1983/12/21 Caterpillar

All Caterpillar-Built Truck Engines

Put a mark through the earlier article with the same title in the May 18, 1983, Truck Engine News and make reference to this article.

This new article has more complete information.

The "Guideline For Reusable Parts - Main And Connecting Rod Bearings ", Form 01, has information on the reusability of engine connecting rod and main bearings. This Guideline is also part of "Engine Bearings & Crankshafts", Form SEBD0531. On Page 3 of the Guideline is Caterpillar's recommendation for the reuse of bearings when a major overhaul is done. That recommendation is as follows:

"It is Caterpillar's recommendation that new bearings be installed when an engine is given a major overhaul (reconditioning).

Our recommendation is to reuse main and connecting rod bearings only when they are inspected as part of other service work on the engine. Some examples of when bearings might be inspected without doing an overhaul are as follows:

... Bearings are inspected to see if they were damaged by the failure of some other component.

... Bearings are inspected as part of a procedure to determine if an overhaul is needed.

... Bearings are removed when pistons are removed during an update or repair that is not a full in-frame overhaul, such as installation of new rings or pistons.

When bearings are inspected, as in the above examples, it is possible that some of the bearings will have early wear or damage. The remainder of the bearings can normally be used again if there is no other reason to do a full overhaul. Do not make a replacement of bearings at inspections if they show signs of light or normal wear.

Only use the "Guideline For Reusable Parts" when bearings are inspected as part of other service work on the engine. We do not recommend that bearings be used again when the engine is expected to be operated for another full major overhaul interval. (Of course, bearings that have been used only a few hours and have normal wear can be reused.)

When bearings are used again, always be sure they are installed in the same locations (against the same journals) as they were originally. Make sure they are not damaged when they are cleaned or handled. Never reuse bearings with a different crankshaft, or with a crankshaft that has been turned end-for-end (direction of crankshaft rotation has been changed). If a crankshaft journal is polished, install a new bearing on that journal. If a new connecting rod is used or if the large bore is reconditioned, always use a new bearing.

Regardless of whether new or original bearings are installed, always check the original bearings for any unusual wear. Be sure to inspect the connecting rods and caps, the crankshaft, and the bearing bores in the block, whenever it is possible that they may cause a bearing problem or there is unusual wear.