GM Service Manual Online
For 1990-2009 cars only

Special Tools

    • EN 46121 Connecting Rod Guide Pin Set
    •  EN 48589 Crankshaft Rotation Socket
    • EN 8037 Ring Compressor
    • EN 43690 Rod Bearing Clearance Checking Tool
    • EN 43690-100 Rod Bearing Clearance Checking Tool - Adapter Kit
    •  EN 45059 Torque Angle Sensor Kit

For equivalent regional tools, refer to Special Tools.

Piston and Connecting Rod Assembly Procedure


    Object Number: 1313400  Size: SH
  1. Liberally lubricate the cylinder walls, piston rings and piston skirts with engine oil.
  2. Note: 

       • The piston is directional and must be installed in the engine block in the proper direction.
       • The dot on the top of the piston must face the front of the engine.

  3. Select the correctly numbered piston/connecting rod assembly for the cylinder. A dot (1) showing proper piston orientation is located on the top of the piston.

  4. Object Number: 1313403  Size: SH

    Note: If the connecting rod bearings have been used in a running engine, you must replace them with NEW connecting rod bearings for reassembly.

  5. Install the connecting rod bearing into the connecting rod.
  6. Install the EN 46121 connecting rod guide pin set into the connecting rod bolt holes.
  7. Compress the piston rings using the EN 8037 ring compressor or equivalent.

  8. Object Number: 1313406  Size: SH

    Note: Extreme care must be used when installing the piston and connecting rod in order to be sure the rod does not scrape or nick the cylinder bore, the oil jets, or the crankshaft surfaces.

  9. Using both hands, slowly guide the piston and connecting rod assembly into the cylinder from the top and bottom of the cylinder. DO NOT allow the connecting rod to contact the cylinder wall.
  10. When the EN 8037 ring compressor contacts the deck surface, gently tap the piston into the cylinder using the handle end of a dead-blow hammer. Guide the connecting rod onto the crankshaft bearing journal using the EN 46121 connecting rod guide pin set while gently tapping the piston into the cylinder with a soft-blow hammer.

  11. Object Number: 1866871  Size: SH
  12. Remove the EN 46121 guide pin from the connecting rod bolt holes.

Connecting Rod Bearing Clearance Measurement Procedure - Using Plastic Gaging

    Note: Connecting rod bearings that have been run in an engine should NEVER be reused.

    Before final assembly it is important to check the clearance of the new connecting rod bearings.

  1. Place a length of fresh, room temperature plastic gaging material all the way across the connecting rod bearing journal.
  2. Install the connecting rod bearing into the connecting rod cap.
  3. Note: The connecting rod is non-directional therefore the connecting rod bearing lock tangs can face inboard or outboard.

  4. Install the connecting rod end cap on its original connecting rod and ensure the bearing lock tangs are aligned on the same side of the rod.
  5. Caution: Refer to Fastener Caution in the Preface section.


    Object Number: 1866870  Size: SH

    Notice: Do not lubricate the NEW connecting rod bolts. The NEW bolts have a pre-applied graphite lubricant. Applying lubricant to the connecting rod bolts will effect the clamp load when the connecting rod bolts are torqued. Improper clamp load can lead to component failure and extensive engine damage.

    Note: Reuse the old connecting rod bolts ONLY for measuring the connecting rod bearing clearance.

  6. Install the connecting rod bolts into the connecting rod cap and tighten to  30 N·m (22 lb ft).
  7. Loosen the connecting rod bolts until the torque reading is zero.
  8. Re-tighten the connecting rod bolts in two passes:
  9. 6.1. Tighten the connecting rod bolts in the first pass to  25 N·m (18 lb ft)
    6.2. Tighten the connecting rod bolts a second pass to  110 degrees using the EN 49411 angle sensor .
  10. Allow the assembly to sit for at least 2 minutes.
  11. Remove the connecting rod cap bolts.
  12. Remove the connecting rod cap.

  13. Object Number: 54236  Size: SH
  14. Determine the connecting rod bearing clearance by comparing the width of the flattened plastic gaging material at its widest point with the graduation on the gaging material container.
  15. Compare your measurements with the engine mechanical specifications. If the new bearings do not provide the proper crankshaft to connecting rod bearing clearance, inspect the following:
  16. 11.1. Re-measure the crankshaft connecting rod journals for the correct specified size and ensure the proper new bearings are being installed. If the crankshaft connecting rod journals are incorrectly sized, replace or regrind the crankshaft. Crankshaft machining is permitted and undersized bearings are available. Refer to Engine Mechanical Specifications.
    11.2. Re-measure the connecting rod bearing bore diameter to ensure proper size. The connecting rod is not machinable and the connecting rod must be replaced if out of specification. Refer to Engine Mechanical Specifications.
  17. Clean the plastic gaging material from the connecting rod bearing journals using a soft lint-free cloth.

Connecting Rod Bearing Clearance Measurement Procedure - Using EN 43690 and EN 43690

The EN 43690 rod bearing clearance checking tool and the EN 43690 rod bearing clearance checking tool - adapter kit have been developed as a more accurate method to measure connecting rod bearing clearances. The instructions below provide an overview of tool set-up and usage. For more detailed information, refer to the tool instruction sheets as supplied by the tool manufacturer.


Object Number: 627091  Size: SH

EN 43690 rod bearing clearance checking tool .

    • EN 43690-20 Swivel Base  (1)
    • EN 43690-19 Dial Indicator  (2)
    • EN 43690-2 Base  (3)
    • EN 43690-5, -6 Handle  (4)
    • EN 43690-10, -11 Foot  (5)
    • 280307 Screw  (6)
    • EN 43690-1 Pivot Arm Assembly  (7)
    • EN 43690-3, -7, -8 Screws  (8)
    • 280319 Screw  (9)
    • 280311 Screw  (10)
    • EN 43690-17, -18 Adapter  (11)
    • 280310 Pin  (12)

Object Number: 836375  Size: SH

EN 43690-100 rod bearing clearance checking tool - adapter kit

    • EN 43690-104 Spacer  (1)
    • EN 43690-105 Retainer Plate  (2)
    • 505478 Bolt  (3)
    • 511341 Bolt  (4)
    • EN 43690-106 Retainer Plate  (5)
    • EN 43690-107 Cap  (6)
    • EN 43690-102 Foot  (7)
    • EN 43690-101 Pivot Arm Assembly  (8)
    • EN 43690-103 Adapter  (9)
    • 505439 Adapter  (10)

    Object Number: 1866870  Size: SH

    Note: Connecting rod bearings that have been run in an engine should NEVER be reused.

    Before final assembly it is important to check the clearance of the new connecting rod bearings.

  1. Install the connecting rod bearing into the connecting rod cap.
  2. Note: The connecting rod is non-directional therefore the connecting rod bearing lock tangs can face inboard or outboard.

  3. Install the connecting rod end cap on its original connecting rod and ensure the bearing lock tangs are aligned on the same side of the rod.
  4. Notice: Do not lubricate the NEW connecting rod bolts. The NEW bolts have a pre-applied graphite lubricant. Applying lubricant to the connecting rod bolts will effect the clamp load when the connecting rod bolts are torqued. Improper clamp load can lead to component failure and extensive engine damage.

    Note: Reuse the old connecting rod bolts ONLY for measuring the connecting rod bearing clearance.

  5. Install the connecting rod bolts into the connecting rod cap and tighten to  30 N·m (22 lb ft).
  6. Loosen the connecting rod bolts until the torque reading is zero.
  7. Re-tighten the connecting rod bolts in two passes:
  8. 5.1. Tighten the connecting rod bolts in the first pass to  25 N·m (18 lb ft)
    5.2. Tighten the connecting rod bolts a second pass to  110 degrees using the J 45059 angle meter .
  9. Rotate the crankshaft until the crankshaft journal and the connecting rod to be measured is in the 12 o'clock position.
  10. Note: The crankshaft must be secure with no movement or rotation in order to obtain an accurate reading.

  11. Remove the crankshaft main bolts required to install the EN 43690-105 retainer plate .
  12. Note: Do not allow the EN 43690-105 retainer plate screw to contact the reluctor ring.

  13. Install the EN 43690-105 retainer plate and crankshaft main bolts.
  14. Loosen the connecting rod bolts until the torque reading is zero.
  15. Re-tighten the connecting rod bolts in two passes:
  16. 10.1. Tighten the connecting rod bolts in the first pass to  25 N·m (18 lb ft)
    10.2. Tighten the connecting rod bolts a second pass to  110 degrees using the EN 45059 angle meter .
  17. During and after installation, ensure each piston is positioned properly in the correct cylinder. The locating arrow on the top of each piston must be pointing toward the front of the engine.
  18. Repeat these procedures for the remaining piston/connecting rod assemblies using the sing the EN 45059 angle meter in order to rotate the crankshaft.

Connecting Rod Final Assembly Procedure

  1. Guide the connecting rod away from the crankshaft connecting rod journal in order to lubricate the crankshaft connecting rod bearing journal.
  2. Apply a liberal amount of crankshaft prelube or clean engine oil to the crankshaft connecting rod bearing journal. Refer to Adhesives, Fluids, Lubricants, and Sealers for the recommended oil.
  3. Guide the connecting rod to the crankshaft connecting rod journal.
  4. Install the connecting rod end cap on its original connecting rod and ensure the bearing lock tangs are aligned on the same side of the rod.

  5. Object Number: 1871086  Size: SH

    Notice: Do not lubricate the NEW connecting rod bolts. The NEW bolts have a pre-applied graphite lubricant. Applying lubricant to the connecting rod bolts will effect the clamp load when the connecting rod bolts are torqued. Improper clamp load can lead to component failure and extensive engine damage.

    Note: DO NOT reuse the old connecting rod bolts.

  6. Install the NEW connecting rod bolts into the connecting rod cap and tighten to  30 N·m (22 lb ft).
  7. Loosen the connecting rod bolts until the torque reading is zero.
  8. Re-tighten the connecting rod bolts in two passes:
  9. 7.1. Tighten the connecting rod bolts in the first pass to  25 N·m (18 lb ft)
    7.2. Tighten the connecting rod bolts a second pass to  110 degrees using the EN 45059 angle meter .
  10. During and after installation, ensure each piston is positioned properly in the correct cylinder. The locating arrow on the top of each piston must be pointing toward the front of the engine.
  11. Repeat these procedures for the remaining piston/connecting rod assemblies using the EN 48589 socket in order to rotate the crankshaft.