Cummins/Onan — Cylinder Headbolt Tightening
Repair & overhaul
From a Cummins/Onan owner's manual — check it applies to your exact model before use.
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Procedure
- Coat the cylinder head bolts with head gasket sealer.
- Tighten the head bolts in the sequence shown in three progressive steps.
- Step 1 (cold): 55 foot-pounds.
- Step 2 (cold): 65 foot-pounds.
- Final (hot): 75 foot-pounds after minimum 30 minutes at idle speed.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 55 / 65 / 75 foot-pounds progressive steps
Source: Cummins/Onan owner's 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.