Cummins/Onan — Checking Bearing Clearance With Plastigauge
Testing & diagnosis · Connecting rod bearings
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Procedure
- Make certain that all parts are marked or identified so they are reinstalled in their original positions.
- Place a piece of correct size Plastigauge in bearing cap the full width of bearing insert about 1/4 inch off center.
- Rotate crank about 30 degrees from bottom dead center and reinstall bearing cap. Tighten bolts to specified torque. Do not turn crankshaft.
- Remove bearing cap. Leave flattened Plastigauge on part to which it has adhered. Compare widest point with graduations on Plastigauge envelope to determine bearing clearance.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Tighten bolts to torque specified in Assembly Torques section
Source: Cummins/Onan service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.