Valve Gear, Servicing
Valve gear, servicing
Note:
^ Cylinder heads which have cracks between the valve seats or between valve seat inserts and the spark plug thread can be used further without reducing service life, provided the cracks do not exceed a maximum of 0.3 mm in width, or when no more than the first four spark plug threads are cracked.
^ After installing new hydraulic lifters, the engine must not be started for approximately 30 minutes (otherwise valves will strike pistons), then turn crankshaft two rotations.
1. 10 Nm
2. Intake camshaft
^ Checking axial clearance, Refer to Fig. 2
Checking radial clearance with plastigage:
^ Wear limit: 0.1 mm
^ Run-out: max. 0.01 mm
3. Drive chain
^ Before removing mark direction of rotation (installation position), Refer to Camshaft, Engine, Service and Repair, Camshaft, removing and installing
4. 10 Nm
5. O-ring
^ Always replace
^ Only for engine codes: AWP, AWV
6. Camshaft adjustment valve (N205)
^ Only for engine codes: AWP, AWV
^ Check camshaft adjustment, Refer to Camshaft, Engine, Adjustments
7. 3 Nm
^ Only for engine codes: AWP, AWV
8. Camshaft adjuster
^ Only for engine codes: AWP, AWV
^ For vehicles with engine code: APH; Chain tensioner
^ Secure with 3366 before removing, Refer to Camshaft, Engine, Service and Repair, Camshaft, removing and installing
^ Seal transition of hydraulic chain tensioner/cylinder head, Refer to Valve Intake/Exhaust, Service and Repair, Valve Gear, Servicing
^ Check camshaft adjustment, Refer to Camshaft, Engine, Adjustments,
9. Gasket
^ Rubber/metal seal
^ Replace
10. Cylinder head
^ Removing and installing, Refer to Cylinder Head, Service and Repair, Cylinder head, removing and installing
^ Refacing valve seats, Refer to Valve Seat, Service and Repair
^ Reworking sealing surface
^ Sealing transition points, Refer to Fig .4 and
11. Valves
^ Do not rework only grinding-in is permitted
^ Valve dimensions, Refer to Fig .3
^ Sodium-filled exhaust valves: Observe disposal instructions, Refer to Note under Fig. 3. Valve dimensions
12. Oil seal
^ Replacing, Refer to Seals and Gaskets, Engine, Camshaft Oil Seal, Service and Repair
13. Hood
^ For Camshaft Position (CMP) sensor
^ When installing note fixing arrangement
14. Washer
^ Conical
15. 25 Nm
16. Camshaft Position (CMP) sensor -G40
17. 10 Nm
18. 65 Nm
^ Use counter-hold 3036 to loosen and tighten
19. Camshaft sprocket
^ Note installation position: small web of camshaft sprocket points outward and No. 1 Cyl. TDC marking is visible
^ Note position when installing toothed belt, Refer to Timing Belt, Service and Repair
20. Oil seal
^ Replacing, Refer to Seals and Gaskets, Engine, Camshaft Oil Seal, Service and Repair
21. Valve guide
^ Checking, Refer to Valve Guide, Testing and Inspection
22. Valve stem seal
^ Replacing, Refer to Seals and Gaskets, Engine, Valve Guide Seal, Service and Repair
23. Valve spring
^ Removing and installing: remove cylinder head with 3362
^ Installing, Refer to Seals and Gaskets, Engine, Valve Guide Seal, Service and Repair
24. Upper valve spring plate
25. Valve keepers
26. Hydraulic lifter
^ Do not interchange
^ With hydraulic valve clearance compensation
^ Checking, Refer to Lifter Valve, Testing and Inspection
^ Store with cam contact surface downward
^ Before installing check camshaft axial clearance
^ Oil contact surface
27. Intake camshaft bearing cap
^ Installation position and installation sequence, Refer to Camshaft, Engine, Service and Repair, Camshaft, removing and installing
28. Double bearing cap
^ Lightly coat bearing cap contact surface with sealant AMV 174 004 01
^ Must sit on alignment bushing
^ Seal transitions of double-bearing cap/cylinder head, Refer to Fig. 4.
29. Exhaust camshaft bearing cap
^ Installation position and installation sequence,
30. Exhaust camshaft
^ Checking axial clearance
^ Removing and installing, Refer to Camshaft Engine, Service and Repair
Checking radial clearance with plastigage:
^ Wear limit: 0.1 mm
^ Run-out: max: 0.01 mm
Fig. 1 Reworking cylinder head sealing surface
The dimension for reworking is measured through the holes for the cylinder head bolts.
-a- = minimum 139.2 mm
Fig. 2 Checking camshaft axial clearance
Special tools and equipment
^ Universal dial indicator bracket VW387
^ Dial indicator
Check with hydraulic lifters and chain removed and No. 2 and 4 bearing caps installed.
Wear limit: max. 0.2 mm
Fig. 3 Valve dimensions
Note: Valves must not be reworked. Only lapping-in is permitted.
Note: Care must be taken when disposing of old sodium filled valves. They must be cut through in the center of the stem with a hacksaw. When doing this they must be perfectly dry. The valves prepared in this way can then be thrown into a bucket of water a maximum of ten at a time. When doing this step back quickly because a sudden chemical reaction causes the sodium filling to burn. After this treatment, the valves can be put in with the normal scrap.
Fig. 4 Sealing transition points between double bearing cap and cylinder head
- Carefully apply a thin coat of sealant D 454 300 A2 to both edges of sealing surfaces between double bearing cap and cylinder head -arrows- using a small screwdriver.
Fig. 5 Sealing transition points between chain tensioner/cylinder head
- Carefully apply a thin coat of sealant "D 454 300 A2" to both edges of sealing surfaces between camshaft adjuster and cylinder head -arrows using a small screwdriver.