seats NISSAN PATROL 1998 Y61 / 5.G Engine Mechanical Workshop Manual

VALVE OIL SEAL
1. Remove timing belts.
2. Remove camshaft sprocket and back covers.
3. Remove camshaft brackets by loosening bracket nuts from
center to outside in two or three stages.
4. Remove camshaft oil seals and camshaft.
5. Remove valve lifters and mark order No. on each lifter.
6. Replace valve oil seal according to the following procedure.
When replacing valve oil seal, set the corresponding piston at
TDC. Failure to do so causes the valve to drop into the cylin-
der.
1) Set No. 1 cylinder at TDC.
2) Remove valve springs and valve oil seals for No. 1 and No. 6
cylinders. Valve spring seats should not be removed.
3) Install new valve oil seals for No. 1 and No. 6 cylinders as
illustrated. Reinstall valve springs. (narrow pitch side toward
cylinder head)
4) Install valve spring retainers on intake valves and valve rotators
on exhaust valves, and remount valve assembly.
5) Set No. 2 cylinder at TDC.
6) Replace valve oil seals for No. 2 and No. 5 cylinders according
to steps 2) and 3).
7) Set No. 3 cylinder at TDC.
8) Replace valve oil seals for No. 3 and No. 4 cylinders according
to steps 2) and 3).
9) Install valve lifters in original positions.
SEM716B
SEM790F
SEM745B
SEM746B
OIL SEAL REPLACEMENT
EM-21

3. Drive in the new guide until it projects out 10.3 mm (0.406 in).
4. Ream the bore using suitable tool.
Reaming bore:
7.000 - 7.018 mm (0.2756 - 0.2763 in)
COMBUSTION CHAMBER REPLACEMENT
Usually combustion chamber should not be removed.
However, if there are cracks or extensive damage, it should be
replaced.
1. Remove glow plug connecting plate, glow plugs and injection
nozzle.
2. Remove combustion chamber so that cylinder head will not be
damaged.
Be careful not to scratch inside of nozzle hole.
3. Install combustion chamber.
(1) Heat cylinder head 150 to 160ÉC (302 to 320ÉF) in oil.
(2) Align combustion chamber knock pin with cylinder head notch,
and install it into cylinder head using a plastic-tip hammer.
VALVE SEATS
1. Check valve and valve seat for contact.
Coat the valve face with prussian red lead. If contact is wrong,
correct valve seat. If the valve red lead appears 360É around
face, the valve stem and face are concentric. If not, repair or
replace valve.
2. Check valve seats for any evidence of pitting on valve contact
surface, and reseat or replace if worn out excessively.
Correct valve seat surface.
+When repairing valve seat, check valve and valve guide for
wear beforehand. If worn, replace them. Then correct valve
seat.
+Cut with both hands to uniform the cutting surface.
SEM872
SEM720B
SEM721B
SEM722B
CYLINDER HEAD
Inspection (Cont'd)
EM-33

VALVE SEAT REPLACEMENT
1. Bore out old seat until it collapses.
The machine depth stop should be set so that boring cannot
continue beyond the bottom face of the seat recess in cylinder
head.
2. Ream the cylinder head recess.
Reaming bore for service valve seat
[Oversize 0.5 mm (0.020 in)]:
Intake
40.954 - 40.932 mm (1.6124 - 1.6115 in)
Exhaust
34.954 - 34.932 mm (1.3761 - 1.3753 in)
Reaming should be done to the concentric circles around the
valve guide center so that valve seat will have the correct ®t.
3. Heat cylinder head to a temperature of 150 to 160ÉC (302 to
320ÉF) and press ®t seat until it seats on the bottom.
4. Install valve seat.
When replacing valve seat, valve should also be replaced.
5. Cut or grind valve seat using suitable tool at the speci®ed
dimensions as shown in SDS.
The cutting should be done with both hands for uniform cut-
ting.
6. Apply small amount of ®ne grinding compound to valve contact-
ing face and put valve into guide.
Lap valve against its seat until proper valve seating is obtained.
Remove valve and then clean valve and valve seat.
SEM795A
SEM008A
SEM876
SEM877
CYLINDER HEAD
Inspection (Cont'd)
EM-34