Connecting Rod Bearings Caterpillar

Connecting Rod Bearings

Usage:

ENGINES

COMPACTORS

MOTOR GRADERS

OFF-HIGHWAY TRUCKS

ARTICULATED TRUCKS

TRACK-TYPE TRACTORS

TRACK LOADERS

WHEEL LOADERS

WHEEL-TRACTOR SCRAPERS

EXCAVATORS

PAVING PRODUCTS

PIPELAYERS

SKIDDERS

AGRICULTURAL TRACTORS

3400 ENGINES IN ALL APPLICATIONS, 3300 ENGINES IN ALL APPLICATIONS, 3176 AND C-10 ENGINES IN ALL APPLICATIONS)

Problem:

Some connecting rod bearings, manufactured during July through December of 1999, have been found to have Lead/Tin Overlay (LTO) flaking or "sheeting". These connecting rod bearings were used in the 3300, 3400, and C-10 production engine families between October 1999 and March 2000. These connecting rod bearings were also present in the Cat parts system from October 1999 through August 2000. This condition has been found in the following ways:

* From Scheduled Oil Sampling (S·O·S) with high Lead readings

* Large LTO flakes observed in the oil filter

* During other engine repairs or inspections

Most connecting rod bearing flaking or "sheeting" reports are seen within the first 3 or 4 oil changes on the engine.

It should be noted that the manufacturing process for these copper bonded connecting rod bearings could produce LTO flakes without any detrimental bearing performance. Extensive engine testing and field review indicates that these LTO flakes are not causing significant seized or spun bearings in factory-built engines and should not affect engine performance or life. A few bearing seizures have occurred in engines that have received an in-frame bearing roll-in from a dealer or engines that have received and out-of-frame rebuild from a dealer.

Solution:

Significant testing, field analysis, and review of returned bearings have been conducted to reach the following conclusions and recommendations. If no evidence of connecting rod bearing flaking has occurred within the first four oil changes, we believe that the bearing overlay surface will not flake. Factory-built engines with some connecting rod bearing LTO flaking present also continue to operate successfully and should not experience decreased reliability or durability. The appropriate use of S·O·S and oil filter inspection methods for preventive repair should be judged with caution, as is defined here. An overview of LTO flaking and recommended S·O·S monitoring practices are outlined in the 3400 Engine Major Component Performance Guide, Form Number SEBD0794, Page 41. Engine disassembly is NOT necessary, but continue to monitor the engine with S·O·S if the following conditions exist:

* Multiple S·O·S test results indicate high Lead readings [such as a lead (Pb) reading greater then 25 ppm].

* A significant number of large LTO flakes are visible in the oil filter (such as 50 or more LTO particles that are greater then 1 mm size).

* Other wear metals appear in normal amounts.

If other wear metals ALSO become elevated (especially aluminum), further investigation, possibly including disassembly and bearing inspection, will be required. In most cases, the higher Lead levels should return to normal after continued engine operation.

A Parts Stock Service Letter, PI70008, has been released to remove any suspect connecting rod bearings (9Y-7735, 9Y-9497, 9Y-6188, 4W-5739, 4P-8167, and 119-3782) with certain date codes from dealer stock. See PI70008 (December 2000 revision) for details.

The following actions are recommended to help avoid spun or seized connecting rod bearing failures in dealer rebuild engines:

* During any necessary bearing service and repair, it is especially important that the established Caterpillar guidelines for crankshaft polishing are followed. (See the 3400 Engine Major Component Performance Guide, Form Number SEBD0794, Page 33.)

* Used crankshaft journals may be buffed with a 6V-3044 Polishing Belt to remove surface rust, stains, etc. Abrasive belts should NOT be used.

* The recommended Procedure to Polish Crankshafts (Form Number SEBF8042) and Procedure to Grind Crankshafts (Form Number SEBF8094) are provided in the 3400 Engine Reuse and Salvage Guide.

* Proper cleanliness is critical during assembly.

* The use of a prelube procedure before startup is strongly recommended. (See Pressure Lubrication Procedure For Remanufactured Engine And Short Blocks, Form Number SEHS8914.)