Mahindra 35 Series, Руководство по обслуживанию, Страница: 84 / 368

C-28 35 Series 4WD, Model - 3535, 4035, 4535 and 5035 SM June’08
l) If the new valve guides are replaced,
ream the valve guides to the dimensions given
in specifications.
m) If the valve seat inserts are to be replaced,
take a fine cut, if necessary, from the bottom
of the counter bore, to ensure a square seat
for the replacement insert. (See fig. 10&11)
n) Thoroughly chill the new valve seat inserts
at -60
0 C in dry ice before installation.
This prevents metal scraping from the side of
the counterbore, ensuring full contact of the
insert on the bottom and side of the
counterbore. After installation inserts peen
over the edge of the inserts around it’s entire
circumstance. The inserts should be recessed
in the Head 0.006” to 0.014”
When using carbon dioxide or dry ice,
strictly adhere to instructions to avoid injuries.
Do not touch deep frozen parts with bare
hands.
o) Reface the valve seats to the correct angle seat
that are too wide after refacing should be
narrowed by grinding the top edge of the seat
with a stone of a similar angle (15
0 angle
preferred). Refer Fig. 14
p) Mount a dial indicator on the pilot shank
and check that seat run out does not exceed
0.003”.
q) Reface the valves but reject valves that grind
down to a fine edge.
r) Using carborundum paste lap-in the valves.
Ensure that all carborundum paste is removed
from the valve and valve seats after lapping.
Excess paste must be removed with a cloth
and the head washed in the solvent and blown
dry with compressed air.
s) Check the valves in their seats using engineers
blue. A complete ring of contact must be
shown on both faces.
t) If the end of the valve stems are found to have
developed indentation (due to constant hitting
of rocker arm) the same should be removed
by fine grinding the tips and removing
sufficient metal so as to give flat & smooth
finish. However either valves or the rocker
arms which have deep indentations should not
be salvaged.
4f. ASSEMBLY :
a) Coat the valve stems with clean engine oil and
install them in their original position.
b) Install the valve spring seat and valve seals.
c) Install valve springs and retainer. Using valve
spring compressor, compress the spring and
fit the new collets.
d) After assembling the valves, ensure that the
valve depression below the cylinder head
mating face is as per the following
specifications :
DEPRESSION
MM IN
Inlet 0.89 / 0.48 0.035 / 0.019
Exhaust 1.20 / 0.78 0.047 / 0.031
e) Install the injectors and tighten the nuts to
the specified torque.
f) Check to see if nozzle protrusion will
remain specified limits after rework.
Nozzle protrusion of 1.8 to 2.3 mm
( 0.070” to 0.090” ) is to be ensured.
4g. INSTALLATION :
a) Apply a light coating of clean engine oil to
the cylinder head mating face and install new
gasket.
b) Install the guide studs as shown in Fig.15 in
the cylinder block to hold the gasket in place
and ensure the correct alignment of the
cylinder head while installation.
c) Install the cylinder head
Before installation the cylinder head check cylinder
sleeve protrusion.
If protrusion is not within specification remove
the sleeve and follow the complete procedure.
d) Install the centre rocker arm lever shaft bracket
on cylinder head and insert the long bolt.
e) Remove the guide studs then insert the
remaining bolts.
f) Tighten the bolts progressively in the order
shown in Fig.4 to the specified torque.
NOTE: Be sure there is no oil i.e. the bottom
cylinder head bolt holes to prevent
hydraulic lock when the bolts are torqued.
g) Remove the long bolt from the centre valve
rocker arm shaft bracket and remove the
bracket.
h) Install the push rods in their original position.
Manifolds, Cylinder Head & Valves