GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

1

Are any of the following noises heard: a sharp double knock when the engine is idling, a light ticking with no load on the engine, or a slapping noise when the engine is cold?

Go to Step 2

System OK

2

Inspect the piston pin and the bushing.

Is the piston pin or the bushing worn or loose?

Go to Piston, Connecting Rod, and Bearing Replacement

Go to Step 3

3

Inspect the piston.

Is the piston broken or cracked?

Go to Piston, Connecting Rod, and Bearing Replacement

Go to Step 4

4

Inspect the connecting rods.

Is there a misaligned connecting rod?

Go to Piston, Connecting Rod, and Bearing Replacement

Go to Step 5

5

Inspect the piston position.

Is the piston 180 degrees out of position?

Go to Piston, Connecting Rod, and Bearing Replacement

System OK