1. Grinding or screeching noises in the area of the accessory drive

A serious grinding or screeching noise in the accessory drive usually means that the one or both of the roller bearings in the drive have failed. The usual bearing to fail is the one directly behind the pulley that drives the alternator.

There is a report of accessory drive bearing failures in the tech tips section of our web site giving additional background information, but basically, the only remedial action is to remove the accessory drive and replace the bearing or bearings. If you want to confirm that the accessory drive is the real problem, you can press against the pulley with a small piece of wood to impose a slight side load on the bearing. If the bearing is bad, the noise will usually alter significantly, either getting louder or sometimes softer. In either case, you can be quite sure that the bearing is in trouble. Obviously, this check assumes that you have sufficient access to the accessory drive and, more importantly, that you can perform the check safely. - Updated: November 4, 2003