Isuzu N-Series. Manual - part 641

ENGINE EXHAUST 6F-3

THREE WAY CATALYTIC CONVERTER

The three way catalytic converter is an emission control
device added to the exhaust system to reduce pollutants
from the exhaust gas stream.

Caution:
The catalytic converter requires the use of unleaded fuel
only.

Periodic maintenance of the exhaust system is not re-
quired. If the vehicle is raised for other service, it is ad-
visable to check the condition of the complete exhaust
system.
A dual bed monolith catalytic converter is used in com-
bination with three way catalytic converter.
Catalytic Types:
Three way (Reduction/Oxidation) catalyst
The catalyst coating on the three way (reduction) con-
verter contains platinum and rhodium which lowers the
levels of oxide of nitrogen (NOx) as well as hydrocar-
bons (CH) and carbon monoxide (Co).

On-Vehicle Service

Rattles and noise vibrations in the exhaust system are
usually caused by misalignment of parts. When aligning
the system, leave all bolts or nuts loose until all parts are
properly aligned; then tighten, working from front to rear.

1. Check connections for looseness or damage, es-

pecially for exhaust gas leakage.

2. Check clamps and rubbers for weakness, cracks or

damage.

3. If any part of the converter heat shield is damaged

or dented to the extent that it contacts the catalyst,
repair or replace.

4. Check for dents or damage and for any holes or

cracks caused by corrosion.

N6A3594E

6F-4 ENGINE EXHAUST

FRONT EXHAUST PIPE

Component

Removal

Preparation

• Battery ground cable

1. Exhaust manifold fixing nuts.

• Remove two fixing nuts from exhaust manifold and

front pipe.

2. Front exhaust pipe mounting bracket fixing bolt and

nut.

3. Front exhaust pipe fixing bolts and nuts.

• Remove two bolts fixed from front pipe and center

pipe.

4. Front exhaust pipe.

• Take out the exhaust pipe to another side.

Installation

1. Front exhaust pipe.
2. Front exhaust pipe fixing bolts and nuts.

• Tighten the fixing nuts to the specified torque

Tighten:

• 50  N

⋅m (5.1 kg⋅m / 37 lb⋅ft)

3. Front exhaust pipe mounting bracket fixing bolt and

nut.

• Tighten the fixing bolt to the specified torque

Tighten:

• 40  N

⋅m (4.1 kg⋅m / 30 lb⋅ft)

4. Exhaust manifold fixing nuts

• Tighten the fixing nuts to the specified torque

Tighten:

• 69  N

⋅m (7 kg⋅m / 51 lb⋅ft)

Legend

1. Exhaust manifold fixing washer and nut.

3. Front exhaust pipe fixing nut.

2. Front exhaust pipe mounting bracket fixing bolt 

and nut.

4. Front exhaust pipe.

N6A3595E

N6A3596E

ENGINE EXHAUST 6F-5

• Connect battery ground cable.
• After assembling each part, start the engine to

check for any leakage of gas at each connection.

N6A3597E

6F-6 ENGINE EXHAUST

EXHAUST BRAKE UNIT

Inspection

Operational Inspection

• With the engine idling, operate the exhaust brake

to check for the sound of the valve hitting against
the stopper.

Unit Inspection

• Check to see if the exhaust valve opens and closes

smoothly when the power chamber is applied with
a negative pressure (400 mmHg — 700 mmHg) by
the vacuum pump.

• Check to see if the clearance between the valve

and the body is in the range of 0.1 mm — 0.2 mm
(the minimum of 0.1 mm) on an average of the
points “A” and “B” when the power chamber is ap-
plied with a negative pressure (650 mmHg — 700
mmHg) by the vacuum pump.
When the clearance is outside this range, adjust
the clearance with the adjust bolt.

N6A3598E

N6A3599E