Isuzu N-Series. Service manual — part 592
6A1-56 4JB1/4JB1-TC/4JG2/4JH1-TC - ENGINE
10) Oil level gauge guide tube
11) Oil cooler water pipe (Oil Cooler Model)
12) A/C compressor assembly (A/C Model)
13) Vacuum actuator hose (Exhaust Brake Model)
14) Front exhaust pipe
15) By-pass hose
16) Cylinder head cover
17) Rocker arm shaft
18) Push rod
19) Cylinder head assembly
20) Cylinder head gasket
Above works refer to “CYLINDER HEAD AS-
SEMBLY AND GASKET” Section in this manu-
al.
2. Oil Pan Assembly
1) Vacuum pump oil hose
2) Engine mount bolt
3) Stiffener and spacer rubber
4) Oil pan
Above works refer to “OIL PAN” Section in this
manual.
3. Oil Pump Assembly
4. Piston Cooling Oil Pipe
• Remove the relief valve and oil pipe.
5. Connecting Rod Bearing Cap
• If the connecting rod lower bearings are to be rein-
stalled, mark their fitting positions by tagging each
bearing with the cylinder number from which it was
removed.
6. Piston and Connecting Rod Assembly
1) Remove carbon deposits from the upper por-
tion of the cylinder wall with a scraper before re-
moving the piston and connecting rod.
2) Move the piston to the top of the cylinder and
tap it with a hammer grip or similar object from
the connecting rod lower side to drive it out.
N6A3191E
N6A3307E
N6A3308E
4JB1/4JB1-TC/4JG2/4JH1-TC - ENGINE 6A1-57
3) If the connecting rod upper bearings are to be
reinstalled, mark their fitting positions by tag-
ging each bearing with the cylinder number
from which it was removed.
4) Clamp the connecting rod in a vise.
Take care not to damage the connecting rod.
Use a piston ring replacer to remove the piston
rings.
Piston Ring Replacer
Do not attempt to use some other tool to re-
move the piston rings. Piston ring stretching will
result in reduced piston ring tension.
5) Use a pair of pliers to remove the piston pin
snap rings.
6) Tap the piston pin out with a hammer and a
brass bar. If the pistons and piston pins are to
be reinstalled, mark their installation positions
by tagging each piston and piston pin with the
cylinder number from which it was removed.
N6A3309E
N6A3310E
N6A3172E
N6A3173E
6A1-58 4JB1/4JB1-TC/4JG2/4JH1-TC - ENGINE
Installation
1. Piston and Connecting Rod Assembly
1) Try to insert the piston pin into the piston pin
hole with normal finger pressure.
Weigh each piston and connecting rod assem-
bly.
Select piston and connecting rod combinations
so that the weight variation of the different as-
semblies is held within the specified limits.
2) Clamp the connecting rod in a vise.
Take care not to damage the connecting rod.
3) Use a pair of pliers to install the piston pin snap
ring to the piston.
Notice:
When changing piston/connecting rod combinations, do
not change the piston/piston pin combination.
4) Install the piston to the connecting rod.
The piston head front mark (1) and the connect-
ing rod “ISUZU” casting mark (2) must be fac-
ing the same direction.
5) Apply a coat of engine oil to the piston pin and
the piston pin hole.
Use your fingers to force the piston pin into the
piston until it makes contact with the snap ring.
6) Use your fingers to force the piston pin snap
ring into the piston snap ring groove.
Check that the connecting rod moves smoothly
on the piston pin.
g (oz)
Variance in weight
Less than
after assembly
3 (0.1058)
N6A3311E
N6A3173E
N6A3205E
N6A3206E
4JB1/4JB1-TC/4JG2/4JH1-TC - ENGINE 6A1-59
7) Install the piston rings with the piston ring ex-
pander.
The compression ring must be set with the 1N,
2N, R mark facing up.
Discrimination mark is painted as shown in the
illustration.
8) Use a piston ring replacer to install the three
piston rings.
Piston Ring Replacer
Install the piston rings in the numerical order
shown in the illustration.
4JH1-TC, 4JB1
4JG2
Notice:
Install the compression rings with the stamped side fac-
ing up.
Insert the expander coil into the oil ring groove so that
there is no gap on either side of the expander coil before
installing the oil ring.
9) Apply engine oil to the piston ring surfaces.
Legend
1. N mark (Top ring) (2nd ring) (4JB1)
2. 1N mark (Top ring) 2N mark (2nd ring) (4JG2)
3. R mark (Top ring) (2nd ring) (4JH1-TC)
N6A3207E
N6A3178E
Legend
1. Oil ring
2. 2nd compression ring
3. 1st compression ring
Legend
1. Oil ring
2. Compression ring No. 2
3. Compression ring No. 1
N6A3188E
N6A3189E
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