Hello! I have a 2018 Chevy Tahoe Premier RST 6.2L. Initially brought it into the dealership because the front end would click when turning my wheels to the right. Found out i needed the sway bar links replaced because they were broken. The dealer also recommend I replace the left engine mount because it was bad and i decided to do it since my truck was already there. Here is where the fun starts, I go to pick up the vehicle when the repairs were made and when i went to start it and leave the entire truck was shaking at idle and whenever i would stop or put it in park. I ended up turning back around and told them my truck wasn't idling like this when i initially brought it in. They said that it could possibly be the other motor and transmission mount causing the issue because there is a new one and place and there may be play in the other ones. I agreed to let them replace those as well (they discounted some of the labor on it) but the truck still has a really rough idle. They told me they touched nothing on the engine in replacing the motor mounts and since i have 80000 miles on it that it is probably carbon build up in the engine and it's just pure coincidence that it started around the same time that they replaced the motor mount. There is no check engine light on, no misfires or anything coming off the computer (I was thinking maybe it was a sparkplug, or sparkplug wire). They suggested i run a 5-in-1 fuel system cleaner through the system during my next fuel up and hope that it resolves the problem. I tried 2 different brands on each fill up and it still idles like crap. I'm at my wits end right now, had a truck that ran great before bringing it in and now it runs like a truck from the 1970s. I'm somewhat reluctant to bring it back because i keep having to pay for things the replace hoping it will fix the problem. Can anyone provide any advice on other things i could try? I'm also contemplating reaching out to GM directly.

 

And the service tech never noticed this when he drove it in test drive or just to the parking lot???


Sounds like dealer wants to keep guessing with your money. I'd contact GM regional or corporate.

 

Yeah the service advisor even commented that it didn’t feel right after I came back to complain. I’m probably just going to reach out to GM directly. Does anyone have an idea what could be causing the issue?

 

It's a 2018, have they bothered to hook it up to their fancy computers and actually see what the problem(s) are - and at this point if not, please run to a reputable mechanic.

 

They did. No check engine light and the computers showed nothing. No misfires either. They told me they opened a case with GM engineering to see what else they could do.

 

Most likely related what was just done - like the replacement of the motor mount.

 

So a faulty motor mount was installed? I also found this technical bulletin doing research on my own. Wonder if this could be related? I’m trying to arm myself with as much info before I go to GM. The dealer wants to keep replacing various things each time I go in with no guarantee it will fix the issue. It’s so frustrating.

https://static.nhtsa.gov/odi/tsbs/20...66640-9999.pdf

 

Interesting find, Ray !

 

Just wanted to update the thread in case anyone else encounters a similar issue.

Opened a case with GM Corporate and CC'd the CEO Mary Barra, shortly after i talked to someone from the corporate office who handled communications with the dealership. Come to find out they installed an aftermarket motor mount on my truck causing the problem....it should have been replaced with an OEM motor mount which contains hydraulic fluid and dampens the engine movement. Once it was replaced my truck went back to idling smoothly just like it did when i first owned it. Stay far away from any aftermarket motor mounts on the 6.2L and shame on the dealer for putting an aftermarket part on my vehicle initially....i could understand if it was a private mechanic but not at a GMC/Chevy dealership.

 

Winner, winner; chicken dinner !!!!

Maybe the GM part was on backorder so to get customer "out of the dealership" they installed a substandard part. Note that GM itself doesn't make motor mounts, contracts for them.