Isuzu 4HK1 / 6HK1 — Adjustment of valve clearance
Adjustments · Valve train
For the Isuzu 4HK1 / 6HK1, from the Isuzu service manual.
Applies to: Isuzu 4HK1, Isuzu 6HK1
Before you start
- Adjust valve clearance carefully so that the bridge may become level (hit the end of the 2 valve axes).
- If the bridge adjusting screw is poorly adjusted, the bridge may tilt, be pushed down and seize, damaging the bridge guide.
Procedure
- Loosen all bridge and rocker arm adjusting nuts and screws (4HK1: 8 nuts/8 screws, 6HK1: 12 nuts/12 screws).
- Place a 0.4 mm thickness gauge between the No.1 cylinder rocker arm end and bridge cap.
- Tighten rocker arm adjusting screw until the gauge is snug between rocker arm end and bridge cap.
- Tighten the rocker arm lock nut.
- Tighten the bridge adjusting screw until the bridge contacts the valve head.
- Tighten the bridge lock nut.
- Check the thickness gauge is still held snugly; if too tight loosen bridge screw and nut.
- Remove the thickness gauge and repeat for remaining cylinders.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Valve clearance 0.4 mm (0.016)
- Valve bridge clearance ±0.1 mm (0.0039 in) or less
- Tightening torque: 22 N·m (16 lb ft)
Full service-parts list: Isuzu 4HK1 →, Isuzu 6HK1 →
Source: Isuzu 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.