Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual — part 548

6A – 30 ENGINE MECHANICAL

Thermostat Operating Test

1. Completely submerge the thermostat in water.
2. Heat

the

water.

Stir the water constantly to avoid direct heat being
applied to the thermostat.

3. Check the thermostat initial opening temperature.
Thermostat Initial Opening Temperature

°C (°F)

82 (180)

4. Check the thermostat full opening temperature.
Thermostat Full Opening Temperature

°C (°F)

95 (203)

Valve Lift at Fully Open position

mm (in)

9.5 (0.37)

Q

Thermometer

R

Agitating rod

S

Wooden piece

ENGINE MECHANICAL 6A – 31

Drive Belt Adjustment

Depress the drive belt mid-portion with a 10 kg (22 lb/98N)
force.
Drive Belt Deflection

mm (in)

10 (0.39)

Check the drive belt for cracking and other damage.

Q

Crankshaft damper pulley

R

Generator pulley

S

Cooling fan pulley

T

Oil pump pulley or idler pulley

U

Compressor pulley or idler pulley

Cooling Fan Pulley Drive Belt

Fan belt tension is adjusted by moving the generator.
Depress the drive belt mid-portion with a 10 kg (22 lb/98N)
force.
Drive Belt Deflection

mm (in)

10 (0.39)

Q

Crankshaft damper pulley

R

Generator pulley

S

Cooling

fan pulley

Compressor Pulley Drive Belt

Move the idler pulley as required to adjust the compressor
drive belt tension.
If the vehicle is equipped with power steering, move the oil
pump as required
Depress the drive belt mid-portion with a 10 kg (22 lb/98
N) force.
Belt Deflection

mm (in)

12 – 15 (0.47 – 0.59)

Q

Crankshaft damper pulley

R

Oil pump pulley or idler pulley

6A – 32 ENGINE MECHANICAL

Power Steering Oil Pump Pulley Drive Belt

Move the oil pump as required to adjust the oil pump drive
belt tension.
On air conditioner equipped models, both drive belts pulley
must always be replaced as a set.
Depress the drive belt mid-portion with a 10 kg (22 lb/98
N) force.
Belt Deflection

mm (in)

14 - 17 (0.55 – 0.67)

Q

Crankshaft damper pulley

R

Oil pump pulley

S

Compressor pulley or idler pulley

ENGINE CONTROL

Idling Speed Adjustment

1. Set the vehicle parking brake and chock the drive

wheels.

2. Place the transmission in neutral.
3. Start the engine and allow it to idle until the coolant

temperature reaches 70 - 80

°C (158 - 176°F).

4. Disconnect the engine control cable from the control

lever.

5. Set a tachometer to the engine.
6. Check the engine idling speed.

If the engine idling speed is outside the specified
range, it must be adjusted.

Engine Idling Speed

rpm

4JA1, 4JB1

750

± 50

4JA1T

770

± 50

4JG2T

720

± 50

4JA1TC

730

± 25

4JH1TC

700

± 25

Idling Speed Adjustment

(Except 4JA1TC, 4JH1TC)

1. Loosen the idling set screw lock nut

Q

on the injection

pump idling set bolt.

2. Adjust the idling speed to the specified range by

turning the idling set bolt

R

.

3. Lock the engine set nut

Q

with the idling set bolt lock

nut.

4. Check that the idling control cable is tight (free of

slack). If required, remove the slack from the cable.

ENGINE MECHANICAL 6A – 33

Fast Idling Speed Inspection

1. Set tachometer to the engine.
2. Disconnect the vacuum hose

Q

from the fast idle

actuator

U

on the injection pump.

3. Disconnect the other vacuum hose

R

from the

vacuum switching valve

S

and connect it to the fast

idle actuator

U

.

The vacuum line will now be connected directly from
the vacuum pump

T

to the fast idle actuator.

4. Check the engine fast idling speed.

If the engine idling speed is outside the specified
range, it must be adjusted.

Fast Idling Speed

rpm

850 - 950

Fast Idling Speed Adjustment

1. Loosen the fast idle actuator bracket bolts.

1. Adjust the fast idling speed by moving the actuator

bracket, so that the clearance “S” can be 1 ~ 2 mm
(0.04 ~ 0.08 in.).

2. Tighten the bracket bolts.

Accelerator Control
Accelerator Control Cable Adjustment

1. Loosen the accelerator cable clamp bolt

Q

.

2. Check that the idling control knob is in the engine

idling position.

3. Hold the accelerator lever

R

in the fully closed

position and stretch the control cable

S

in the

direction indicated by the arrow to remove any slack.

101RY00014