2002 GMC Envoy PISTON SLAP

KEYMAN

MEMBER
2002 GMC ENVOY
6 CYL
4WD
AUTOMATIC
106,000 MILES

Last weekend I drove my truck and upon arriving at my destination I heard a subtle "clicking" noise. It sounded like my lifters. I checked my oil level, which was fine. On Monday, I drove the truck a few blocks and the noise became very loud "clicking and knocking". I have researched the symptom online and found that "piston slapping" is common for GM vehicles between 98-2003 due to engine building practices. Although GM has called this symptom as "normal", they went back to matching pistons to cylinders in 2004.

Are you aware of any recourse through GM to have this problem fixed due to poor workmanship?

The car was idling rough, so I thought maybe it has a bad oxygen sensor.

Can a bad oxygen sensor cause these bad noises?

Thank you in advance for your support.

1 Reply

BRIAN 1

MECHANIC
1,030 POSTS

Most common on the 4.2L was the cylinder liners(sleeves) comming loose out of the engine block. This was a real big problem in 02 and 03 model years. The engine block is aluminum and the liners were cast iron and they were not pressed in properly causeing the cylinder to move up/down in the bore. 02 was the worst year for this problem, replaced afew engines in these vehicles.I would check a little more into the knocking sound to make sure what type of problem your having.