Mitsubishi S12A2 — Check and adjust valve clearance
Adjustments · Valve mechanism
For the Mitsubishi S12A2, from the Mitsubishi owner's manual.
Applies to: Mitsubishi S12A2, Mitsubishi S12A2 engine
Before you start
- Check and adjust the valve clearance when the engine is cold.
- If bridge-to-rotator clearance is less than 1.5 mm, consult your Mitsubishi dealer.
Procedure
- Confirm top dead center on compression stroke by aligning timing mark [1.6], [2.5] or [4.3] on damper with pointer.
- Remove the rocker cover and make sure inlet and exhaust valves have clearance.
- Adjust valve height: loosen lock nut of valve-bridge adjusting screw, push down bridge and turn in screw until it touches the valve stem.
- From that position turn in the screw approximately 10° more and tighten the lock nut.
- Check clearance with a feeler gauge between rocker arm and bridge cap.
- Loosen the lock nut of the rocker arm adjusting screw and turn the screw so the feeler gauge is slightly gripped.
- Tighten the lock nut of the adjusting screw.
- Check and adjust in firing order, turning the engine in 60° increments.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Inlet valve clearance 0.4 mm [0.016 in.] (cold)
- Exhaust valve clearance 0.5 mm [0.020 in.] (cold)
- Clearance between valve bridge and valve rotator more than 1.5 mm [0.059 in.]
- Firing order (injection sequence) 1-12-5-8-3-10-6-7-2-11-4-9
Full service-parts list: Mitsubishi S12A2 →
Source: Mitsubishi 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.