Cummins/Onan B43 / B48 — Connecting Rod Bearing Clearance Check with Plastigauge
Testing & diagnosis · connecting rod bearings
For the Cummins/Onan B43 / B48, from the Cummins/Onan service manual.
Applies to: Cummins/Onan B48
Procedure
- Make certain all parts are marked or identified so they are reinstalled in their original positions.
- Place a piece of correct size Plastigauge in the bearing cap the full width of the crankshaft rod surface and about 1/4 inch (6.35 mm) off center.
- Rotate the crank about 30 degrees from bottom dead center and reinstall the bearing cap; tighten bolts to specified torque; do not turn the crankshaft.
- Remove bearing cap; the flattened Plastigauge will adhere to either the bearing cap or crankshaft.
- Compare flattened Plastigauge with the graduations on the Plastigauge envelope to determine clearance.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Connecting rod bolt 14 ft-lb (19 Nm)
Full service-parts list: Cummins/Onan B48 →
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.