K2xx Reliability, things to watch out for

Giants2610 · September 29, 2019

Hey guys,

Looking at buying a 2017 or 2018 Silverado 1500, most likely a lower level trim (LT, LS, Custom). Just have a few questions:

I've heard that the eight speed transmissions tend to be pretty spotty in terms of reliability, can anyone confirm that? How is the 6 speed compared to it ?

I've heard that the new 4.3 V6 is comparable to the old 4.8 in terms of power, what do you think? How's it compare to the 5.3 ?

Anything you notice that's a real problem on these trucks, even though they're still pretty new ?

What should I be looking at when I head to the dealer ?

HeySkippyDog · September 29, 2019

You are right about the 8 speed. There seems to be a fix that involves changing to a different torque converter, but it does not seem to be 100%. The 6 speed will need regular fluid and filter changes to keep from being a problem. 75,000 miles per change is about the rule of thumb.

The Ecotec 4.3 is 10 HP shy of a Vortec 5.3, so in that regard, it is more powerful than the old 4.8. The 5.3 Ecotec of today is pretty good. Fuel economy is really not much different than the 4.3. I think your best value is going to be a 5.3.

Don't get painted bumpers unless you like fixing rock chips.

You'll get a lot better, smoother performance out of the truck by disabling V4 mode. You can do this with a plug-in device. It's reversible if you don't like using it.

Other than that, there's really not a whole lot wrong with them.

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Grumpy Bear · September 29, 2019

I like, no, love my 4.3 and 6 speed. Been pretty trouble free for 100K miles. Pinion seal to date. I do maintain it much better than the GM manual. Better than even the GM severe service schedule. The 4.3 is both economical, if adult driven and powerful enough for the RCSB I own so that a V8 would be overkill at this weight and the engines state of tune.

HeySkippyDog · September 30, 2019

I like, no, love my 4.3 and 6 speed. Been pretty trouble free for 100K miles. Pinion seal to date. I do maintain it much better than the GM manual. Better than even the GM severe service schedule. The 4.3 is both economical, if adult driven and powerful enough for the RCSB I own so that a V8 would be overkill at this weight and the engines state of tune.

Agreed, the 4.3 is probably all you'd want in a RCSB.

With the locking rear diffs in these trucks that can lock at very inopportune times, I once slung my 5.3 double cab 180 degrees around in the rain from a stop sign trying to make a wide left turn. I didn't goose it, it locked the rear over a thick painted line and suddenly it was like ice.

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NorthEast · September 30, 2019

My 2017 4x4 4.3 double cab just hit 36k. Heres my input:

The GOOD

-The engine is 2 ticks better than adequate. Id give it a 7.3 out of 10.

-Fuel efficiency is great. 19.5 mpg in mostly town driving in L5 (V4 and 6th gear disabled). About 22 mpg with V4 and 6th gear enabled).

-Well equipped with goodies like htd mirrors, android auto, and projector headlamps are great on a work truck.

-Great visibility, excellent highway cruiser, ----Forward hinged extended cab doors

8.7/10 for exterior styling

-The heating system gets ridiculously hot in the winter.

-Even with crap tires, it is a beast in the snow.

The BAD

The 6 speed consistently exhibits

garbage-esque characteristics: clunking, jerking, bucking, slow reverse to drive transition. (L5 helps a little).

-V4 mode shudders at 37 to 39 mph, rumble strip sensation (as a result I disable it).

-2nd gear saps most acceleration due to its relatively high ratio compared to first (4.03 to 2.36 falls off a cliff)

The MEDIOCRE:

-The frame is coated in wax. A couple areas require annual abrasive surface rust removal and recoats (1 hr with the daubert nox rust can)

-The leaf springs are noisy when reversing at low speeds. They clunk (probably due to excess play in the bushings)

-The front suspension has VERY limited down travel due to a UCA bumpstop. On rough roads, it SLAMs into potholes.

-On my WT trim, the factory speakers produce poor sound quality.

-The rear seat headrests do not stay in their raised setting-one finger can push them back down.

-low hanging front air dam

My VERDICT:

-Take your prospective truck on a long test drive in suburban traffic. Hustle it, get on and off the gas up and down hills

-Shift from reverse to drive and check the response time, check and smell the trans fluid.

-If you buy one, opt for an extended powertrain warranty

-Check the frame for any bare rust and ask the dealer to strip the affected zones and spray with noxrust.

I documented my truck's transmission issues with the dealer. They handed me a TSB that describes the clunkiness as normal operating behavior due to "many moving parts". I plan to regularly document the issue to build a trail of evidence. It's still under warranty and I don't beat on it. I'll probably bring it in for some deep evaluation before 60,000 miles to get it sorted or replaced.

My previous truck was a 2010 Frontier that I beat the hell out of up to 130,000 miles with zero unscheduled maintenance issues. If this truck's transmission fails, I'll get a new Titan.

CamGTP · September 30, 2019

The 6L80e has been my favorite transmission to date, on my 3rd truck with it. I will admit that me having access to a tuner and not having to worry about warranty has allowed me to "fix" or change the way it functions so never develops some of the issues that could happen. Being that that is not a option for everyone I still think it's better transmission that the 8L90e.

Even my parents have bought a 2012 and now a 2016 with the same transmission, both have been completely stock and so far no issues or complaints from my mother that drives it everyday.

Giants2610 · September 30, 2019

Do the 6L80s generally crap out at the 100-120k mark like the 4L60 did?

CamGTP · September 30, 2019

From what I've seen, no not really. I had 110k on my previous truck, was still as crisp as ever. My current truck has 100k, no signs of anything wrong.

In the end it's the luck of the draw but I tend to read for more stories of them being at much higher mileage before something happens. Random example, my previous boss has a 6.2 escalade, the 6L80e died at almost 200k. Installed a new GM unit with some crazy warranty and still trucking.

Bohanan23 · October 1, 2019

Currently love my 2014 with 5.3/6l80e. Only thing I would like to have is a 6.2 and 8 speed. Without the issues, the 8 speed is a solid transmission. No issues with my 6l80e. Only small things I don't like about mine is the small random noises the truck makes. Like passenger seat and small things. That's nit picking but that's how I am naturally with my vehicles.

Bohanan23 · October 1, 2019

BTW, comparing a 4l60e to a 6l80e is the farthest comparison. Had no issues with even my 4l60e after a converter change. 6l80e can hold 7-800+ with ease with a good cooler and tune.

Grumpy Bear · October 2, 2019

On 9/29/2019 at 10:34 PM, Giants2610 said:

Do the 6L80s generally crap out at the 100-120k mark like the 4L60 did?

Not aware the 4L60 was a problem unless abused or neglected. Ditto the 6L80/90E. Seen many of both go well past a quarter million with rational service and adult supervision.

mookdoc6 · October 2, 2019

22 minutes ago, Grumpy Bear said:

Not aware the 4L60 was a problem unless abused or neglected. Ditto the 6L80/90E. Seen many of both go well past a quarter million with rational service and adult supervision.

At the time they were far better than Ferd or Chrysler's offerings it was not until the 4L60E was designed that baby was ROCK! Anyway after that my 6,8 speeds have all been way to complex and goofy...the 4L60E's yeah they nailed that puppy! Too much Chit going on with Trans nowadays imo. Just give me a massive CVT for a truck that will not break and I will be fine with that!

Grumpy Bear · October 2, 2019

Mook are not the 4L60E and 4T65E basically the same box guts and brain?

HeySkippyDog · October 2, 2019

Not aware the 4L60 was a problem unless abused or neglected. Ditto the 6L80/90E. Seen many of both go well past a quarter million with rational service and adult supervision.

My experience has been this as well.

Most issues you hear of 4L60Es are on lifted trucks. On factory sized wheels and tires? No problem.

6L80Es seem pretty good to me as well. 6 speeds is a lot nicer for highway driving than 4.

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Giants2610 · October 3, 2019

3 hours ago, HeySkippyDog said:

My experience has been this as well.

Most issues you hear of 4L60Es are on lifted trucks. On factory sized wheels and tires? No problem.

6L80Es seem pretty good to me as well. 6 speeds is a lot nicer for highway driving than 4.

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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