Cummins/Onan 4.0 BF-1R/9500 — Cylinder Head Removal, Cleaning and Torque
Maintenance · Cylinder heads
For the Cummins/Onan 4.0 BF-1R/9500, from the Cummins/Onan service manual.
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Before you start
- Do not remove heads when they are hot; warpage may occur.
Procedure
- Use a 1/2 inch socket wrench to remove cylinder head nuts and lift heads off.
- Clean out all carbon deposits without damaging outer sealing edges.
- Use new head gaskets and clean head and block surfaces thoroughly.
- Place heads in position and tighten nuts in sequence: 5 ft-lb, then 10 ft-lb, up to 14-16 ft-lb.
- Recheck torque before engine has run a total of 50 hours.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 14-16 Amazon eBay FridayParts $135.00 ft-lb
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.