Cummins/Onan — Cylinder Head Removal and Cleaning
Repair & overhaul · Cylinder heads
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan NHC-NHCV, Cummins/Onan NHC-NHCV engine
Before you start
- Do not remove heads when hot. Warpage may occur.
Procedure
- Use 1/2 inch socket wrench to remove cylinder head bolts; lift heads off.
- Clean out carbon deposits without damaging sealing edges.
- Use new head gaskets and clean head and block surfaces.
- Place heads in position and torque bolts in sequence: 5 ft-lb, then 10 ft-lb, etc., to 17-19 ft-lb.
- Recheck torque after engine has run 50 hours.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Head bolt torque 17-19 FridayParts $20.66 ft-lb
Full service-parts list: Cummins/Onan NHC-NHCV →
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.