Valve Seat: Service and Repair

Component Notes And Information

NOTE:
^ During service procedures, refer to the illustration above and the information below.
^ Cylinder heads which have cracks between the valve seats or between valve seat inserts and the spark plug thread can continue to be used without reducing service life, provided the cracks do not exceed a maximum width of 0.50 mm.

1 Bearing Cap
- Installed position, refer to Fig. 2 below
- Installation sequence, refer to replacement. Service and Repair
2 Cam Bearing Cap Nut
- Tighten to: 20 Nm (15 ft lb)
3 Camshafts
- Axial clearance checking, refer to Fig. 1 below
- Removing and installing, refer to replacement. Service and Repair
- Checking radial clearance with Plastigage:
Wear limit: 0.10 mm
Run-out: max. 0.01 mm
- Identification and valve timing, refer to Fig. 4 below
4 Camshaft Sprocket
- Removing and installing, refer to replacement. Service and Repair
5 Sensor wheel
- For Camshaft Position sensor
- When installing, contact surfaces on timing chain and sensor wheel must be dry
- Removing and installing. refer to replacement. Service and Repair
6 Camshaft Sprocket Bolt
- Tighten to: 100 Nm (74 ft lb)
- To remove and install: counter-hold with 24 mm open end wrench on camshaft refer to replacement. Service and Repair
- Oil bulkhead contact surface when installing
7 Cylinder head deck height
- Minimum: a = 139.5 mm
8 Cylinder Head
- See NOTE: at top of article
- Re-working valve seats refer to procedures below
9 Valves
- Do not rework, only lapping-in is permitted
- Valve dimensions, refer to Fig. 3 below
10 Valve guide
- Service version with collar
- Checking. Testing and Inspection
- Replacing refer to Replacement. Service and Repair
11 Valve stem seal
- Replacing, refer to Replacement. Service and Repair
12 Valve springs
- Removing and installing:
- Cylinder head removed: use 2037 valve spring compressor
- Cylinder head installed, refer to Replacement. Service and Repair
13 Valve spring plate
14 Valve keepers
15 Hydraulic lifter
- With hydraulic valve clearance compensation
- Do not interchange
- Store with cam contacting surface facing downwards
- Oil contacting surfaces checking. Testing and Inspection
- Before installing; check camshaft axial clearance: refer to Fig. 1 below

Procedures





Fig. 1 Camshaft Axial Clearance, Checking
Special tools, testers and auxiliary items
- VW 387 Universal dial gauge bracket
- Dial gauge

Test sequence
- Wear limit: maximum 0.15 mm
- Perform check with hydraulic lifters removed and with first and last bearing caps installed on the appropriate camshaft





Fig. 2 Camshaft Bearing Caps, Installed Position

NOTE: Bearing cap identification must be readable from the exhaust side of the cylinder head and the arrow pointing to vibration damper end.

Part 1 Of 2:

Fig. 3 Valve Dimensions

Part 2 Of 2:

NOTE: Valves may not be reworked. Only lapping-in is permitted.





Fig. 4 Camshaft Identification Valve Timing
- Item 1 = Camshaft for cylinders 1, 3 and 5
- Item 2 = Camshaft for cylinders 2, 4 and 6

Identification





- Cam base diameter: a = 34 mm
- Identification by numbers and letters stamped on camshaft





Valve timing table (at 1 mm valve lift)

Refinish Valve Seats
Special Tools, Testers And Auxiliary Items
- Depth gauge
- Valve seat refacing tool

NOTE:
^ When repairing engines with leaking valves, it is not always sufficient to rework or replace valve seats and valves. It is also necessary to check the valve guides for wear This is particularly important on high mileage engines.
^ The valve seats should only be reworked the minimum amount to achieve a perfect seating pattern. The maximum permissible reworking dimension must be calculated before starting 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.

Maximum Permissible Reworking Dimension, Calculating
- Insert valve and press firmly against seat

NOTE: If a valve will be replaced as part of the repair use the new valve for the calculation.






- Measure distance -a- between end of valve stem and upper edge of cylinder head
- Calculate max. permissible reworking dimension from the measured distance -a- and the minimum dimension
- Minimum dimension:
Intake valve: 33.9 mm
Exhaust valve: 34.1 mm
- Measured distance minus minimum dimension = maximum permissible reworking dimension

Example:

Measured distance -a- 34.80 mm
Minus
Minimum dimension 34.10 mm ______________________________________
Equals
Maximum permissible
reworking dimension 0.70 mm





Intake Valve Seat, Re-Working
a = 38.30mm
b = Max. permissible reworking dimension
c = 1.40 mm to 2.00 mm
if necessary rework valve seat insert using 75° correction reamer
Z = Cylinder head lower edge
ax = 45° valve seat angle
B = 30° upper correction angle
Y = 75° lower correction angle





Exhaust Valve Seat, Re-Working
a = 33.50 mm
b = Max. permissible reworking dimension
c = 2.00 mm to 2.50 mm
if necessary rework valve seat insert using 75° correction reamer
Z = Cylinder head lower edge
ax = 45° valve seat angle
B = 30° upper correction angle