Cummins/Onan — Check Connecting Rod Bearing Clearance with Plastigauge
Testing & diagnosis · Connecting rod bearings
From a Cummins/Onan service manual covering: P216, P218, P220, P248. Check it applies to your exact model before use.
Applies to: Cummins/Onan P216, Cummins/Onan P218, Cummins/Onan P220, Cummins/Onan P248
Procedure
- Make certain all parts are marked or identified so they are installed in their original positions.
- Using a clean, dry cloth, thoroughly clean all oil from the crankshaft journal and the connecting rod.
- Place a piece of correct size Plastigauge in the bearing cap the full width of the journal surface and about 1/4 inch (6.35 mm) off center.
- Rotate the crankshaft about 30 degrees from bottom dead center and reinstall the bearing cap.
- Tighten the rod bolts to the torque specified in Section 4 Assembly; do not turn the crankshaft.
- Remove the bearing cap; the flattened Plastigauge will adhere to either the bearing cap or the crankshaft.
- Compare the flattened Plastigauge with the graduations on the Plastigauge envelope to determine the clearance.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Connecting rod bolts 12-14 Amazon eBay FridayParts $33.00 lb-ft (16-19 FridayParts $28.30 Nm)
- Large bore clearance 0.0020 - 0.0033 in (0.051 - 0.084 mm)
Full service-parts list: Cummins/Onan P216 →, Cummins/Onan P218 →, Cummins/Onan P220 →, Cummins/Onan P248 →
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.