| Subject: | Information on 4.3L Engine Front Crankshaft Pulley Appearing to Be Out of Round (Normal Condition) |
| Models: | 2005-2006 Chevrolet Silverado 1500 Series |
| 2005-2006 GMC Sierra 1500 Series |
| with 4.3L Vortec V6 Engine (VIN X -- RPO LU3) |
This bulletin is being published to aid the dealership when explaining to the customer that the crankshaft pulley appearing to be out of round is a normal condition. The Silverado and Sierra 1500 series pickup trucks started using an electric fan for the
2005 and 2006 model years with the 4.3L Vortec V6 (RPO LU3) engine. As a result, the shroud was removed and the front crankshaft pulley is now visible. This type of pulley arrangement has been used for several years and has been checked and found to be within
specification.
The customer perception is further intensified by a white paint dot that is placed on the pulley that is used to align the pulley in the vehicle assembly plant. When the vehicle is running, this paint dot creates the illusion that the pulley is not rotating
in a circle.
This is a normal condition and the crankshaft pulley does not have to be replaced.
