1991 MITSUBISHI 3000GT Service Manual

ENGINE - Rocker Arm and Camshaft11-31
ROCKER ARM AND CAMSHAFTREMOVAL AND INSTALLATION
11 Nm8 ftlbs.
MllZA-0
7EN0244
Removal steps
I. Crank angle sensor adaptor2. Bearing cap front3.Oil seal
4. Bearing cap rear
5.Circular packing6.Bearing cap No.27.Bearing cap No.4
8.Bearing cap No.3
9.Camshaft10.Rocker arm11.Lash adjuster
Installation steps
11. Lash adjuster10. Rocker arml * 9. Camshaft*a 8. Bearing cap No. 3l *7. Bearing cap No. 4l *6. Bearing cap No. 2** 4. Bearing cap rearI)* 2. Bearing cap front*+ 5. Circular packingl 43. Oil sealI. Crank angle sensor adaptor
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11-32ENGINE - Rocker Arm and Camshaft
r
I
/7EN024E
Small wire
8ENOO58
Identification mark(stamped on hexagon section)
7EN0249
Front sideINSPECTION
MllZCAB
CAMSHAFTMeasure cam height (longer diameter of the cam). If it exceeds
the limit, replace the camshaft.
Standard value:
Intake side
35.49 mm (1.3972 in.)
Exhaust side
35.20 mm (1.3858 in.)
Limit:
Intake side
34.99 mm (1.3776 in.)
Exhaust side
34.70 mm (1.3661 in.)SERVICE POINTS OF INSTALLATION
MllZDAK
11. INSTALLATION OF LASH ADJUSTER
(1) Immerse the lash adjuster in clean diesel fuel.
(2) Using a small wire, move the plunger up and down 4 or
5 times while pushing down lightly in the check ball in
order to bleed out the air.
(3) Install the lash adjuster to the cylinder head.
9. INSTALLATION OF CAMSHAFT
(1) Turn the crankshaft to bring No.1 cylinder to the top
dead center.
(2) Check that the rocker arm is installed correctly on the
lash adjuster and valve.
(3) Install the camshaft noting the identification mark
(stamped on the hexagon sectioned).
Identification mark: Intake sideV
Exhaust side C
(4) Install the camshafts with their dowel pins positioned
as shown in the illustration.
Rear side ,
Approx. 100”
Pl
Frontm&k
M
0
/
Cap No
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Identificationmark
7EN03168. 7. 6. 4. 2. INSTALLATION OF BEARING CAPS
(1) Install noting the identification mark and cap No. No.2, 3
and 4 bearing caps bear the front mark. Install these
caps with the mark lined up with the front mark on the
cylinder head.
Identification mark: Intake side
IExhaust side E

ENGINE - Rocker Arm and Camshaft11-33
About 10 mm C.39 In.17ENO248
i,(2) Tighten gradually in two or three steps and finally
tighten to specified torque.
(3) Measure the camshaft end play. Replace if the limit is
exceeded.
Standard value: 0.1
- 0.2 mm (.004 - .008 in.)
Limit: 0.4 mm
(.016 in.)
NOTEIf the bearing cap is installed with the cylinder cap
removed, the valve will protrude. Install, therefore, with
the cylinder head lifted by about
10 mm (.39 in.).
5. INSTALLATION OF CIRCULAR PACKING
Using the special tool, insert the circular packing.
3. INSTALLATION OF OIL SEAL
Using the special tool, insert the oil seal.
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II-34ENGINE - Cylinder Head and Valve
CYLINDER HEAD AND VALVEREMOVAL AND INSTALLATION
’ 104e------1510
11-A16-----P
Removal steps
l * l +I. Cylinder head bolt
2. Washer
3. Cylinder head assembly
l +4. Cylinder head gasket
** l *5. Retainer lock
6. Valve spring retainer
l *7. Valve spring
8. Intake valve
l * l *9. Retainer lock10. Valve spring retainer
125 Nm90 ftlbs.
7E NO254
l * 11. Valve spring12.Exhaust valvel 413.Valve stem seal
14. Valve spring sheet
I)* 15. Valve stem seal
16. Valve spring sheet
17. Intake valve guide
18. Exhaust valve guide
19. Intake valve sheet
20. Exhaust valve sheet
3
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ENGINE - Cvlinder Head and ValveII-35SERVICE POINTS OF REMOVAL
1. REMOVAL OF CYLINDER HEAD BOLT
Using the special tool, remove the cylinder head
u 1 \+-MD998735 15. 9. REMOVAL OF RETAINER LOCK
Using the special tool, remove the retainer lock.
’ 6EN02INSPECTION
CYLINDER HEAD
MllOBACbolts.
MllOCAO
(1) Using a straight edge and feeler gauge, measure the
flatness of the cylinder head gasket surface.
Standard value: 0.03 mm (0012 in.) or less
Limit: 0.2 mm
(008 in.)
(2) If the measured flatness exceeds the limit, grind and repair
the surface to gain the flatness of standard value or less.
Grinding Limit: 0.2 mm
(.008 in.)
Caution
When the cylinder block is assembled, 0.2 mm
(.008 in.)or less of grinding is permissible.
VALVESReplace the valve if the margin (thickness of the valve head)
exceeds the limit.
Standard value:
Intake side1.0 mm (039 in.)
Exhaust side1.5 mm (.059 in.)
Limit:
Intake side0.5 mm (019 in.)
Exhaust side1 .O mm (.039 in.)
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11-36ENGINE - Cylinder Head and Valve
SquarenssVALVE SPRINGS
(1) Check free length of each valve spring and replace if
necessary.
!
FreelengthStandard value: 46.9 mm
(1.846 in.)\bJLimit: 45.9 mm
(1.807 in.)
(2) Using a square, test squareness of each valve spring. If
spring is excessively out of square, replace it.
Standard value: Less than 2”
Limit: 4
1 EN035
VALVE GUIDES
1 EN29ECheck the valve stem-to-guide clearance. If the clearance
exceeds the service limit, replace the valve guide with new
oversize part.
Standard value:
Intake
Exhaust0.02 - 0.05 mm (0008 - .0020 in.)
Limit:0.05
- 0.09 mm (.0020 - .0035 in.)
Intake
Exhaust0.10 mm (0039 in.)
0.12 mm (0047
in.)6EN043
1AVALVE SEAT RECONDITIONING PROCEDURES
(I 1 Before valve seat reconditioning, check valve stem to guide
clearance.
(2)Recondition the valve seat with a seat grinder or cutter. The
valve seat width should be the specified value at the center
of the valve face.
Inspect the valve seat with prussian blue to determine
LJwhere the valve contacts the seat. To do this, coat valve
seat lightly with prussian blue, and then set valve in place.
Rotate the valve with light pressure. If the blue is
transferred to the center of valve face, contact is satisfac-
tory.
If the blue is transferred to top edge of the valve face, lower
valve seat with a 30 degrees stone or cutter. If the blue is
transferred to the bottom edge of valve face, raise valve
seat with a 65 degrees stone or cutter.
Valve seat diameter:
Intake34 mm (I .34 in.)
ExhaustSeat width: 0.9
29.5 mm (1.16 in.)
- 1.3 mm (035 - .051 in.)
(3) The valve and valve seat should be lapped with a lapping
compound.
VALVE SEAT REPLACEMENT PROCEDURE
(1) Grind the valve seat to be replaced from the inside to thin
the wall thickness. Then, remove the valve seat.
1 ENOE18
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ENGINE - Cylinder Head and Valve
Oversize I.D.
Valve(2) Rebore the valve seat hole in
oversize valve seat diameter.Seat Insert Oversizescylinderhead to a selected
DescriptionSize mm (in.)1 Size mark /Seat insEt(,ke;ght H/Cylinder head I.D.
mm (in.)
Intake valve0.3i.012)0,s.
I
30
I
7.5-7.7(.295-,303)36.300-36.325(1.4291-1.4301)
seat insert
0.6(.024)O.S.607.8-8.0(.307-,315)36.600-36.625(1.4409-1.4419)
Exhaust valve
seat insert
0.3l.012)0,s.7.9-8.1(.311-.319)33.300-33.325(1.3110-1.3120)
0.6(.024)O.S.8.2-8.4t.323-,331)33.600-33.625(1.3228-1.3238)
7EN02E(3) When press-fitting the valve seat, chill the valve seat with
liquid nitrogen so that the cylinder head bore is not
damaged by galling.
(4)Using the valve seat grinder or cutter, correct the valve seat
to the specified width and angle.
(5) See “VALVE SEAT RECONDITIONING PROCEDURES.”
VALVE GUIDE REPLACEMENT PROCEDURE
MllPJDB
(1) Using suitable rod and a press, press the valve guide out of
the cylinder head toward the cylinder block side.
(2) Rebore the valve guide hole to the oversize valve guide
outside diameter
to be press-fitted.
CautionDo not use a valve guide of the same size as the one
removed.12.250-12.268
(.4823-.4830)12.500-12.518
(.4921-.4928)(3) Install the valve guide until a protrusion of 17.5 mm
(.689in.) is obtained. See the illustration.
NOTE1. Press-fit the valve guide from the cylinder head top
surface.
2. Note the difference in lengths of the valve guides for
the intake and exhaust: intake 45.5 mm (1.791 in.) and
exhaust 50.5 mm (1.988 in.).
3. After the valve guide has been installed in position,
insert a new valve to ensure that it slides smoothly.
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11-38ENGINE - Cylinder Head and Valve
Enamelcoatedside
Springretainer
Stem seal
pring sheet
6EN024SERVICE POINTS OF INSTALLATION
MllODAH15.13. INSTALLATION OF VALVE STEM SEAL
Install the spring seat, then using the special tool, install the
stem seal by lightly tapping the tool.
d
Caution1. Incorrect installation of the seal without using the
special tool will result in poor sealing and cause oilleakage down valve guide.
2. Do not reuse stem seal.
11.7. INSTALLATION OF VALVE SPRING
Valve springs should be installed with the enamel coated
side toward the valve spring retainer.
9. 5. INSTALLATION OF RETAINER LOCK
Using the special tool, install the retainer lock
4. INSTALLATION OF CYLINDER. HEAD GASKET
Identification mark:

2DN
2DT
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