Measuring Connecting Rod Bearing Clearances - J 43690 Method

Remove the oil pan and other necessary components to gain access to the connecting rods. Remove the oil pump, screen, and deflector, when applicable.
Rotate the crankshaft until the crankshaft journal/connecting rod to be measured is in the 10 o'clock position.
Important: The crankshaft must be secure with no movement or rotation in order to obtain an accurate reading. Remove an intermediate bearing cap, as required, in order to secure the crankshaft and allow measurement of connecting rod bearing clearances.
Remove the bearing cap bolts, cap and bearing half.

Fig 1: Bearing Caps & Bolts
Courtesy of GENERAL MOTORS CORP.

NOTE: Refer to FASTENER NOTICE in Cautions and Notices.
Insert a piece of paper card stock onto the crankshaft journal. Install the bearing half, bearing cap, and bolts. Refer to Fastener Tightening Specifications .
Install the foot (1) and bolt (2) to the pivot arm assembly (3). Tighten the bolt until snug.

Fig 2: J 43690 Foot, Bolt & Pivot Arm Assembly
Courtesy of GENERAL MOTORS CORP.
Install the screw (1 or 3) to the pivot arm assembly (2).

Fig 3: J 43690 Screw & Pivot Arm Assembly
Courtesy of GENERAL MOTORS CORP.
Install the pivot arm assembly (1) onto the connecting rod.

Fig 4: J 43690 Pivot Arm Assembly & Connecting Rod
Courtesy of GENERAL MOTORS CORP.
Position the foot of the pivot arm assembly over the large end of the connecting rod bolt.
Position the screw (1) onto the small end of the connecting rod bolt and tighten securely.

Fig 5: Positioning J 43690 Screw Onto Small End Of Connecting Rod Bolt
Courtesy of GENERAL MOTORS CORP.
Install the base (1) and bolt (2) to the oil pan rail.

Fig 6: Installing J 43690 Base & Bolt To Oil Pan Rail
Courtesy of GENERAL MOTORS CORP.
Align the center of the base (1) with the screw (3) of the pivot arm assembly. Tighten the bolt (2) until snug.

Fig 7: J 43690 Base, Screw & Bolt
Courtesy of GENERAL MOTORS CORP.
Align the link (1) of the pivot arm assembly on a plane (3) equal to that of the connecting rod beam (2).

Fig 8: Aligning J 43690 Link On Plane Equal To Connecting Rod Beam
Courtesy of GENERAL MOTORS CORP.
With the link of the pivot arm assembly aligned to the beam of the connecting rod, position the pivot arm to the base and insert the pin (1).

Fig 9: J 43690 Arm-To-Base Pin
Courtesy of GENERAL MOTORS CORP.
Insert the handle (1) to the pivot arm assembly.

Fig 10: J 43690 Handle
Courtesy of GENERAL MOTORS CORP.
Select the adapter (2), as required, and install to the swivel base (1). Tighten until snug.

Fig 11: Installing J 43690 Adapter To Swivel Base
Courtesy of GENERAL MOTORS CORP.

Important: The clamp of the swivel base and the shaft of the indicator should be free of oil or other debris. A loose or improperly clamped indicator may indicate incorrect readings.
Install the indicator (2) to the swivel base (1). Tighten the clamp of the base until snug.

Fig 12: Installing J 43690 Swivel Base To Indicator
Courtesy of GENERAL MOTORS CORP.
Install the swivel base (1) to the oil pan rail of the engine block. Tighten until snug.

Fig 13: Installing J 43690 Swivel Base To Oil Pan
Courtesy of GENERAL MOTORS CORP.
Adjust the swivel base as required and position the indicator tip slightly above the connecting rod cap. Lock the swivel base in position by rotating the locking lever (1). Do not allow the tip of the indicator to contact the connecting rod at this time.

Fig 14: J 43690 Locking Lever
Courtesy of GENERAL MOTORS CORP.
The tip of the indicator should be positioned above and NOT in contact with the cap end of the connecting rod.

Fig 15: J 43690 Indicator Tip Above Connecting Rod Cap End
Courtesy of GENERAL MOTORS CORP.
Rotate the fine adjustment knobs on the dial indicator end of the swivel base to position the tip of the indicator in contact with the connecting rod.

Fig 16: J 43690 Dial Indicator Fine Adjustment Knobs & Indicator Tip
Courtesy of GENERAL MOTORS CORP.
Lightly actuate the handle of the pivot arm assembly, multiple times in both directions, to ensure the oil film is removed from the journal.

Fig 17: Actuating J 43690 Handle
Courtesy of GENERAL MOTORS CORP.
Load the handle in the forward position and zero the dial indicator. Load the handle multiple times in both directions and record the reading.
Important: During this procedure, card stock may enter the crankshaft journal oil galleries. Be sure to remove all card stock from the bearing journal and oil galleries prior to reassembly.
Remove the bearing cap bolts, cap, and paper stock.
Replace bearing halves as required to obtain the proper bearing clearances.
Install the bearings, cap, and bolts. Refer to Fastener Tightening Specifications .

Fig 18: J 43690 Dial Indicator At Zero
Courtesy of GENERAL MOTORS CORP.