dbass

Hi,

I have a 99 Chevy Tahoe, pretty much all OEM parts, and recently it started producing a vibration that is felt through the steering wheel and the seats when stopped at say a light and in Drive. If I put it in Park or Neutral the vibration goes away and if I'm driving, it is not felt significantly. I had the dealer try to diagnose it, but they were at a loss. They thought maybe a fuel injection cleaning or a ignition cable replacement could help, but they couldn't say for sure.
I have this feeling that it could be related to the torque converter since I only feel it significantly when stopped in drive, which puts the transmission in a unique state. One other detail just to make it more confusing, the vibration is significantly stronger when the engine is warmed up, which is the opposite of what I would think it would be if it were a fuel injector problem, but not necessarily an ingnition problem.
Any thoughts?

in2pro

I would check the engine and transmission mounts... given the age its about right for them to start going out...

RacerX

Sounds like motor mounts to me. The rubber is probably cracked on all 3.

dbass

Thank you for the replies. I keep thinking it seems like the motor mounts and I asked the technician to check them visually. He says they look ok and that the engine doesn't bounce when you brake and press the accelerator at the same time, but it's possible that the plastic is so hard it's not dampening the vibration at all. No one has suggested to me that it might be the transmission mounts, so I can ask to have them take a look next time I'm there. It's a pretty frustrating problem because it's kind of spoiling the smooth ride of my Chevy when I'm riding around town.
Are there any other parts of the drive train that come under strain when in drive but not neutral that could cause a vibration like that. I know there are many, but I'm trying to think of one that might lock up more when the vehicle is in motion and maybe have more play to vibrate when the truck is stopped and in drive? The torque converter is the only part that I can think of that fits the bill, but there maybe others since I'm no car expert. Thanks.
One other note, I seem to be able to hear the vibration more towards the center and rear of the vehicle than the front by the motor when I walk around it while it's in drive with the e-brake on, but it may just be that the engine noise is masking it.

Twincycles

I had an exhaust pipe that caused a vibration one time and it turned out to be the exhaust balancer at the passenger side rear of the Tahoe, just in front of the rear wheel, put new balancer and vibration went away, never really understand why it corrected the vibration at idle but it did.

dbass

It could be some part of the exhaust system that is vibrating the vehicle. Since everything else has been checked, it's worth looking into that. Could you feel the vibration through the steering wheel?
Is the exhaust balancer in internal part of the muffler? Was it expensive to replace. It does seem like I can hear a resonance the same as the vibration coming from around the exhaust pipe. On that note, does anyone know how long a stock exhaust system lasts on a Tahoe. It's a '99 with about 70K miles. I am the original owner.

Twincycles

The balancer is on the outside of the exhaust pipe close to the muffler. I balancer replaced around 92000 miles.

I do not remeber the cost, you can just buy the balancer and either clamp to the pipe or spot weld it to the pipe.

Just info, I have 2 on my pipe currently, which I put on 4 years ago and 40,000 miles ago.

No problems since.

dbass

Ok. I had some really good guys check the exhaust system and they said the problem was not there but they could see and feel the engine vibrating. They thought it might be the torque converter or the crank shaft and referred me to a transmission shop. I called them and described the symptoms and the transmission guy felt it probably wasn't the torque converter since that would be felt when the engine was cold same as when it was warm and told me that the crank shafts rarely fail or go out of balance. He suggested I have the harmonic balancer checked. If that is bad, can it cause significant engine vibration?

73shark

It could if the rubber bonding the outer ring to the hub has failed.

Twincycles

Yep, just as 73 shark said if the rubber is cracked then it can cause vibration for sure.