the piss out of it. His went about 120k if I remember correct. I just want to see if I should plan on a similar longevity for the 6L80E

[emoji848] are you sure? Where is he located approximately?

In FL, those 4L60Es will go for a long time as long as you're not on the coast with salt spray rotting everything.

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[NorthEast]

Like any large sampling, you might get one of the good ones out of the millions that have been sold over the last few years.  My personal experience sucks with this truck and it is especially terrible in traffic.  I found many examples of this issue in my searches, this link provides more examples.  

Of course, it is possible to milk 250,000 miles out of a transmission, but given my experience, I'll be shocked if mine passes 85k without serious work.

 

Good luck, hopefully you'll decide on a solid truck.

 

 

[gone_fishing]

I have 152,000 miles on my 14 Sierra and haven't had any major drivetrain issues (purchased new in Oct 13). Transmission shifts like it did when it was new. I have done a few drain/fills of the transmission fluid by extracting through dipstick. Did the filter around 130k. Valvline MaxLife ATF has been my fluid of choice.

 

Around 90k, I purchased a DiabloSport inTune i2 and installed their TCM and engine tune and turned AFM off. Most of my issues with the 6 speed aren't mechanical but in the factory computer tuning. The combination of torque management, heavy throttle/numb throttle, and the transmission wanting to be in overdrive ASAP make for a somewhat dismal driving experience. The transmission has been reliable but I think GM could have done a lot better job with the programming. The tune did help some with this but I think it still could be better.

 

Overall the truck has been good. Still have a light vibration around 75 MPH which is my biggest complaint. For anyone that is interested in purchasing a K2 series truck the first thing I would do would be to get it on the freeway and see if it vibrates at high speed. 

[Grumpy Bear]

24 minutes ago, gone_fishing said:

I have 152,000 miles on my 14 Sierra and haven't had any major drivetrain issues (purchased new in Oct 13). Transmission shifts like it did when it was new. I have done a few drain/fills of the transmission fluid by extracting through dipstick. Did the filter around 130k. Valvline MaxLife ATF has been my fluid of choice.

 

Around 90k, I purchased a DiabloSport inTune i2 and installed their TCM and engine tune and turned AFM off. Most of my issues with the 6 speed aren't mechanical but in the factory computer tuning. The combination of torque management, heavy throttle/numb throttle, and the transmission wanting to be in overdrive ASAP make for a somewhat dismal driving experience. The transmission has been reliable but I think GM could have done a lot better job with the programming. The tune did help some with this but I think it still could be better.

 

Overall the truck has been good. Still have a light vibration around 75 MPH which is my biggest complaint. For anyone that is interested in purchasing a K2 series truck the first thing I would do would be to get it on the freeway and see if it vibrates at high speed. 

This is a truck I watch carefully. He is proactive in his services and uses products anyone who owns a truck can afford. Most importantly to me, he's committed to this truck. He's realistic in his expectations and reasonable in the resolution of issues. Patient fellow that makes a solid data point worth the watch.  Hat's off gone-fishing! Solid input as always. Thanks. 

[Grumpy Bear]

10 hours ago, NorthEast said:

Like any large sampling, you might get one of the good ones out of the millions that have been sold over the last few years.

  

Of course, it is possible to milk 250,000 miles out of a transmission, but given my experience, I'll be shocked if mine passes 85k without serious work.

 

Good luck, hopefully you'll decide on a solid truck.

 

 

  So.....If I get a "one in a million' and 'milk it' like a Holstein it might make it to 85K? 

 

Bet you're fun in an intensive care ward. 

[diyer2]

If you don't get a lemon reliability lies in the hands of the owner IMO.

Do all services before severe duty intervals or at least severe duty intervals.

Don't abuse it.

 

In the 70's I had a small block with mods in a Nova that was a street rod and raced 1/4 mile in the summer.

It got ran hard,

Dino oil of course.

I never had an issue because I did great maintenance.