Isuzu KB P190. Manual — part 353

6A-52 ENGINE MECHANICAL (4JK1/4JJ1)

LTW56ASH000101

8. Remove the vacuum pump.

• Remove the vacuum pipe bracket and vacuum

pipe.

• Remove the oil pipe (feed side and return side)

of vacuum pump.

RTW76ASH000201

9. Remove the front cover.

RTW56ASH019701

10. Install the M6 bolt to the idle gear A.

11. Remove the idle gear A and idle gear A flange, idle

gear A shaft.

RTW56ASH011301

ENGINE MECHANICAL (4JK1/4JJ1) 6A-53

12. Remove the idle gear C and idle gear C shaft.

RTW56ASH011401

13. Remove the crankshaft gear.

RTW56ASH021501

Disassembly

1. Remove the scissor gear assembly.

• Clamp the vise. Insert soft metal protectors

(aluminum) between the vise and component.

Use a pair of snap ring pliers to remove the

scissor gear assembly.

RTW56ASH022001

Legend

1. Snap

Ring

2. Sub-gear

3. Spring

4. Idle Gear A

Reassembly

1. Install the scissor gear assembly.

• Clamp the vise. Insert soft metal protectors

(aluminum) between the vise and component.

Press against the pin on the left side of the idle

gear A spring to make a gap on the right side of

the spring. Push the spring into place.

6A-54 ENGINE MECHANICAL (4JK1/4JJ1)

• Align the sub gear pin with the hole in the right

side of the idle gear A spring. Press the sub-

gear into place.

RTW56ASH022001

Legend

1. Snap

Ring

2. Sub-gear

3. Spring

4. Idle Gear A

• Use a pair of snap ring pliers to snuggly install

the snap ring.

Inspection

1. Measurement of idle gear backlash

• Apply a dial gauge on the teeth of the idle gear

to be measured and move the gear to right and

left lightly to read how much the dial gauge

shook (never fail to fix the gear).

• If the measurement exceeds the limit, replace

the idle gear.

Backlash of the idle gear

mm (in)

Standard 0.10

− 0.17 (0.004 − 0.006)

Limit 0.30

(0.01)

• Measure backlash of the idle gear before

removing the idle gear A.

2. Measurement of end clearance of the idle gear.

• Insert a thickness gauge between the idle gear

and the thrust collar to measure a clearance.

• If the measurement exceeds the limit, replace

either the idle gear or the thrust collar.

End clearance of the idle gear

mm (in)

Standard 0.080

− 0.155 (0.003 − 0.006)

Limit 0.20

(0.008)

• Measure an end clearance of the idle gear

before removing the idle gear B.

3. External diameter of the idle gear shaft.

• Use a micrometer to measure an external

diameter of each idle gear shaft.

• If the measurement exceeds the limit, replace

the shaft.

External diameter of the idle gear A shaft

mm (in)

Standard 44.950

− 44.957 (1.7697 − 1.7700)

Limit 44.80

(1.764)

External diameter of the idle gear C shaft

mm (in)

Standard 24.959

− 24.980 (0.9826 − 0.9835)

Limit 24.80

(0.976)

RTW56ASH021601

4. Clearance between the idle gear and the idle gear

shaft
• Measure an inside diameter of the idle gear

bush to calculate a clearance between the idle

gear and the idle gear shaft.

ENGINE MECHANICAL (4JK1/4JJ1) 6A-55

• If the measurement exceeds the limit, replace

either the idle gear or the shaft.

Clearance between the idle gear A and the shaft

mm

(in)

Standard 0.020

− 0.062 (0.0007 − 0.0024)

Limit 0.200

(0.0079)

Clearance between the idle gear C and the shaft

mm

(in)

Standard 0.025

− 0.075 (0.0010 − 0.0030)

Limit 0.200

(0.0079)

LNW21BSH003601

Installation

1. Install the crankshaft gear.

2. Install the idle gear C.

• Apply engine oil over the part where the gear of

the idle gear shaft is to be put together.

• Apply engine oil to the bolt screw thread and

seat, and temporarily tighten together with the

flange (tighten fully in later process).

RTW56ASH011401

3. Install the idle gear A.

4. Tighten sub gear setting bolt.

• Use the M6 bolts and lever to turn sub gear to

right direction until it aligns with the M6 bolt

hole between idle gear A and sub gear.

• Tighten the M6 bolt to a suitable torque to

prevent the sub gear from moving.

RTW56ASH011501