Measuring Main Bearing Clearance - Gaging Plastic Method
WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.
- NOTE:
- The crankshaft main bearings are a precision insert type. Main bearing caps are machined with the engine block, for proper clearance, and cannot be shimmed or filed for bearing fit. If the clearances are found to be excessive, new bearings and/or engine block and cap repair or replacement may be required.
- Do not rotate the crankshaft while gaging plastic is between the crankshaft journal and the bearing surface.
- The crankshaft bearing clearances are critical. Excessive bearing clearance may affect crankshaft position sensor signals and may affect OBD II system operation.
- Remove the bearing cap side bolts prior to cap removal.
Remove the bearing caps, bearing half, and bolts. Refer to Crankshaft and Bearing Removal .
- Install gaging plastic onto the crankshaft journal. Install the gaging plastic the full width of the crankshaft bearing journal.
- Install the bearing caps, bearing half, and bolts. Refer to Crankshaft and Bearing Installation .
- Remove the bearing caps, bearing half, and bolts. Refer to Crankshaft and Bearing Removal .
Using the scale supplied with the plastic gaging kit, measure the gaging plastic at its widest area.
- If the gaging plastic shows irregularity in the journal, exceeding 0.025 mm (0.001 in), remove the crankshaft and measure the journal with a micrometer.
- If clearance cannot be brought to specifications, replace the crankshaft or engine block as required. Refer to Engine Mechanical Specifications (LC8 VIN B) , or Engine Mechanical Specifications (L96 VIN G) .