Piston, Connecting Rod, and Bearing Installation: Notes

Special Tools

• J 8037:  Ring Compressor
• J 41556:  Connecting Rod Guide
• J 43654:  Piston Pin Clip Remover and Installer
• J 43690:  Rod Bearing Clearance Checking Tool
• J 43690-100:  Rod Bearing Clearance Checking Tool-Adapter Kit
• J 45059:  Angle Meter

For equivalent regional tools, refer to Tools and Equipment .

Fig 1: Identifying Piston, Piston Rings, Piston Pin,Cylinder Bore & Bearing Surface
Courtesy of GENERAL MOTORS CORP.
1. Lightly lubricate the following components with clean engine oil:
   • The piston
   • The piston pin
   • The piston rings
   • The cylinder bore
   • The bearing surfaces
Fig 2: Locating Piston Identification Mark
Courtesy of GENERAL MOTORS CORP.
2. There are two styles of pistons in use in the LZ engine, and each piston must use the appropriate matching piston ring set. To identify which make you have, look on the bottom of the piston, in between the piston pin bores.
   • If there is an "FM" marking, it is a Federal Mogul piston and must use the Federal Mogul piston rings.
   • If there is no marking, it is a Mahle piston and must use Mahle piston rings. Failure to do so may result in engine damage.
NOTE: The tops of the first and second piston rings are marked with light green stripes to insure proper orientation on the piston. The top ring has a light green stripe 180 degrees from the gap, and the second ring has a light green stripe 90 degrees from the gap. These stripes must be facing up and in this orientation prior to installing the pistons. This is necessary for proper operation.
3. Stagger the oil control ring end gaps a minimum of 90 degrees.
4. Stagger the compression ring end gaps a minimum of 25 mm (1 in).
5. Install the J 8037:  compressor onto the piston and compress the piston rings.
Fig 3: Identifying Correct Piston Installation
Courtesy of GENERAL MOTORS CORP.
NOTE: When assembling the connecting rod to the piston, make sure the connecting rod reference mark (2) is facing towards front of engine, and is in proper correlation with the front of engine piston reference mark (1).
6. Align the piston pin bore with the connecting rod pin bore.
Fig 4: Piston Pin Retainers
Courtesy of GENERAL MOTORS CORP.
7. Slide the piston pin (4) into the piston and the connecting rod (3).
NOTE: NEW piston pin retainers must be used. Never reuse the piston pin retainers.
8. Install NEW piston pin retainers (1) using the J 43654:  installer.
9. Ensure that the piston pin retainers are fully seated in their grooves.
10. Repeat these procedures for the remaining pistons.
11. Install the J 41556:  guide into the connecting rod.
Fig 5: Installing Piston & Connecting Rod Assembly Into Cylinder
Courtesy of GENERAL MOTORS CORP.
12. Install the piston and connecting rod assembly into the proper cylinder bore.
13. Hold the piston ring compressor firmly against the engine block. Using a wooden hammer handle, lightly tap the top of the piston until all of the piston rings enter the cylinder bore.
Fig 6: View Of Bearing, Bearing Cap & Bolts
Courtesy of GENERAL MOTORS CORP.
NOTE: When installing the pistons into the cylinder bore, make sure not to contact the piston oil nozzle with the connecting rod. Failure to do so may damage the piston oil nozzle, resulting in potential engine damage.
14. Using J 41556:  guide, guide the connecting rod end onto the crankshaft journal.
CAUTION: Refer to Fastener Caution .
15. Install the bearing, bearing cap and bolts.
    • Tighten the connecting rod bearing cap bolts a first pass to 25 N.m (18 lb ft) .
    • Tighten the connecting rod bearing cap bolts a final pass to 110 degrees using the J 45059:  meter .
Fig 7: Measuring Connecting Rod Side Clearance
Courtesy of GENERAL MOTORS CORP.
16. With the pistons and connecting rods installed, use a soft faced mallet and lightly tap each connecting rod assembly parallel to the crankpin to make sure that the rods have side clearance.
17. Measure the connecting rod side clearance using a feeler gage or dial indicator. Connecting rod side clearance should be within 0.18-0.44 mm (0.007-0.017 in).