Mitsubishi S12A2 User Manual

6-3
Chapter 6 INSPECTION AND REPAIR OF BASIC ENGINE
Chapter 6 INSPECTI ON AND REPA IR OF BASIC ENGINE
1. Cylinder Head and Valve Mechanism - Inspect and Repair
1.1 Bushing Inside Diameter and Shaft Outside Diameter of Rocker - Measure
Measure the inside diameter of the rocker bushing and the
outside diameter of the rocker shaft.If the measurement
exceeds the limit, replace the rocker bushing or rocker shaft
with a new one.
Bushing Inside Diameter and Shaft Outside Diameter
of Rocker - Measure
1.2 Rocker Bushing - Replace
(1) Pull out the rocker bushing using the rocker bushing
puller.
Rocker Bushing - Remove
(2) Install a new rocker bushing using the rocker bushing
puller.
Face the cut of the rocker bushing upward, and align
the position indicated in the right figure. Press fit the
rocker bushing from the chamfered side of the rocker
bushing hole.
(3) Make sure the rocker arm is at a specified positional
relationship with respect to the rocker bushing.
(4) Measure the inside diameter of rocker bushing that has
bee installed.
If the value is smaller than the standard, ream the inside
diameter to the standard.
Rocker Bushing - Insert
Rocker Bushing - Position
Item
Nominal
value
Standard value Limit value
Rocker bushing inside
diameter
ø32 mm
[1.26 in.]
32.055 to
32.080 mm
[1.26 to 1.26 in.]
32.100 mm
[1.50 in.]
Rocker shaft outside
diameter
ø32 mm
[1.26 in.]
31.975 to
31.991 mm
[1.2588 to
1.2594 in.]
31.950 mm
[1.2578 in.]
Measuring
direction
Measuring
direction
Measuring
position
If rocker bushing notch is not aligned with center axis
of screw hole, oil will not feed from rocker arm to valve,
resulting in wear of rocker arm and bridge, or seizure
of valve.
Rocker bushing puller
P/N:32591-02600
Removal
Rocker arm
Rocker bushing
Rocker bushing puller
P/N:32591-02600
Press-fit
Press-fit it from
chamfered side
Turn up
the notch.
Rocker arm
Rocker bushing
ٖٖٖ
3.2S
Ra0.8μm{ }
Bushing inside surface
roughness
q
q
38°
Oil hole
Inner peripheral groove
Rocker bushing
notch
Rocker bushing
joint
Press-fit so that the rocker bushing notch is aligned
parallel to the center axis of screw hole.
Rocker bushing
Rocker arm

Mitsubishi S12A2 Specifications

General

Brand	Mitsubishi
Model	S12A2
Category	Engine
Language	English