Connecting Rod Bearing Inspection

Fig 1: Placement Of Plastigage On Journal

Courtesy of GENERAL MOTORS CORP.

CAUTION: Refer to Battery Disconnect Caution in Cautions and Notices.

Coat the connecting rod bearings with engine oil.

IMPORTANT: Grease the connecting rod journals and lubricate the connecting rod bearings slightly so that the plastic gaging thread does not tear when the connecting rod bearing caps are removed.

Install the upper connecting rod bearings into the connecting rod journals.
Install the lower connecting rod bearings into the connecting rod bearing caps.
Measure all of the connecting rod bearing clearances using a commercially available plastic gaging, ductile plastic threads.

Fig 2: Using J 45059 Or KM-470-B To Torque Rod Bolts

Courtesy of GENERAL MOTORS CORP.

Cut the plastic gaging threads to the length of the bearing width. Lay them axially between the connecting rod journals and the connecting rod bearings.
Install the connecting rod bearing caps.

NOTE: Refer to Fastener Notice in Cautions and Notices.

Install the connecting rod bearing cap bolts.
Tighten: Tighten the connecting rod bearing cap bolts to 25 N.m (18 lb ft).
Using the J 45059 or the KM-470-B (1), tighten the crankshaft cap bolts another 30 degrees plus 15 degrees.

Fig 3: Measuring Plastigage

Courtesy of GENERAL MOTORS CORP.

Remove the connecting rod bearing caps.
Measure the width of the flattened plastic thread of the plastic gaging (1) using the scale printed on the plastic gaging package. Plastic gaging is available for different tolerance ranges.
Inspect the bearing clearance for permissible tolerance ranges. Refer to Engine Mechanical Specifications .