Isuzu N-Series. Manual - part 569

GENERAL ENGINE MECHANICAL 6A-33

Measure the diameter and the uneven wear of
main journal and crank pin.
If the crankshaft wear exceeds the specified
limit, crankshaft must be replaced.

Crankshaft Inspection
Inspect the surface of the crankshaft journals and crank
pins for excessive wear and damage.
Inspect the oil seal fitting surfaces for excessive wear
and damage.
Inspect the oil ports for obstructions.

Crankshaft Tufftriding Inspection
The portion to be tested must be held horizontally so as
not let the test solution flow (1).
Test liquid should not be applied to the area around the
oil port (2).
Approximately 10 mm (0.39 in) (3)
The sliding surface of the pin or journal (4).

Notice:
To increase crankshaft strength, Tufftride Method (Soft
nitriding) has been applied. Because of this, it is not pos-
sible to regrind the crankshaft surfaces.

1. Use an organic cleaner to thoroughly clean the

crankshaft. There must be no traces of oil the sur-
faces to be inspected.

2. Prepare a 5 — 10% solution of ammonium cupric

chloride (dissolved in distilled water).

3. Use a syringe to apply the solution to the surface to

be inspected.
Hold the surface to be inspected perfectly horizon-
tal to prevent the solution from running.

Notice:
Do not allow the solution to come in contact with the oil
ports and their surrounding area.

Testing

1. Wait for thirty to forty seconds.

If there is no discoloration after thirty or forty sec-
onds, the crankshaft is usable.
If discoloration appears (the surface being tested
will become the color copper), the crankshaft must
be replaced.

2. Steam clean the crankshaft surface immediately

after completing the test.

Notice:
The ammonium cupric chloride solution is highly corro-
sive. Because of this, it is imperative that the surfaces
being tested be cleaned immediately after completing
the test.

mm (in)

Standard

Limit

Main journal
diameter

69.917 — 69.932 

(2.7526 — 2.7532)

69.91 (2.7524)

Crank pin
diameter

52.915 — 52.930 

(2.0833)

52.90 (2.0843)

Uneven
wear limit

0.05 (0.0020) or 

less

0.08 (0.0031)

N6A3134E

N6A3135E

N6A3136E

6A-34 GENERAL ENGINE MECHANICAL

Crankshaft Bearing Selection
When installing new crankshaft bearings or replacing
old bearings, refer to the selection table.

Notice:
Please note that some Crankshaft No. 4 journals made
during a limited production period have their number
(No. 4) marked on either their front or rear side of webs
as shown below.

Notice:
Although all upper journal bearings (cylinder body side)
have oil grooves and holes, all lower bearings (bearing
cap side) have no groove and hole.
Play close attention to the distinction during the installa-
tion procedure.

N6A3137E

N6A3138E

N6A3139E

GENERAL ENGINE MECHANICAL 6A-35

Reassembly

1. Crankshaft

• Install the main bearings to the cylinder body

and the main bearing caps.

• Be sure that they are positioned correctly.
• Apply new engine oil to the upper and lower

main bearing faces.

• Carefully mount the crankshaft.
• Apply engine oil to the thrust washer.
• Assemble the thrust washer to the No.3 bear-

ing journal. The oil grooves must face the
crankshaft.

2. Main Bearing Cap

• Apply the recommended liquid gasket or its

equivalent to the No. 5 crankshaft bearing cap
(1) as shown in the illustration.

• Install the arch gasket (2) to the No. 5 bearing

cap.
Use your fingers to push the arch gasket into
the bearing cap groove.

mm (in)

Crankshaft Bearing Housing

Crankshaft Journal

Crankshaft Bearing 

Size Code

Grade Mark

Diameter

Grade Mark

Diameter

1

73.992 — 74.000

(2.9131 — 2.9134)

1 or -

69.927 — 69.932 

(2.7530 — 2.7532)

4

2 or - -

69.922 — 69.927 

(2.7528 — 2.7530)

3 or - - -

69.917 — 69.922 

(2.7556 — 2.7528)

5

2

73.983 — 73.992

(2.9127 — 2.9131)

1 or -

69.927 — 69.932 

(2.7530 — 2.7532)

2

2 or - -

69.922 — 69.927 

(2.7528 — 2.7530)

3

3 or - - -

69.917 — 69.922 

(2.7556 — 2.7528)

4

3

73.975 — 73.983

(2.9124 — 2.9127)

1 or -

69.927 — 69.932 

(2.7530 — 2.7532)

1

2 or - -

69.922 — 69.927 

(2.7528 — 2.7530)

2

3 or - - -

69.917 — 69.922 

(2.7526 — 2.7528)

N6A3140E

N6A3141E

6A-36 GENERAL ENGINE MECHANICAL

Notice:
Be sure that the bearing cap fitting surface is completely
free of oil before applying the liquid gasket.
Do not allow the liquid gasket to obstruct the cylinder
thread holes and bearings.

• Install the bearing caps with the bearing cap

head arrow mark facing the front of the engine.

• Apply engine oil to the crankshaft bearing cap

bolts.

• Tighten the crankshaft bearing cap bolts to the

specified torque a little at a time in the se-
quence shown in the illustration.

Tighten:
167 N

⋅m (17 kg⋅m/123 lb⋅ft)

Notice:
Check to see that the crankshaft turns smoothly by ro-
tating it manually.

3. Crankshaft Rear Oil Seal (Gear and Belt Drive

Model)
Use the oil seal installer to install the oil seal to the
cylinder body.
Installer: Rear Oil Seal 5-8840-2359-0

Notice:
Wipe off rust and scraps clean from the press-in portion
of the oil seal.
Take note of the press-in direction of the oil seal.

1) Install the adapter of the special tool to the rear

end of the crankshaft with two bolts.

2) Install the oil seal to the outer circumference of

the adapter.

3) Insert the slave into the adapter portion, and

tighten it in with the bolt (M12 

× 1.75L=70) until

the adapter section hits the slave.

4) Remove the adapter and the slave.
5) After installing the oil seal, check the measure-

ment of the oil seal.

N6A3142E

N6A3143E

Standard

mm (in)

12.2 — 12.8 (0.48 — 0.50)

N6A3144E