Cummins/Onan B43 / B48 — Piston and Connecting Rod Removal
Repair & overhaul · pistons and connecting rods
For the Cummins/Onan B43 / B48, from the Cummins/Onan service manual.
Applies to: Cummins/Onan B48
Before you start
- Improper piston removal can cause piston damage. Use ridge reamer to remove cylinder ridge before removing piston.
- Improper piston cleaning can cause piston damage. Do not use a caustic cleaning solvent or wire brush for cleaning pistons.
Procedure
- Drain oil.
- Remove the cylinder head and oil base pan from the engine.
- Remove the ridge from the top of each cylinder with a ridge reamer.
- Turn the crankshaft until piston is at bottom of stroke and remove the connecting rod nuts.
- Lift the rod bearing cap from the rod and push the rod and piston assembly out through the top of the cylinder using a hammer handle.
- Mark each piston and rod assembly so they can be returned to their respective cylinders; keep rod caps with their rods.
- Remove the piston rings with a piston ring spreader.
- Remove the piston pin retainer and push the piston pin out.
- Remove dirt and deposits from piston surfaces with an approved cleaning solvent.
- Clean the piston ring grooves with a groove cleaner or the end of a piston ring filed to a sharp point.
Tools required
- ridge reamer Amazon
- hammer handle Amazon
- piston ring spreader Amazon
- groove cleaner Amazon
- compressed air Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
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.