AUDI A6 1999 C5 / 2.G AHA ATQ Engines Valve Gear Owner's Manual

- Unbolt exhaust system from transmission bracket.
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15-19

- Place VAG1306 drip tray beneath engine.

- Open engine coolant expansion tank cap.

WARNING!

The cooling system is pressurized when the
engine is warm. When opening the expansion
tank, wear gloves and other appropriate
protection, cover the cap with a cloth and
open carefully to relieve system pressure
slowly.

- With bumper removed, open coolant drain plug (arrow) on lower left of
radiator by turning it counterclockwise. If necessary, attach accessory
hose to connection.
- With bumper installed, pull off retaining clamp for lower right radiator
hose (from radiator to engine) and disconnect radiator hose from
radiator.

- Using 3247 hex ball socket, open coolant drain plug on engine (arrow)
as well.
- Unbolt engine coolant expansion tank from bracket and lay aside
(remove if necessary).
-
Disconnect crankshaft housing ventilation line from cylinder head
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cover.
- Remove intake air duct between Mass Air Flow (MAF) sensor and
intake air elbow.
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15-20


- Disconnect blue harness connector on Intake Manifold Tuning (IMT)
valve.
- Disconnect black harness connector for intake air temperature sensor
on resonator.
- Cut tie wraps and move wiring to side.
- Disconnect vacuum line at cruise control vacuum diaphragm and at
vacuum booster.
- Unbolt cruise control vacuum diaphragm and unhook cruise control
vacuum diaphragm linkage at throttle body.
- Disconnect harness connector on throttle body and vacuum lines on
fuel pressure regulator.

- Disconnect harness connectors from camshaft adjustment valve and
from fuel injectors (arrows).
- Disconnect harness connectors from Engine Coolant Temperature
(ECT) sensor and Camshaft Position (CMP) sensor (arrows).
- Cut tie wraps on valve cover.
- Unclip wiring retainer on fuel rail and disconnect crankshaft housing
ventilation lines from left and right-side valve covers. Move hoses and
wiring clear (to rear).
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15-21


- Disconnect harness connector for tank diagnostic system in engine
compartment at arrow.
- Remove 4 bolts for fuel rail on intake manifold.
- Unclip fuel supply and return lines from retainer.
- Move fuel rail together with fuel injectors aside. Cover fuel injectors
with clean cloth.
- Install 3391 camshaft locator bar onto camshaft locking plates.
- Loosen both bolts for camshafts and back out bolts approx. 5 turns.
- Remove 3391 camshaft locator bar.

- Remove camshaft gear using T40001 special tool.
- Disconnect left-side spark plug connectors.
- Unbolt bracket for ignition coils (4 bolts) and move to right side together
with ignition coils.
- Unhook accelerator pedal cable and pull up out of retaining bracket.
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15-22


- Disconnect vacuum line at throttle body and line between vacuum
booster and intake air elbow (arrows).
- Remove intake air elbow.
- Remove intake manifold.
- Disconnect heated oxygen sensor harness connector at left-side of
heater core and set aside.

- Remove left-rear toothed belt guard (arrows).
- Unbolt coolant hose at rear of cylinder head.
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15-23


- Unbolt coolant hose at front of cylinder head (arrows).
- Using 3452 polydrive special tool, loosen cylinder head bolts in reverse
order of tightening sequence and remove.
- Carefully lift off cylinder head.

- When removing and installing, use 3452 polydrive together with
normal commercial 10 mm socket.
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15-24

Installing

Notes:

Bolt holes in engine block for cylinder head
bolts must be free of oil and coolant.
Always replace cylinder head bolts.
Vacuum line connections page 10-23
When installing a new cylinder head:

- Install centering pin for intake manifold.

- Replacement cylinder head may be used to
replace left or right cylinder head. Install sealing
cap at appropriate front end of replacement
cylinder head.

- Coat lip of sealing cap with sealant AMV 188
001 02.

- Using VW295 needle bearing drift press in sealing cap until lip of cap
seals with chamfer end of cylinder head.
- Before installing cylinder head, set crankshaft and camshafts to TDC
for cylinder 3.
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- Install cylinder head gasket onto guide sleeves. Marking "oben" or Part
No. must face toward cylinder head.
- Install cylinder head, install cylinder head bolts and tighten hand-tight.
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15-25


It is not necessary to re-torque cylinder head bolts again after repairs
have been completed. - Tighten cylinder head bolts in two stages in sequence shown, as
follows:
Stage 1: 60 Nm (44 ft lb) Stage 2: additional 1/2 turn (180 ) using rigid wrench (in two 1/4 turns
(90 ) if necessary).

Sealing contact surfaces between bearing cap and cylinder head.
- Carefully apply small amount of sealant D 454 300 A2 at four end
points of sealing surfaces on cylinder head using small screwdriver.
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