Generac — Rocker Arm Mechanism and Hydraulic Lifting Rod Removal and Installation
Repair & overhaul · Valve mechanism
From a Generac service manual covering: CAC478, CAC480, SQR480. Check it applies to your exact model before use.
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Before you start
- Before installing each rocker arm and tightening the nut, the appropriate hydraulic lifting rod should be at the lowest position.
Procedure
- Loosen rocker arm nuts and remove nuts.
- Remove rocker arm supports and rocker arms.
- Remove rocker arm support shims.
- Keep each rocker arm and support group in a labelled plastic bag; nuts must not be reused.
- Check rocker arm contact surface for abnormal wear; replace if necessary.
- Lubricate rocker arms and supports with engine oil.
- Install rocker arm and support, finger screw in new nut and tighten to 20 ft-lbs.
- Remove hydraulic lifting rods in order and place in oil-filled container.
- Check both hydraulic end contact faces for wear or scratches; replace if needed.
- Apply hypoid gear lubricant or engine oil to the lifting rod and install in original order.
Specs & values
- Rocker arm stud: 18-23Nm
- Rocker arm nut: 25-29Nm
- New rocker arm nut: 20 ft-lbs
- Hydraulic lifting rod standard clearance: 0.023—0.065mm
Source: Generac 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.