engine AUDI A6 1995 C5 / 2.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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15-42

Oil seals for camshafts, replacing


Cylinder head installed
Lock carrier in service position Page 13
-1

Special tools and equipment

2085 seal puller
3241 seal installer
3036 retainer

Replacing exhaust camshaft oil seal

Removing

- Remove ribbed belt and ribbed belt tensioner
Page 13
-15
.

- Remove engine covers.

- Remove upper toothed belt cover Page 13
-
29
.

-
Turn crankshaft at central bolt of toothed belt gear in direction of
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engine rotation to TDC Cyl. 1 marking (arrows).
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15-50

Camshafts and hydraulic chain
tensioner, removing and installing


Cylinder head installed
Lock carrier in service position Page 13
-1

Special tools and equipment

3036 retainer
3366 bracket-tensioner

Removing

- Remove ribbed belt and ribbed belt tensioner
Page 13
-15
.

- Remove engine covers.

- Remove upper toothed belt cover Page 13
-
29
.

- Turn crankshaft at central bolt of toothed belt gear in direction of engine
rotation to TDC Cyl. 1 marking (arrows).
- Remove cylinder head cover Page 15
-17
.
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15-58


Note:
When turning camshaft, crankshaft must not be at TDC Cyl. 1 for any
cylinder. Valves and/or pistons may be damaged.
Note:
Follow all procedures for removing and installing toothed belt Page 13
-
29
.
CAUTION!
Note:
When installing ribbed belt, make sure it is seated correctly on the pulleys. - Align marking on camshaft gear with marking on cylinder head cover.
- Align marking on vibration damper with marking on lower toothed belt
cover.
- Install toothed belt (adjust valve timing) Page 13
-32
.
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.
- Install ribbed belt and ribbed belt tensioner Page 13
-15
.
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15-60

Hydraulic valve lifters, checking


Special tools and equipment

Feeler gauge
Wood or plastic wedge

Note:
Hydraulic valve lifters cannot be serviced.
Irregular valve noise when starting engine is
normal.

- Start engine and let run until coolant
temperature reaches at least 80 C (176 F).

- Increase RPM to 2500 for about 2 minutes; if
necessary test drive vehicle.

Note:
If irregular valve noises disappear but then
reappear during drive, replace oil retaining valve.
Oil retaining valve is located in oil filter bracket
Page 17
-6 .
If hydraulic valve lifters are still loud, locate faulty
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15-61

Vehicles with manual transmission

- Switch ignition off, shift into fourth gear and push
vehicle forward.

Vehicles with automatic transmission

- Remove noise insulation panel and turn central
bolt of toothed belt gear for crankshaft in
clockwise direction.

- Determine play between cams and valve
lifters.

CAUTION! - Push down on valve lifters using wood or plastic wedge. If 0.20 mm
(0.008 in.) feeler gauge can be inserted between camshaft and valve
lifter, replace valve lifter.
Valve lifter, replacing Page 15
-50
.
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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15-65

Installing

CAUTION! - Place plastic sleeve -A- on valve stem to prevent damage to new valve
stem oil seals.
- Lightly oil lip of valve stem oil seal -B-.
- Insert valve stem oil seal into 3365 valve stem seal fitting tool and
carefully slide onto valve guide.
- Remove plastic sleeve.
- Install camshafts Page 15
-53
.
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.
Pa
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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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