Connecting Rod Measurement Procedure

Piston Pin End

Fig 1: Measuring Piston Pin Diameter
Courtesy of GENERAL MOTORS COMPANY
NOTE:

Measurements of all components should be taken with the components at normal room temperature.

1. Using an outside micrometer, take 2 measurements of the piston pin in the area of the connecting rod contact.
Fig 2: Checking Connecting Rod Piston Pin Bore Dimensions
Courtesy of GENERAL MOTORS COMPANY
2. Using an inside micrometer, measure the connecting rod piston pin bore.
3. Subtract the piston pin diameter from the piston pin bore.
4. Compare the clearance measurements to the proper specifications. Refer to Engine Mechanical Specifications .
5. If the clearance is excessive, replace the piston pin. If a new pin does not resolve the clearance problem, replace the connecting rod.

Connecting Rod Crankshaft Bearing End

Fig 3: Measuring Connecting Rod Crankshaft Bearing Bore
Courtesy of GENERAL MOTORS COMPANY
NOTE:

Measurements of all components should be taken with the components at normal room temperature.

NOTE:

The bore specifications are based on connecting rod bolts at full torque specification.

1. Using the old bolts, tighten the connecting rod cap bolts to 25 N.m (18 lb ft) plus 75 degrees.
2. Using an inside micrometer, measure the connecting rod crankshaft bearing bore.
3. Compare the bore measurements to the proper specifications. Refer to Engine Mechanical Specifications .
4. Replace the connecting rod if the bore is out of specifications. DO NOT recondition the connecting rod.