DIESEL - MAIN BEARING CAP BOLT APPLICATIONS

There are two different length main bearing cap-to-block bolts being used in production. An engine will have only one length cap bolt; there is no mixing of bolt types. Bolt length is measured from the bottom of the bolt head to the end of the threaded part of the bolt.

One type of cap bolt is 100 mm (3 15/16") long. It is used on engines that have main bearing caps that have their location in the engine cast into the cap, i.e. 3 = number three main bearing cap.

The other type of cap bolt is 110 mm (4 11/32") long. It is used on engines that have main bearing caps that have their location in the engine identi- fied by the number of raised ribs cast into the cap (see illustration).

Using a long bolt where a shorter length is required will cause the bolt to bottom out before the bolt is contacting the main bearing cap. Using a shorter main bearing cap bolt than required will reduce the amount of thread engagement. This will cause the block threads to strip.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.