seats AUDI A3 1998 8L / 1.G AEB ATW Engines Valvetrain Servicing Workshop Manual

15-32


Valvetrain, servicing

Note:

Cylinder heads with small cracks between the
valve seats that are less than 0.3 mm (0.012
in.) wide and/or between one valve seat and
only the first 4 threads of the spark plug thread,
can continue to be used without reduced
service life.
Always replace gaskets, seals and O-rings.

CAUTION!
After installing the camshafts, the engine
must not be started for approx. 30 minutes.
The hydraulic valve lifters have to settle
(otherwise valves will strike the pistons).
After installing the valvetrain and lifters,
carefully rotate the crankshaft by hand at
least 2 full revolutions before starting to be
sure that valves do not strike the pistons.
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1 -
Bolt
65 Nm (48 ft lb)Use 3036 retainer when loosening or
tightening
2 -
Camshaft gear For exhaust camshaftVerify correct installation position: thin rib
of camshaft gear points forward and TDC
Cyl. 1 marking is visible from front Page 15
-45

3 -
Oil seal
For exhaust camshaftAlways replace Page 15
-42
4 -
Cylinder head
Note Page 15
-32
Check valve guides, reface valve seats
Page 15
-66

Bearing cap bushings must be installed in
cylinder head Seal contact surfaces Page 15
-9 , Fig.
3
and Fig. 4

Reface valve seats Page 15
-71
5 -
Valve guide
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15-37


19 -
Hydraulic chain tensioner
Before removing, secure with VAG3366
chain tensioner bracket Removing and installing Page 15
-50
Seal contact surfaces between hydraulic
chain tensioner and cylinder head Page 15
-9 , Fig. 4

20 -
Rubber/metal seal
Replacing Page 15
-53
21 -
Gasket
Always replace
22 -
Exhaust valve Sodium-filledFollow disposal procedures for sodium-
filled valves Page 15
-40

Do not reface by grinding, only hand
lapping is permitted Valve dimensions Page 15
-39
, Fig. 1
Checking valve guides Page 15
-66
Refacing valve seats Page 15
-71Pa
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15-38


23 -
Intake valve
Do not reface by grinding; only hand
lapping is allowed Valve dimensions Page 15
-39
, Fig. 1
Checking valve guides Page 15
-66
Refacing valve seats Page 15
-71
24 -
Oil seal
For intake camshaftReplacing Page 15
-42
25 -
Shutter wheel for Camshaft Position
(CMP) sensor -G40-
Note position: insert lug in camshaft notch
26 -
Washer ConicalNote position
27 -
Bolt 25 Nm (18 ft lb)
28 -
Camshaft Position (CMP) sensor -G40-
housing
29 -
Bolt 10 Nm (7 ft lb)
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15-67

Valve guides, replacing


Special tools and equipment

VW411 punch
3120 reamer (7mm) and cutting fluid
3360 driver
3361 press-in pad

Removing

- Clean cylinder head and check.

Note:
Cylinder heads with valve seats that cannot be
refaced or cylinder heads that have been
resurfaced to the minimum dimension are not
suited for valve guide replacement.
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15-69

Installing

- Using 3360 driver, press new, oiled valve guides
from camshaft side to collar into cold cylinder
head.

Note:
After valve guide with collar is seated, insertion
pressure may not exceed 10kN (2248 lbs =
approx 1.0t), as collar may break off.

- Using 3363 reamer -7 mm, ream valve guide.
Use cutting fluid.

- Reface valve seats Page 15
-71
.

- Replace valve stem oil seals Page 15
-62
.
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15-71

Valve seats, refacing


Note:
If a perfect contact pattern isn't obtained after
hand lapping valves, reface valve seats.

Special tools and equipment

Depth gauge
Valve seat refacing tool

Note:
When servicing engines with low compression
due to leaking valves, it is not sufficient to
reface or replace the valve seats and valves. It
is especially important to check valve guides for
signs of wear on high-mileage engines Page 15
-66
.

Only reface valve seats enough until a perfect
contact pattern is obtained.
Before refacing, determine maximum refacing
dimension.
If refaced dimension is exceeded, hydraulic
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15-74


Valve seats, refacing Intake valve seat
Diameter -a- = 26.2 mm (1.031 in.)
Dimension -b- = 1.5-1.8 mm (0.059-0.070 in.)
Z = Cylinder head lower edge
Angle -a- =
45 valve seat angle Angle -b- =
30 upper correction angle Angle -g- =
60 lower correction angle Exhaust valve seat
Diameter -a- = 29.0 mm (1.142 in.)
Dimension -b- = approx. 1.8 mm (0.070 in.)
Z = Cylinder head lower edge
Angle -a- =
45 valve seat angle Angle -b- =
30 upper correction angle Angle -g- =
60 lower correction angle
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