Mitsubishi Evolution X. Manual - part 204

PISTON AND CONNECTING ROD

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ENGINE OVERHAUL

11B-63

REMOVAL SERVICE POINTS

.

<<A>> CONNECTING ROD REMOVAL

AK703289AE

Cylinder 
number

Mark the connecting rod on the big end with the cylinder num-
ber it is being removed from.

.

<<B>> SNAP RING REMOVAL

AK702192AC

Service hole

Insert the precise screwdriver into the service hole to remove 
the snap ring.

.

<<C>> PISTON PIN REMOVAL

AK602540

70˚C
(158˚F)

AE

Engine oil

CAUTION

The clearance between the piston and the piston pin is a 
tight fit at room temperature. Therefore, be sure the heat 
the piston before pulling out the piston pin. Use care sine 
the piston is hot after heating.
1. Into each container, pour enough engine oil to completely 

cover a piston.

2. Heat the engine oil to warm the piston to approximately 

70

° C (158° F), and then remove the piston pin.

PISTON AND CONNECTING ROD

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ENGINE OVERHAUL

11B-64

INSTALLATION SERVICE POINTS

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>>A<< PISTON PIN INSTALLATION

AK702191AD

No.1

No.2

No.3

No.4

Engine front

1. When replacing a piston, check the cylinder bore size mark 

stamped on the illustrated position of the cylinder block and 
select a corresponding piston from the table below.

Cylinder bore size 
mark

Piston size mark

A

A

B

B or none

C

C

AK702190AD

Piston size mark

Front
mark

NOTE: The piston size mark is indicated on the piston top 
face.

AK600723 AE

Engine oil

70˚C
(158˚F)

CAUTION

The clearance between the piston and the piston pin is a 
tight fit at room temperature. Therefore, be sure the heat 
the piston before pulling out the piston pin. Use care sine 
the piston is hot after heating.
2. Into each container, pour enough engine oil to completely 

cover a piston.

3. Heat the engine oil to warm the piston to approximately 

70

° C (158° F), and then remove the piston pin.

4. Sufficiently apply the engine oil to the outer circumference of 

piston pin and the small end hole of connecting rod.

AK702189AC

Front mark

PISTON AND CONNECTING ROD

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ENGINE OVERHAUL

11B-65

5. Put the front mark of connecting rod and the front mark of 

piston toward the same side, and then insert the piston pin.

6. Install the circlip to the piston according to the following 

procedure:

AK703270AC

MB992236

Circlip

Open side

(1) With the open side facing upward, install the new circlip 

to the special tool MB992236.

AK703271AC

MB992236

Piston

Circlip

Groove

Set the open side of 
the circlip to the groove

(2) Align the open side of circlip with the piston groove, and 

then set the circlip together with the special tool 
MB992236. 

AK703185AC

MD998780

Push rod

Guide A 
Ø21.9 mm (0.86 in)

(3) Install the guide A (

φ21.9 mm [0.88 inch]), to the push rod 

of special tool MD998780.

AK703272AC

MB992236

MD998780

Circlip

(4) Push the opposite side of open side with the special tool 

MD998780, and install the circlip to the piston groove.

(5) Make sure the circlip is seated into the groove. 
(6) Unless seated into the groove, the circlip must be pushed 

with the special tool MD998780 again to be seated into 
the groove. 

AK702201

PISTON AND CONNECTING ROD

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ENGINE OVERHAUL

11B-66

7. Check that the piston moves smoothly.

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>>B<< OIL RING INSTALLATION

AK400536

Upper
side
rail gap

AC

Lower
side
rail gap

Spacer gap

1. Assemble the spacer of the oil ring into the piston ring 

groove. Then, assemble the upper side rail, and after this 
assemble the lower side rail.
NOTE: Install the side rail and end gap of the spacer so that 
they are at the position as shown in the illustration.
NOTE: New spacers and side rails are an identified by color 
marks as follows:

Size

Color mark

Standard

Non mark

0.25 mm (0.010 inch) 
oversize

Two blue

AK304891

CAUTION

The side rail may be broken if its end gap is widened by a 
ring expander as in other piston rings.
2. When assembling the side rail, push it by fingers, after fitting 

one end of the side rail into the piston groove, for easy 
assembly.

3. After assembling the oil ring into the piston, make sure that 

the side rail turns smoothly to either direction.

.

>>C<< PISTON RING NO. 2 / PISTON RING NO. 1 
INSTALLATION

AK304892AD

Piston ring
expander

Use a piston ring expander to assemble piston rings with their 
identification marks facing upward. Piston rings can be assem-
bled by hand without using the piston ring expander.