6.2 motor blown with 60,000 miles????

Robert Semas · January 28, 2020

I have a 2014 GMC Sierra 1500 which I bought in April 2015 as a certified pre-owned (15,000 miles) At 40,000 miles it began throwing misfire codes and the dealer ended up replacing all the injectors. Recently at 60,000 miles, the check engine light began to flash and the traction control error light came on. Took it to a local shop which diagnosed the #1 cylinder has over 32,000 misfires and the piston had a hole in it. They confirmed I had not broken a valve or spring.

Come to find out, I was 3 months past the 5 year power train warranty. GM is offering some assistance with the repair, which will be a new motor. I'm still going out about $4,500 and the dealer can't tell me why the motor had the failure.

I suspect this has been a problem with these motors, because everyone I have spoken to does not seem surprised. Anyone else have this type of problem? Any thoughts of what could have caused the motor to fail?

CamGTP · January 28, 2020

If the piston was the only damage, a new piston would have been cheaper but dealerships don't really roll that way when it comes to warranty or assistants.

Dropping a valve or having a broken valve springs is only really common on 2014-2015 truck because they switched springs around 2016 if I remember right but the number of those failures is still really low. Having misfires and issues from lifters or an injector failure is more common and that can happen on any of the engines no matter what year.

Without seeing the engine with the cylinder head off I can't really guess at what may have causing a hole in the piston. Maybe the injector tip broke off and went through it. Or the piston just cracked and broke itself.

njk4o5 · January 28, 2020

years ago i had a hole in the top of my snowmobile piston from water ingestion riding through powdery snow. could maybe be water in the gas?

truckguy82 · February 1, 2020

On 1/27/2020 at 9:37 PM, Robert Semas said:

I have a 2014 GMC Sierra 1500 which I bought in April 2015 as a certified pre-owned (15,000 miles) At 40,000 miles it began throwing misfire codes and the dealer ended up replacing all the injectors. Recently at 60,000 miles, the check engine light began to flash and the traction control error light came on. Took it to a local shop which diagnosed the #1 cylinder has over 32,000 misfires and the piston had a hole in it. They confirmed I had not broken a valve or spring.

Come to find out, I was 3 months past the 5 year power train warranty. GM is offering some assistance with the repair, which will be a new motor. I'm still going out about $4,500 and the dealer can't tell me why the motor had the failure.

I suspect this has been a problem with these motors, because everyone I have spoken to does not seem surprised. Anyone else have this type of problem? Any thoughts of what could have caused the motor to fail?

Were you running it on 87?

Josh_PNW · September 12, 2020

My 2014 6.2L Sierra just blew a piston at 102,00...just out of warranty! No help from GM . Still not sure what caused it but maybe during the replacement someone will dive in and try and see.

flyingfool · September 18, 2020

you do have a direct injector operating at 1000-2000 psi in there... possible its could shoot high velocity fuel at the pistion if there is a hicup on the AFM on/off sequence?? maybe its sprayed the piston at TDC durring those 32,000 misfires?

yet another reason to run your truck in 4th or 5th gear to deactivate the AFM until you need it on the highway

Edited September 18, 2020 by flyingfool

Grumpy Bear · September 18, 2020

Given the melting point of aluminum 'misfire' in this case I would guess means "detonation"/"preignition". 32K misfires and you felt or heard nothing? Just say' n. Around 15% a misfire is obnoxious. A dead cylinder is 13%. That's about 40 minutes of OMG what the **** is going on!!!

Edited September 18, 2020 by Grumpy Bear