5.3/3.42/6sp Complaints

cgunderson77 · October 22, 2011

I have a 2009 GMC with the 6sp/3.42 and HATE it! It does the lunge forward thing like other posts speak of, it "clunks" in the lower gears, it shifts erratic at all temperatures, and it is a dog with the lag time between pedal movement and when it actually starts moving. I just had it in the GM shop today for an oil change and told them about the transmission "issues". First thing they ask...."do you have any trouble lights?". I reply no, and at which time, they basically think nothing is wrong (there are no mechanics in the world anymore, if the computer says everything is fine, it must be fine.). Anyway, they "look" at it and test drive it, and tell me nothing is wrong with it. Sorry, but there IS something wrong with it.

cjbondra · October 22, 2011

There are definately bad apples. I had a 2004 blazer that had a major issue in between every oil change. I bought it used with 38K miles. I traded it back after two years with 58K miles. I only bought it because I did not want to give up my 1990 Chevy Cheyenne standard cab. I traded it in along with my 1990 because I just couldn't afford to keep fixing it and my 1990 truck needed some work. I love my new 2010 1500 Silverado. One year old and only had to have a coolant hose nipple fixed under warrenty. I do hate that my daughters can't sit in the front seat because the airbag may decapitate them. My daughter loved sitting in the front of my old truck. I'd still have the truck if it wasn't for my piece of junk Blazer. But I know not all Blazers are bad because I still see them everywhere. Mine was the bad apple.

AlaskanSilverado07 · October 22, 2011

I have a 2009 GMC with the 6sp/3.42 and HATE it! It does the lunge forward thing like other posts speak of, it "clunks" in the lower gears, it shifts erratic at all temperatures, and it is a dog with the lag time between pedal movement and when it actually starts moving. I just had it in the GM shop today for an oil change and told them about the transmission "issues". First thing they ask...."do you have any trouble lights?". I reply no, and at which time, they basically think nothing is wrong (there are no mechanics in the world anymore, if the computer says everything is fine, it must be fine.). Anyway, they "look" at it and test drive it, and tell me nothing is wrong with it. Sorry, but there IS something wrong with it.

Yes, this has been a problem for me too. I even received a call from GM corporate inquiring about my concerns. They said it was noted on my survey and they wanted to follow up on it. I explained my concerns and they stated an "engineer" will contact me to discuss the issue. I'm pretty sure I'll get that call right after Ed McMahon calls with my winning $8MM check but until then I've learned from some of the guys on here to run it around town in M4 and this works well. I'm still not a fan of the 6-speed transmission and had I know this is how it would work I would have kept my 2009 as that 6-speed worked fantastic especially towing a trailer from Anchorage, Alaska to Houston, Texas. Obviously not all of them are bad but it seems I drew a dud on this one...

nyplumber · October 22, 2011

I just got mine 1500 z71 5.3 six speed with 3.42. The day I picked mine up from dealer I switched from 3.08 to 3.42 glad I did. So far love the truck! What is the 6l80E that I see people puting down next to size motor?

Wires · October 22, 2011

I have a 2009 GMC with the 6sp/3.42 and HATE it! It does the lunge forward thing like other posts speak of, it "clunks" in the lower gears, it shifts erratic at all temperatures, and it is a dog with the lag time between pedal movement and when it actually starts moving. I just had it in the GM shop today for an oil change and told them about the transmission "issues". First thing they ask...."do you have any trouble lights?". I reply no, and at which time, they basically think nothing is wrong (there are no mechanics in the world anymore, if the computer says everything is fine, it must be fine.). Anyway, they "look" at it and test drive it, and tell me nothing is wrong with it. Sorry, but there IS something wrong with it.

That's torque management and the TCM programming. Really not an issue of the tranny, but the programming the TCM. If you get a tune, all those issues magically go away, and it works/shifts as expected. Put a Westers tune in my PCM & TCM and never looked back.

music · October 22, 2011

What is the 6l80E that I see people puting down next to size motor?

Model Numbers

Light duty 6-spd: 6L80e

HD 6spd: 6L90e

Light duty 4spd: 4L60/65/70e

HD 4spd: 4L80/85e

MikeNH · October 22, 2011

Mine will be stupid if I keep it in drive around town. The 6 speed is fantastic on the highway, esp given how hilly the northeast is. In my '03 going up to Vermont with my parents it'd be pulling some of the hills in 2nd and be screaming because there was such a big gap between gears on the 4L60. This truck does much nicer. But in town it's in too much of a hurry to make 6th and the truck will bog and shift at the slightest application of throttle. Can't really fault GM for this, their hand was forced along with the other guys to get better fuel efficiency ratings. So like has been mentioned, my truck is always in manual mode- in town I'm in M4, running 35-45, outskirts of town I'll go up to M5 and up to 55 MPH then finally if I'm on the highway, M6. It should also be noted that AFM is disabled in all manual gears but M6, so no AFM cycling in town. Even on the highway it's not on often because of the constant slight grades. This driving style most certainly costs me some fuel efficiency but it's worth it to me to have the truck have power immediately and not need to drop a gear or 2 in town.

Z45 · October 22, 2011

2010 5.3L, 6-sp, 3,42 G80

No transmission problems, no clunks, nothing, about 15,500 miles in 1.5 yrs. The only problems I have is he tire pressure monitors system, its throws out random high air pressure readings (70psi) every now and then and service TPS. Dealer recalibrated TPS with tool but still an occasional high reading that moves from wheel to wheel. Once it was there for 4 days until the dealer looked and it was normal.

One thing I do know, it takes some getting use to driving a 6sp and if are a driver who hot rods a little, the trans will be shifting constantly trying to keep up with your driving style and that may account for lots of complaints on clunks, lunging etc.. There is only one reason the 6-sp exists and that is for fuel economy. Things are going to get a lot worse with trucks trying to make the 25.5 mpg fuel economy standards by 2014 +-. for trucks.

Wires · October 22, 2011

There is only one reason the 6-sp exists and that is for fuel economy.

More gears = more performance and more MPG. Isn't not just about MPG. Any GM tranny (4 speed is really bad for this) has wide, equally spaced gear ratios. You get between gears, and the truck is gutless.

If you hop into a Ford, they keep the lower gears at a tighter ratio, so around town, it's a lot nicer to drive. But then the gap to higher gears is really large, so it's a PITA on hilling roads. My 5 speed Mustang was BRUTAL. 4th raced the engine, 5th lugged it.

More gears is the reason the CVT transmission is the optimal choice for power delivery. You can keep the engine in it's power sweet spot. Problem with the CVT is under any load, it's up in high RPM's working the magic, so people don't like the racing engine.

skeeter55 · October 23, 2011

I have a 2011 Silverado, Texas Edition. 5.3, 6 sp, and I am not happy with the gas mileage. The

engine on mine does have some lag on acceleration. I haven't punched it but a few times.

I was told that the transmission would "learn" my driving style, I will say it has stopped shifting

so much on upgrades.

I think mostly you learn how the truck operates, and drive it a little differently.

My prior ride was a 2001 GMC and I liked it.

My $.02.

AlaskanSilverado07 · October 23, 2011

I have a 2011 Silverado, Texas Edition. 5.3, 6 sp, and I am not happy with the gas mileage. The
engine on mine does have some lag on acceleration. I haven't punched it but a few times.

I was told that the transmission would "learn" my driving style, I will say it has stopped shifting

so much on upgrades.

I think mostly you learn how the truck operates, and drive it a little differently.

My prior ride was a 2001 GMC and I liked it.

My $.02.

If it's learning my driving style, then its working as it learned how to piss me off and proved to me that it rode the short bus to school.

Wires · October 23, 2011

I have a 2011 Silverado, Texas Edition. 5.3, 6 sp, and I am not happy with the gas mileage.

The 6 speed isn't going to give drastically better mileage than the 4 speed. On level ground, and no wind, the 4speed = 6speed in MPG.

Where the 6 speed shines is it gives you the 3.5 gear between the 3rd and 4th gear in the 4 speed. So under load (hills, winds, etc), it doesn't need to do a ratical downshift that burns more fuel. (My 4speed used to jump from 2000RPM to 3000RPM and then you could watch the gas gauge drop).

The common misconception is "If I get the 6speed, I'm going to get amazing mileage". That isn't the case at steady state cruise on flat conditions. It's still the same engine with the same final drive, so the same RPM's on the tach, so same MPG.

uh6tdrvr · October 24, 2011

I had a shift flare 2-3 and the dealer replaced the pump seal I think, all new fluid and a transmission reflash and its shifts alot better now. As far as no V4 in M mode, imma have to check again but I think it goes into V4 in all modes.

music · October 24, 2011

As far as no V4 in M mode, imma have to check again but I think it goes into V4 in all modes.

Curious to hear. AFM is only enabled in "D" on the 4-spd.

LT1MCSS · October 24, 2011

I put up a post last week about the 4sp vs 6sp. Originally I only wanted the 6sp mainly for the fuel economy. I would say 50% of my driving is city and the other 50% is on the highway. Of the 50% on the highway 25% of that is in stop and go traffic at 35mph or less. I doubt with my current driving i would see little difference in the 4sp and 6sp. I am just thinking further down the road as this will more than likely be a truck i have for a while. If I find myself dirving on the highway more I may get better use out of the 6 speed plus it is newer. My current truck is a 6.0/4L80E and I have never had a problem. I know a bunch of people with the 5.3/4sp combo and they have never had a problem. I know one person with 1 6.2/6sp and they are very very picky and they haven't complained. The only thing they did say was get the 3.42's.

After reading some of the posts with the 6speed though it seems the majority of people are happy but some people really hate it. I know supposedly there is a computer update for it that makes the problems people are talking about better. The problems I have read about definitely have me double thinking the 6speed but I think I am still going to go with it.