Cummins/Onan E125 / E140 — Cylinder Head Assembly
Repair & overhaul
For the Cummins/Onan E125 / E140, from the Cummins/Onan service manual.
Applies to: Cummins/Onan E125, Cummins/Onan E140, Cummins/Onan E125H/E140H engine
Before you start
- Cylinder head can be damaged by removing it when engine is hot (above 100 F [37 C]).
- Do not over-tighten the head bolts.
Procedure
- Install a new cylinder head gasket.
- Position cylinder head and position rocker arms, bolts and washers as shown.
- Make sure pushrods are properly installed in tappets and rocker arms.
- Tighten cylinder head bolts in numbered sequence per Section 3 torques.
- Retorque bolts 2 and 4 after all bolts torqued.
- Adjust valve lash and replace valve rocker cover.
Tools required
- torque wrench Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Cylinder Head Bolts No. 1-5 M10: 42-50 N-m
- No. 6 Flange Bolt M8 x 50: 16-22 FridayParts $66.30 N-m
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.