engine AUDI A8 1996 D2 / 1.G AHA ATQ Engines Valve Gear Service Manual

15-1


Valve gear, servicing

WARNING!

Do not re-use any fasteners that are worn or
deformed in normal use.
Some fasteners are designed to be used only
once, and are unreliable and may fail if used
a second time. This includes, but is not
limited to, nuts, bolts, washers, circlips and
cotter pins. Always follow the
recommendations in this manual-replace
these fasteners with new parts where
indicated, and any other time it is deemed
necessary by inspection.

CAUTION!

After installing new hydraulic valve lifters the
engine must not be started for about 30
minutes (otherwise the valves will strike the
pistons). Turn the crankshaft two complete
revolutions by hand before starting.
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15-14

Cylinder head oil seals, replacing


Oil seal for camshaft drive (left and right
cylinder heads)

- Rotate engine to Top Dead Center (TDC).

- Remove toothed belt page 13
-12
.

- Remove rear toothed belt guard.

Note:
Do not apply oil to sealing lip or outer circumference of seal. - Remove seal using 3240 seal extractor.
- Clean contact surface and sealing surface.
- Install 3241/2 pull sleeve from 3241/1 press sleeve onto camshaft.

- Press seal flush into cylinder head using 3241/1 press sleeve and
3241/3 bolt.
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15-16


Rear sealing flange (left cylinder head)
The sealing flange and rear oil seal on the left cylinder head must be
replaced together as follows: - Press seal flush using 3241/1 press sleeve and 3241/3 bolt.
- Unbolt engine coolant expansion tank from bracket.
- Remove crankshaft ventilation line from cylinder head cover.
- Unbolt Camshaft Position (CMP) sensor.
Tightening torque: 10 Nm (7 ft lb)
- Unbolt shutter wheel for Camshaft Position (CMP) sensor G40 and
carefully pry out using screwdriver.
- Remove cylinder head cover.

- Remove double bearing cap (arrows).
- Remove seal and sealing flange.
- Clean running and sealing surfaces as well as contact surface of
double bearing cap.
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15-18

Cylinder head, removing and installing


Note:
The following instructions apply to the left
cylinder head.

Removing

Lock carrier in service position page 13
-
1 .

- Remove ribbed belt page 13
-8 .

- Remove toothed belt page 13
-12
.

- Remove engine cover (arrows).

- Remove noise insulation panel (arrows).
- Unbolt left and right-side front exhaust pipes from exhaust manifold.
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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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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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15-24

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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15-29

Compression, checking


Test conditions

Engine oil temperature at least 30 C

Battery fully charged

- Disconnect harness connectors from all 6 fuel
injectors.

- Disconnect 5-pin harness connector from power
output stage of ignition coils.

- Open throttle fully.

- Use VAG1381 or VAG1763 compression tester
to check compression.

- Operate starter until no further pressure
increases are indicated by VAG1381 or
VAG1763 compression tester.

Compression pressure
New
Wear
limit Max. permissable
difference between
cylinders
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15-30

Sealing cap (core plug) in cylinder head,
installing

Cylinder heads supplied as replacement parts
can be used on either the left or right-sides of the
engine. A sealing cap (core plug) must be
installed in the front end of the cylinder head in
each case.

- Coat outside circumference of sealing cap (core
plug) with sealant AMV 188 001 02.

CAUTION!

Part numbers are listed here for reference
only. Always check with your Parts
department for the latest information.

- Using VW295 needle bearing drift, drive in sealing cap (core plug) until
outside rim is flush with end of chamfer in cylinder head (see inset).
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