Service manual

181 CID (3.0L) 4 CYLINDER GM ENGINE

SERVICE MANUAL NUMBER 26

90-861329--1 MARCH 1999 Page 3A-51

PISTON PINS

1. Piston pin clearance is designed to maintain adequate clearance under all engine

operating conditions. Because of this, piston and piston pin are a matched set and not

serviced separately.

2. Inspect piston pin bores and piston pins for wear. Piston pin bores and piston pins must

be free of varnish and scuffing when measured. Measure piston pin with a micrometer

and piston pin bore with a dial bore gauge or inside micrometer. If clearance is in excess

of the .001 in. (0.02 mm) wear limit, replace piston and piston pin assembly.

Reassembly

PISTONS AND PISTON PINS

IMPORTANT: When reassembling pistons and connecting rods, the following must

be kept in mind.

• Piston and pin are machine fitted to each other and must remain together as a

matched set. Do not intermix pistons and pins.

• If original pistons and/or connecting rods are being used, be sure to assemble

pistons and connecting rods so they can be reinstalled in same cylinder from

which they were removed.

• Connecting rod bearing tangs are always toward outside of cylinder block.

72368

a-Rod Bearing Tangs

• Notch on piston must be positioned toward the front of the engine.

72896

a-Notch

Index