Generac — Cylinder Head and Cylinder Cover Bolts Removal and Installation
Repair & overhaul
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
- Cylinder cover bolts must be replaced after removal and are not permitted to be reused.
- Cylinder head gasket may only be used once; replace if the cylinder head is removed.
Procedure
- Rotate camshaft until the keyway is upright.
- Loosen cylinder cover bolts in the order specified in the diagram.
- Check cylinder head contact surface roughness is 0.15mm or less.
- Clean the tapped holes in the cylinder block; ensure no deposits remain.
- Rotate crankshaft until No.1 cylinder piston is about 20mm below the cylinder block deck.
- Match cylinder head gasket with dowels: 2 teeth = 478, 1 tooth = 480; position with part number side up.
- Install cylinder head with camshaft keyway perpendicularly downward.
- Install new cylinder head bolts and washers into bolt holes and screw in by hand.
- Tighten bolts in four steps: 22 ft-lbs, 37 ft-lbs, rotate 90°, rotate 90°.
Tools required
- Torque-angle 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 Step 1: 22 ft-lbs
- Step 2: 37 ft-lbs
- Step 3: 90°
- Step 4: 90°
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.