Isuzu N-Series. Manual — part 359
6A3-88 ENGINE (4HF1 / 4HF1-2 / 4HE1-TC / 4HG1 / 4HG1-T)
PISTON, PISTON RING, PISTON PIN AND CONNECTING ROD
Component
Removal
Preparation
• Disconnect battery ground cable.
• Tilt the cab.
• Drain coolant and engine oil.
1. Nozzle Cover
2. Spacer Rubber
Remove the stiffener before removing the spacer
rubber.
3. Oil Pan
4. Oil Pump Strainer
Legend
1. Nozzle cover
9. Camshaft bearing cap
2. Spacer rubber
10. Camshaft bearing upper
3. Oil pan
11. Camshaft assembly
4. Oil pump strainer
12. Camshaft bearing lower
5. Cylinder head cover
13. Cylinder head assembly
6. Cylinder head cover gasket
14. Cylinder head gasket
7. Rocker arm shaft assembly
15. Connecting rod cap
8. Valve cap
16. Piston and connecting rod assembly
N6A0571E
ENGINE (4HF1 / 4HF1-2 / 4HE1-TC / 4HG1 / 4HG1-T) 6A3-89
5. Cylinder Head Cover
6. Cylinder Head Cover Gasket
7. Rocker Arm Shaft Assembly
Above works refer to “ROCKER ARM SHAFT AS-
SEMBLY” section in this manual.
8. Valve Cap
Caution:
Take sufficient care not to let valve caps fall into the gear
case or oil return hole.
9. Camshaft Bearing Cap
10. Camshaft Bearing Upper
11. Camshaft Assembly
12. Camshaft Bearing Lower
Above works refer to “CAMSHAFT ASSEMBLY”
section in this manual.
13. Cylinder Head Assembly
Above works refer to “CYLINDER HEAD” section
in this manual.
14. Cylinder Head Gasket
Caution:
Do not reuse the cylinder head gasket.
15. Connecting Rod Cap
1) Take out the connecting rod bearing cap bolts
and remove the bearing cap with the lower
bearing.
2) If the connecting rod lower bearings are to be
reinstalled, mark their fitting positions by tag-
ging each bearing with the cylinder number
from which it was removed.
16. Piston and Connecting Rod Assembly
1) To facilitate smooth removal of piston, remove
carbon from the upper part of the cylinder wall
using a scraper or equivalent.
N6A0193E
N6A0422E
N6A0196E
6A3-90 ENGINE (4HF1 / 4HF1-2 / 4HE1-TC / 4HG1 / 4HG1-T)
2) Remove the piston and connecting rod assem-
bly upward by pushing on the edge of the con-
necting rod with a hammer handle or
equivalent.
3) If the connecting rod bearing are to be rein-
stalled, mark their fitting positions by tagging
each bearing with the cylinder number from
which it was removed.
Caution:
Do not bend or damage the oiling jet.
Notice:
When removing the piston and connecting rod assem-
bly, pull the connecting rod in parallel with the cylinder
bore.
Installation
1. Piston and Connecting Rod Assembly
Notice:
When installing new connecting rod and/or connecting
rod bearings, refer to the selection table. Above works
refer to “CRANKSHAFT” section 6A in this manual.
1) Apply a coat of engine oil to the circumference
of each piston ring and piston.
2) Position the piston ring gaps as shown in the il-
lustration.
3) Apply a coat of molybdenum disulfide grease to
the two piston skirts.
This will facilitate smooth break-in when the en-
gine is first started after reassembly.
4) Apply a coat of engine oil to the upper bearing
surfaces.
5) Apply a coat of engine oil to the cylinder wall.
6) Position the piston head front mark so that it is
facing the front of the engine.
7) Use the piston ring compressor to compress
the piston rings.
Piston Ring Compressor: 5-8840-9018-0
N6A0197E
Legend
1. 1st compression ring
2. 2nd compression ring
3. 3rd compression ring (4HE1-TC only)
4. Oil ring
5. Coil expander
6. Front mark
N6A0576E
N6A0577E
ENGINE (4HF1 / 4HF1-2 / 4HE1-TC / 4HG1 / 4HG1-T) 6A3-91
8) Use a hammer grip to push the piston in until
the connecting rod makes contact with the
crankpin.
At the same time, rotate the crankshaft until the
crankpin is at bottom dead center.
Caution:
Do not bend or damage the oiling jet.
2. Connecting Rod Cap
1) Install the connecting rod bearing caps.
2) Align the bearing cap cylinder number marks
and the connecting rod cylinder number marks.
3) Apply a coat of molybdenum disulfide grease to
the threads and setting faces of each connect-
ing rod cap bolts.
4) Tighten the connecting rod caps to the speci-
fied torque.
Tighten:
Connecting rod bearing cap bolt to
• 1st step: 39 N
⋅m (4.0 kg⋅m/29 lb⋅ft)
• 2nd step: 60
°
• 3rd step: 30
°
Angle gauge: 5-8840-0266-0
3. Cylinder Head Gasket
Above works refer to “CYLINDER HEAD” section
in this manual.
4. Cylinder Head Assembly
Above works refer to “CYLINDER HEAD” section
in this manual.
5. Camshaft Bearing Lower
6. Camshaft Assembly
7. Camshaft Bearing Upper
8. Camshaft Bearing Cap
9. Valve Cap
Above works refer to “CAMSHAFT ASSEMBLY”
section in this manual.
10. Rocker Arm Shaft Assembly
Above works refer to “ROCKER ARM SHAFT AS-
SEMBLY” section in this manual.
11. Cylinder Head Cover Gasket
Above works refer to “CYLINDER HEAD” section
in this manual.
12. Cylinder Head Cover
Above works refer to “CYLINDER HEAD COVER”
section in this manual.
13. Oil Pump Strainer
Install the O-ring (1) to the oil pump strainer pipe
and install the oil pump strainer to the cylinder body
shown in the illustration.
Tighten:
Oil pump strainer bolt to 24 N
⋅m (2.4 kg⋅m/17 lb⋅ft)
Legend
1. Alighment
2. Boss discriminating the front from rear
N6A0279E
N6A0280E
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