AUDI A4 1999 B5 / 1.G APB Engine Valve Gear Service Owners Manual

15-90

Valve stem seals, replacing


Cylinder head installed

- Remove ribbed belt Page 13
-1 .

- Remove toothed belt Page 13
-4 .

- Remove camshafts Page 15
-75
.

- Remove lifters and put them down with the
contact surface downwards. Ensure that lifters
are not interchanged.

- Remove spark plugs.

- Set piston of relevant cylinder to bottom dead
center (BDC).

Note:
Tight cotters can be released by tapping lightly
on the valve lever with a hammer.
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15-91

Exhaust side

Note:
Before attaching the valve assembly appliance,
remove the two studs in the center of the cylinder
head and the three upper studs (inlet side) for
securing the cylinder head cover.

- Screw pressure hose VW 653/3 with sealing ring
finger-tight into spark plug thread of relevant
cylinder, and maintain a constant pressure of at
least 6 bar.

- Attach valve assembly appliance 2036 as illustrated: use M6 x 40 bolts
with large washers.
- Remove valve spring using valve lever VW 541/1 and thrust piece VW
541/5.
- Take out valve spring and valve spring plate.
- Pull off valve stem seal with 3047 A.
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15-92


Inlet side
Note:
The inlet valves are installed in the cylinder head at different angles. - To prevent damage to the new valve stem seals, place plastic sleeve -
A- on the valve stem.
- Lightly oil sealing lip.
- Insert valve stem seal -B- (without oiling outside of seal) into installing
tool 3129 and carefully push it down onto the valve guide.
- When installing new valves, lightly oil valve stems before installing.

Valve spring compressor 3362 can be set accordingly to two different
positions:
1 - Upper position for center valve
2 - Lower position for the two outer valves
3 - Threads on each side to take M6 x 25 bolts for securing spring
compressor to cylinder head
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15-93


- Mount spring compressor 3362 on cylinder head with two bolts
supplied, as in illustration.
- Screw pressure hose VW 653/3 with sealing ring finger-tight into spark
plug thread of relevant cylinder, and maintain a constant pressure of at
least 6 bar.
- Set position of spring compressor for relevant valve, and remove valve
spring using threaded spindle.

- Pull off valve stem seal using 3364.
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15-94


Reworking valves
Valves must not be reworked. Only grinding-in (lapping) is permitted.
WARNING!
Note precautions required when disposing of sodium-cooled
exhaust valves Page 15
-87
. - To prevent damage to new valve stem seals, place plastic sleeve -A-
on valve stem.
- Lightly lubricate sealing lip with oil.
- Insert valve stem seal -B- (without oiling outside of seal) into installing
tool 3365 and carefully push it down onto valve guide.
- When installing new valves, lightly oil valve stems before installing.
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15-95

Valve guides, checking

When repairing engines or cylinder heads with
leaking valves, it is not sufficient to reface the
valve seats and replace the valves. The valve
guides must also be checked for wear. This is
particularly important on high-mileage engines.

Wear limit
If the wear limit is exceeded, replace cylinder head. - Insert valve into valve guide so that end of valve stem is flush with end
of guide. The valve stems have different diameters, so only use an inlet
valve in an inlet guide and an exhaust valve in an exhaust guide.
- Measure amount of rock. Inlet valve guide
Exhaust valve guide
0.8 mm 0.8 mm
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15-96

Valve seats, reworking (refacing)


Notes:

The valve seats should only be reworked just
enough to produce a good seating pattern.
Calculate the maximum permissible reworking
dimension before reworking.
If the reworking dimension is exceeded, the
function of the hydraulic lifters can no longer be
guaranteed and the cylinder head should be
replaced.

Calculating maximum permissible reworking
dimension

- Insert valve and press firmly against valve
seat.

Note:
If the valve is to be replaced as part of a repair,
use a new valve for the calculation.

- Measure distance between end of valve stem and top surface of
cylinder head (illustration shows a 4-valve head).
-
Calculate maximum permissible reworking dimension from measured
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distance and minimum dimension.
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15-97

Minimum dimensions
Outer inlet
valve Center inlet
valve Exhaust
valve
32.2 mm 33.2 mm 33.0 mm
Measured distance minus minimum dimension =
maximum permissible reworking dimension.

Example
Center inlet valve
Measured distance 33.0 mm
Minimum dimension - 32.2
mm
Maximum permissible reworking
dimension = 0.8 mm

Note:
If the measured distance is less than the
minimum dimension, repeat the measurement
with new valves, or replace cylinder head.
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