turbo AUDI TT 1999 8N / 1.G AEB ATW Engines Exhaust System Components Workshop Manual

26-3


5 -
Bolt
25 Nm (18 ft lb)
6 -
Mount
7 -
Gasket Always replace
8 -
Nut Always replace30 Nm (22 ft lb)
9 -
Gasket Always replace
10 -
Turbocharger Removing and installing Page 21
-30
11 -
Three Way Catalytic Converter (TWC)
Protect from damageRemoving and installing Page 26
-21
Disconnect Heated Oxygen Sensor
(HO2S) harness connector Page 26
-21

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26-4


CAUTION!
Part numbers are listed here for reference only.
Always check with your Parts department for
the latest information. 12 -
Heated Oxygen Sensor (HO2S)
50 Nm (37 ft lb)Only grease threads with "G 052 112 A3."
Do NOT allow grease to get into slots on
sensor body

Checking Repair Manual, 1.8 Liter 4-Cyl. 5V
Turbo Fuel Injection &Ignition, Repair Group 24
13 -
Nut
Always replace25 Nm (18 ft lb)
14 -
Bolt 25 Nm (18 ft lb)
15 -
16Mount
Different versions for manual and automatic
transmissions Manual transmission Page 26
-12
, Fig.
1

Automatic transmission Page 26
-13
,
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26-7


All-wheel-drive vehicles

1 -
Front muffler
Factory-installed with rear muffler as one
unit. If repair is necessary, replace
separately Separating point Page 26
-16
Align exhaust system free of stress
Page 26
-24

2 -
Gasket
Always replace
3 -
Nut Always replace30 Nm (22 ft lb)
4 -
Gasket Always replace
5 -
Turbocharger Removing and installing Page 21
-30
6 -
Three Way Catalytic Converter (TWC)
Protect from damageRemoving and installing Page 26
-21
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26-8


7 -
Heated Oxygen Sensor (HO2S)
50 Nm (37 ft lb)Only grease threads with "G 052 112 A3."
Do NOT allow grease to get into slots on
sensor body Checking Repair Manual, 1.8 Liter 4-Cyl.
5V Turbo Fuel Injection &Ignition, Repair
Group 24 Disconnect Heated Oxygen Sensor
(HO2S) harness connector Page 26
-21

8 -
Nut
Always replace25 Nm (18 ft lb)
9 -
Bolt 25 Nm (18 ft lb)
10 -
Mount
Different versions for manual and automatic
transmissions Manual transmission Page 26
-12
, Fig.
1

Automatic transmission Page 26
-13
,
Fig. 2

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26-19

- Remove engine covers.

- Unbolt crankcase ventilation hose -1- at cylinder head cover and heat
shield.
- Unbolt both oil supply line bolts -2-.
- Remove heat shield -3-.
- Remove bolts -4-.
- Remove seal between turbocharger and exhaust manifold.
- Seal opening in turbocharger using clean cloth.

- Remove all nuts (arrows) from exhaust manifold.
- Remove washers and exhaust manifold.
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26-20

Installing
Installation is the reverse of removal, noting the
following:

- Install in sequential order as follows:


Exhaust manifold to cylinder head

Turbocharger to exhaust manifold

Turbocharger bracket to cylinder block

Tightening torques

Component
Tightening
torques
Turbocharger bracket to
turbocharger (bolt and washer
assembly M8) 40 Nm (30 ft
lb)
Turbocharger bracket to cylinder
block 45 Nm (33 ft
lb)
Turbocharger to exhaust
manifold 35 Nm (26 ft
lb)
Exhaust manifold to cylinder
head 25 Nm (18 ft
lb)
Oil supply line to cylinder head 20 Nm (15 ft
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26-22

- Remove air guide duct between cowl and air
cleaner housing.

- Remove air cleaner housing cover.

- Remove the following lines/harness connectors:
1 - At wastegate bypass regulator valve -N75-
2 - At Evaporative Emissions (EVAP) purge regulator valve -N80-
3 - At power output stage -N122-
4 - At Mass Air Flow (MAF) sensor -G70-
- Pull off hose connections and remove air cleaner housing (arrows).
- Remove Heated Oxygen Sensor (HO2S) from Three Way Catalytic
Converter (TWC).
- Remove bolts between front exhaust pipe and Three Way Catalytic
Converter (TWC).
- Unbolt transmission mount for exhaust system at exhaust system.
- Remove bolts between three Three Way Catalytic Converter (TWC)
and turbocharger.
- Remove Three Way Catalytic Converter (TWC) toward top.
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26-23

Installing
Installation is the reverse of removal, noting the
following:


Only grease threads of oxygen sensor with
"G 052 112 A3." Do NOT allow grease to get
into slots on sensor body.

Align exhaust system free of stress Page 26
-24
.

Tightening torques

Components
Tightening
torques
Front exhaust pipe to three way
catalytic converter 25 Nm (18 ft
lb)
Front exhaust pipe to
transmission mount 25 Nm (18 ft
lb)
Three way catalytic converter to
turbocharger 30 Nm (22 ft
lb)
Heated oxygen sensor to three
way catalytic converter 50 Nm (37 ft
lb)
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26-28

Exhaust system, checking for leaks


- Start engine and run at idle.

- Seal tailpipes with cloths or equivalent for
duration of leak test.

- Listen for leaks at following connections:
cylinder head/exhaust manifold, exhaust
manifold/turbocharger, turbocharger/Three Way
Catalytic Converter (TWC), etc.

- Repair leaks.
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