Isuzu N-Series. Manual — part 495

Engine Mechanical (4HK1-TC) 6A-85

• Use a seat cutter to minimize the scratch and

other roughness (15/45/75 degree-blade),
thereby returning the contact width to the
standard value.

Caution:
Remove only scratches and roughness, and do not cut
the surface too much.
Use the free adjustment valve cutter pilot.
Do not let the valve cutter pilot waver inside the valve
guide.

• Attach abrasives in the valve insert seat.
• Insert the valve into the valve guide.
• Attach abrasives on the valve seat surface,

rotate the valve and hit it lightly to grind them,
and confirm that it has even contact all round.

Caution:
Remove abrasives completely after grinding.

Replace the valve seat insert
Remove the valve seat insert

• Arc-weld the entire inner diameter of the valve

seat insert.

• Cool the valve seat insert for two to three

minutes. Contraction fur to cooling makes it
easier to remove the valve seat insert.

• Remove the valve seat insert, using a screw

driver. Be sure not to damage the cylinder
head.

Legend

1. Arc-weld
2. Valve Seat Insert
3. Screw Driver

Install the valve seat insert

• Carefully place an attachment (the outer

diameter is smaller than the valve seat insert)
on the valve seat insert.

• Use the press to apply pressure gradually on

the washer, thereby pushing the valve seat
insert.

N6A6153E

N6A6154E

N6A6155E

N6A6156E

6A-86 Engine Mechanical (4HK1-TC)

Caution:
Do not apply too much pressure with the press.
Attach compound on the valve seat surface, rotate the
valve and hit it lightly to grind them, and confirm that it
has even contact all round.

Legend

1. Attachment
2. Valve Seat Insert
3. Press

Reassembly

1. Install the oil seal.

• Install on the surface of injection pipe insert.
• Hammer it in so that the seal does not incline.

Caution:
Be sure not to damage the rip.

Special tool
Oil seal installer: 5-8840-2627-0 (J-43269)

Legend

1. Cylinder Head
2. Oil Seal Installer

2. Install the bridge guide.

• Apply engine oil on the outer diameter of the

guide, then use the installer to hammer it into
the depth of the finishing part of the hole of the
cylinder head.
(Note: the height of the bridge guide is about
37.5 mm (1.48 in) from the upper surface of the
head)

Special tool
Bridge guide installer: 5-8840-2626-0 (J-43268)

Legend

1. 122.5

± 0.5 mm (4.82 ± 0.02 in)

2. 37.5 mm (1.48 in)

3. Install the nozzle sleeve.

• Install the O-ring on the nozzle sleeve, apply

engine oil.

N6A6157E

N6A6139E

N6A6158E

N6A6159E

Engine Mechanical (4HK1-TC) 6A-87

• Apply seal material on the taper section.

Loctite No.TL290

Legend

1. O-ring (White Paint)
2. O-ring
3. Apply the Loctite
4. Engine Oil

• Install the nozzle sleeve on the cylinder head,

insert the guide sleeve.

• Use the guide sleeve to push in so that the

nozzle sleeve fully contacts with the under
surface of the cylinder head.

• Insert the sleeve and fix it with the tighten and

bolt.

• Insert the ball (bearing steel ball 9.525 mm

(0.375 in)) into the guide sleeve, attach the
punch bar and hammer out the ball.

Caution:

• Leave the cylinder head floating so that the ball

comes off from the under surface.

Special tool
Nozzle sleeve installer: 5-8840-2624-0
(J-43266)

Legend

1. Punch Bar
2. Ball
3. Guide Sleeve
4. Nozzle Sleeve
5. Bracket
6. Bolt

4. Install the valve guide.

1

2

3

4

N6A6650E

N6A6161E

6A-88 Engine Mechanical (4HK1-TC)

• Hammer in the valve guide from the upper

surface of the cylinder head, using the valve
guide replacer.

Special tool
Valve guide replacer: 5-8840-2628-0 (J-43272)

Height from the upper surface of the cylinder
head to the edge surface of the valve guide:
18.75 – 19.25 mm (0.7381 – 0.7578 in)

Caution:
When replacing the valve guide, it must be replaced
together with the valve.

5. Install the valve stem oil seal.

• Apply engine oil on the outer diameter of the

valve guide, use the valve stem seal installer to
install the oil seal.

Caution:
After installation of the valve stem seal, confirm that the
oil seal is not inclining and the garter spring is in place.

Special tool
Valve stem seal installer: 5-8840-2833-0
(EN-47685)

6. Install the intake and exhaust valves.

• Apply engine oil on the valve stem part and

install the valve.

7. Install the valve spring.

• Install the valve spring with the paint mark or

the narrower side of the spring pitch on the
under side (the cylinder head side).

N6A6162E

N6A6163E

Paint mark

Intake side

Blue

Exhaust side

Red

N6A6118E

N6A6164E