1999 AUDI A4 AFC Engine Lock Carrier Removing For Service Workshop Manual

15-24

Valve stem oil seals, replacing


Cylinder head installed

- Remove toothed camshaft drive belt page 13
-
11
.

- Remove camshafts and hydraulic lifters.

- Remove spark plugs.

- Rotate crankshaft by hand to set piston of
appropriate cylinder to Bottom Dead Center
(BDC).

- Thread VW 653/3 hose, US 1106 cylinder
leakdown tester or equivalent with seal into
spark plug hole by hand and apply a continuous
pressure of at least 6 bar (87psi).

Note:
Tight valve keepers can be loosened by tapping lightly on lever VW 541/1
with a hammer. - Install compressor tool 2036 and adjust to height of studs.
- Remove valve spring with valve spring tensioner VW 541/1 and thrust
pad VW 541/5 or equivalent.
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- Remove valve springs.
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15-25


- Remove valve stem oil seal with slide hammer 3047 A.
- Install new valve stem oil seal.

Note:
Always use the enclosed plastic sleeve for installation of valve stem oil
seals to protect the seal from being damaged by the valve keeper
grooves. - Fit protective sleeve over valve stem, slide seal carefully onto valve
guide.
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15-26

Cylinder head, resurfacing


Minimum dimension -a- = 132.75 mm (5.226 in.)
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15-27

Intake and exhaust valves, checking and
refacing


Checking

- Inspect visually for scoring on valve stem and
valve seat surfaces. If clear signs of wear are
present replace valves.

Refacing intake valve
Refacing exhaust valves
WARNING! - 45a - max 3.5 mm (0.138 in.)
b - min. 0.5 mm (0.020 in.)
Valves must not be refaced by cutting or grinding. Only lapping is permitted.
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15-28

WARNING!

Worn sodium-filled exhaust valves must not
be scrapped without properly disposing of
the sodium.

The valves must be cut into two parts with a
hacksaw between the center of the valve
stem and the valve head. They must not
come into contact with water when being cut
open.

After cutting the valves:
Throw the valves, not more than ten at a
time, into a bucket filled with water and
STAND BACK. A sudden chemical reaction
occurs as the sodium comes into contact
with the water.
Valves that have been processed in this way
can then be disposed of in the normal waste.
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15-29

Valve guides, checking and replacing


Checking
When repairing engines with low compression
due to leaking valves, it is not sufficient to reface
or replace the valve seats and valves. It is also
necessary to check the valve guides for wear.
This is particularly important when checking
engines with high mileage.

- Insert new valve into guide until end of valve
stem is flush with end of guide.

CAUTION!

Due to the difference in valve stem diameters,
make sure that only an intake valve is used to
check intake valve guides, and that only an
exhaust valve is used to check the exhaust
valve guides.

Wear limit - Determine valve rock-amount that valve can move side-to-side.
Intake valve guide 1.0 mm (0.039 in.)Exhaust valve guide 1.3 mm (0.051 in.)
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15-30

Replacing

CAUTION!

Cylinder heads with valve seats that can no
longer be refaced, or which have already
been machined to the minimum dimension,
should no longer be repaired.

CAUTION!
When the shoulder on the new guide makes contact, the pressing
force must not exceed 1.0 ton or the guide shoulder could break off. - Press out worn valve guides from camshaft side using drift 10-206.
(Replacement guides with shoulder must be pressed out from
combustion chamber side.)
- Coat new guides with oil and, using drift 3121, press into cold cylinder
head from camshaft side until shoulder makes contact.
- Use 7mm reamer 3120 to ream new valve guides to size, using plenty
of cutting fluid.
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