Different valve gears — AUDI

Since approx. 09.94 (as of engine no. ABK 245 263) "light valve gear" has been fitted instead of "old valve gear".

Main distinguishing features of "light valve gear":

Discontinuation of camshaft bearing
Discontinuation of inner valve spring
Discontinuation of lower valve plate
Smaller valve stem diameter
Smaller ID of valve guides

Notes:

Cylinder heads with cracks between valve seats or between one valve seat ring and spark plug thread can be re-used without shortening service life if cracks are only minor (max. 0.3 mm wide) or if only the first 4 turns of the spark plug thread are cracked.
Engine is not to be started for approx. 30 minutes after installing camshaft, so as to allow hydraulic valve lifters to settle (valves would otherwise strike piston).
After working on valve gear, carefully crank engine through at least 2 revolutions to ensure that no valves make contact on starting.
Always replace gaskets and oil seals.
Fig. below shows cylinder head with light valve gear (as of engine no. ABK 245 263).
Distinguishing features of old valve gear (up to engine no. ABK 245 262) => Fig.
15-44
.

Valve
Not to be reworked; only grinding-in permissible
Valve dimensions for old valve gear
=> Fig.
15-45
Valve dimensions for light valve gear => Fig.
15-46

Cylinder head
Heed note => Page
15-37
Checking valve guides => Page
15-65
Reworking valve seats=> Page
15-69

Valve spring
Only one valve spring per valve for light valve gear
Valve springs for old valve gear
=> Fig.
15-44
Removing and installing
With cylinder head fitted=>Page
15-61
With cylinder head removed, use 2037

Valve spring plate
Valve cotters
Hydraulic bucket tappet
Checking => Page
15-59
Removing and installing=>Page
15-61
Not to be interchanged
Set down with bearing surface downwards
Checking axial clearance of camshaft before fitting => Fig.
15-44
Lubricate bearing surface

Camshaft
Checking axial clearance => Fig.
15-44
Removing and installing=>Page
15-53
Check radial clearance with Plastigage
Wear limit: 0.1 mm
Run-out: max. 0.01 mm

Bearing cap
Installation position => Fig.
15-45
Installation sequence => Page
15-53
, Removing and installing camshaft
Before fitting, apply thin layer of "D 454 300 A2" to resting surfaces of bearing cap no. 1
Sealing transitions with "AMV 174 004 01"=>Fig.
15-7

20 Nm
Woodruff key
Check for firm attachment

Oil seal
Replacing => Page
15-47

100 Nm
Use counterhold 3036 when slackening off and tightening

Washer
Camshaft sprocket
Removal and installation involve taking out toothed belt =>Page
13-28
Pay attention to installation position:
Narrow web of camshaft sprocket faces front and no. 1 cyl. TDC mark is visible from front =>Page
15-51
Installation position fixed by Woodruff key -Item
10
-

Valve stem seal
Replacing => Page
15-61

Valve guide
Checking => Page
15-65
Replacing => Page
15-66

Fig. 1
Checking axial clearance of camshaft

Wear limit: max. 0.15 mm

Take measurement with bucket tappets removed and first and last bearing cap fitted.

Fig.2
Old valve gear

(up to engine no. ABK 245 262)

1 -
Lower valve spring plate
2 -
Valve stem seal
3 -
Inner valve spring
4 -
Outer valve spring
5 -
Upper valve spring plate
6 -
Valve cotters
7 -
Hydraulic bucket tappet

Fig. 3
Installation position of camshaft bearing cap

Watch out for centre offset. Before installing camshaft, place bearing cap in position and determine fitting location.

Fig.4
Valve dimensions for old valve gear (up to engine no. ABK 245 262)

Dimension · Inlet valve · Exhaust valve
øa · mm · 39.5 ± 0.15 · 32.9 ± 0.15
øb · mm · 7.97 ± 0.02 · 7.95 ± 0.02
c · mm · 91.9 · 91.2
α · <° · 45 · 45

Fig.5
Valve dimensions for light valve gear (as of engine no. ABK 245 263)

Dimension · Inlet valve · Exhaust valve
øa · mm · 39.5 ± 0.15 · 32.9 ± 0.15
øb · mm · 6.92 ± 0.02 · 6.92 ± 0.02
c · mm · 91.85 · 91.15
α · <° · 45 · 45