Isuzu N-Series. Service manual — part 329
6A-58 ENGINE MECHANICAL
3. Use a feeler gauge to measure the piston ring gap.
If the measured valve exceeds the specified limit,
the piston ring must be replaced.
Piston Ring and Piston Ring Groove Clearance
1. Use a feeler gauge to measure the clearance be-
tween the piston ring and the piston ring groove at
several points around the piston.
2. Visually inspect the piston ring grooves.
If a piston ring groove is damaged or distorted, the
piston must be replaced.
Piston Pin
Piston Pin Diameter
Use a micrometer to measure the piston pin outside di-
ameter at several points.
If the measured value is less than the specified limit, the
piston pin must be replaced.
Piston Ring Gap / 4HF1 / 4HF1-2
mm (in)
Standard
Limit
1st compression
ring gap
0.24 — 0.39
(0.0094 — 0.0153)
1.50
(0.0591)
2nd compression
ring gap
0.35 — 0.50
(0.0138 — 0.0197)
Oil ring gap
0.02 — 0.40
(0.0008 — 0.0157)
Piston Ring Gap / 4HG1 / 4HG1-T
mm (in)
Standard
Limit
1st compression
ring gap
0.24 — 0.39
(0.0094 — 0.0153)
1.50
(0.0591)
2nd compression
ring gap
0.35 — 0.50
(0.0138 — 0.0197)
Oil ring gap
0.15 — 0.35
(0.00591 —
0.0138)
Piston Ring Gap / 4HE1-TC
mm (in)
Standard
Limit
1st compression
ring gap
0.24 — 0.40
(0.0094 — 0.0157)
1.50
(0.0591)
2nd and 3rd com-
pression ring gap
0.30 — 0.450
(0.0118 — 0.0177)
Oil ring gap
0.20 — 0.40
(0.0078 — 0.0157)
N6A0259E
Piston Ring and Piston Ring Groove
Clearance / 4HF1, 4HF1-2, 4HG1,
4HG1-T
mm (in)
Standard
Limit
1st Compression
Ring
0.062 — 0.092
(0.0024 — 0.0036)
0.20
(0.0079)
2nd Compression
Ring
0.04 — 0.08
(0.0015 — 0.0031)
0.15
(0.0059)
Oil ring gap
0.02 — 0.06
(0.0008 — 0.0024)
Groove Clearance / 4HE1-TC
mm (in)
Standard
Limit
1st Compression
Ring
0.09 — 0.13
(0.0035 — 0.0051)
0.20
(0.0078)
2nd and 3rd Com-
pression Ring
0.09 — 0.13
(0.0035 — 0.0051)
Oil ring gap
0.03 — 0.07
(0.0012 — 0.0028)
0.15
(0.0059)
N6A0260E
ENGINE MECHANICAL 6A-59
Piston Pin Hole and Piston Pin Clearance
Use an inside dial indicator to measure the piston pin
hole (in the piston).
If an inside dial indicator is not available, use the follow-
ing procedure to check the piston pin clearance.
1. Use a piston heater to heat the piston to approxi-
mately 80 — 100
°C (176 — 212°F)
2. Push strongly against the piston pin with your
thumbs. The piston pin should move smoothly with
little or no resistance.
Connecting Rod
Connecting Rod Alignment
Use a connecting rod aligner to measure the distortion
and the parallelism between the connecting rod big end
hole and the connecting rod small end hole.
If either the measured distortion or parallelism exceeds
the specified limit, the connecting rod must be replaced.
Piston Pin Diameter
mm (in)
Engine model
Standard
Limit
Except 4HE1-
TC
35.995 —
36.000 (1.4171
— 1.4173)
35.970 (1.4161)
4HE1-TC
39.995 —
40.000 (1.5746
— 1.5748)
39.970 (1.5736)
Piston Pin Hole and Pis-
ton Pin Clearance
mm (in)
Standard
Limit
0.004 — 0.017 (0.00016
— 0.00067)
0.04 (0.0016)
N6A0261E
N6A0262E
Connecting Rod Alignment
mm (in)
Per Length of 100 (3.94)
Standard
Limit
Distortion
0.05 (0.002) or
less
0.20 (0.008)
Parallelism
N6A0263E
6A-60 ENGINE MECHANICAL
Piston Pin and Connecting rod Small End Bushing
Clearance
Use a caliper calibrator and a dial indicator to measure
the clearance between the piston pin and connecting
rod small end bushing.
If the clearance between the piston pin and the connect-
ing rod small end bushing exceeds the specified limit,
replace the piston pin and/or the connecting rod bush-
ing.
Connecting Rod Bushing Replacement
Connecting Rod Bushing Removal
1. Set the collar (1), the connecting rod (2), and the
collar (3) to the setting bar (4).
Connecting Rod Bushing Replacer: 5-8840-2340-0
2. Hand-tighten the nut (5) until there is no more gap.
3. Set the connecting rod bushing replacer base (6) to
the bench press.
4. Set the connecting rod to the connecting rod bush-
ing replacer base.
5. Tighten the bolt (7).
6. Use the bench press to force the bushing from the
connecting rod.
Connecting Rod Bushing Installation
1. Set the connecting rod bushing replacer base (1) to
the bench press.
Connecting Rod Bushing Replacer: 5-8840-2340-0
2. Set the connecting rod to the connecting rod re-
placer base.
The connecting rod must be perfectly horizontal.
3. Tighten the bolt (2) to hold the connecting rod small
end in place.
Piston Pin and Connect-
ing Rod Small End Bush-
ing Clearance
mm (in)
Standard
Limit
0.012 — 0.027 (0.0005
— 0.0011)
0.05 (0.002)
N6A0264E
N6A0265E
N6A0266E
N6A0267E
ENGINE MECHANICAL 6A-61
4. Install the two collars (3) and the new bushing (4)
to the setting bar (5).
Align the bushing clinch line and the collar setting
marks.
Tighten the nut (6).
5. Use the bench press to press the new bushing into
position inside the connecting rod.
Check that the bushing oil holes and the connect-
ing rod oil holes are aligned.
6. Use a pinhole grinder to finish the new bushing.
Reassembly
1. Piston
2. Piston Pin Snap Ring
Use a pair of snap ring pliers to install the piston pin
snap ring to the piston.
3. Connecting Rod
1) Clamp the connecting rod in a vise.
Take care not to damage the connecting rod.
2) Install the connecting rod so that the piston
head front mark (1) and the connecting rod
forging mark (projecting) (2) are set in the same
direction.
Connecting Rod Small
End Bushing Inside
Diameter
mm (in)
Except 4HE1-TC
36.012 — 36.022
(1.4178 — 1.4182)
4HE1-TC
40.012 — 40.022
(1.5753 — 1.5767)
N6A0268E
N6A0269E
N6A0270E
N6A0271E
Нет комментариевНе стесняйтесь поделиться с нами вашим ценным мнением.
Текст