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ENGINE
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5. Fit Valve guide oil seals
D. Valve Seat :
1. Check valve seat height with respect to
cylinder head mating surface. Replace valve
seat inserts if they are worn out beyond
specified limit.
2. Cut exhaust and inlet valve seats with a
general 45 deg. cutter.
NOTE
Valve seat must be absolutely faultless and
without any chatter marks.
3. If necessary lap the valve seats to a smooth
and even finish by using suitable hand pump
grinder or a lapping paste and valve itself.
4. Smear valve seat with carbon blue. Install
valve in guide and turn it slowly under axial
pressure.
5. Contact line on valve seat must be around
entire circumference at equal width.
6. Distance between narrow diameters of valve
face to contact line should be minimum 0.5
mm.
7. Check for leakages through valve seat by
pouring gasoline on valve head. Gasoline must
not seep past valve seat.
E. Valve Seat Insert :
1. For removing valve seat inserts from cylinder
head use suitable boring machine. Bore old
insert thin (About 0.5 mm thickness) and then
pry it out.
2. Alternatively use a suitable turning tool to cut
an annular groove into valve seat insert and
then pull it out with a suitable puller. In order to
avoid damaging machined cylinder head
mating surface with crank case, place any soft
protective sheet metal under supports of puller.
3. Measure valve seat insert bore diameter in
cylinder head.
4. If boring and prying is done carefully without
damaging valve seat insert bore in cylinder
head, fitment of an oversize valve seat insert
will not be necessary.
5. Re-machined valve seat insert bore in cylinder
head must be exactly at right angle to cylinder
head mating surface with crank case.
6. All specified dimensions should be strictly
maintained to ensure proper interference of
valve seat insert in its bore.
7. Clean valve seat insert and its bore in cylinder
head thoroughly.
F. Just Before Installation :
1. Place valve seat insert in mixture of Methanol
and dry ice for about 20-30 minutes to bring
temperature down to -150ºC.
2. Heat cylinder head to approximately 80ºC in
hot water bath.
3. Install valve seat insert in cylinder head bore
quickly by light hammering.
4. Machine valve seat in cylinder head.
G. Cam Shaft :
1. Check cam shaft run out at 2nd journal by
supporting it on V-block at 1st and 3rd journal.
2. Check cam shaft journal dimensions. Record
the readings.
3. Carry out visual inspection of cam shaft for:
• Overheating of journals, this is indicated by
bluish/ brown colour.
• Deep scoring marks on journals and cam
lobes
• Cracks, which should be checked on a
magnetic crack detector.
4. Check hardness of cam shaft journals and
cam lobes, it should be 47 HRC.
H. Hydraulic Lash Adjuster :
Hydraulic Lash Adjuster supports the pivot end of
the rocker arm while automatically controlling the
rocker arm position to keep it in contact with the
camshafts and valve.
The range of the hydraulic lash adjuster
accommodates engine build tolerances; hence no
adjustment is required during engine assembly. It
also compensates for variation that occurs during
the life of the engine.
For information on HLA and inspection refer
Lubrication section.