Valve Spring: Testing and Inspection

Installed length, dimension "A"
1. Assemble shims, valve spring support, valve, auxiliary spring, e.g. for oil thermostat (engine 928), part number 928.107.171.01, valve spring cap and valve keepers.

NOTE: If required, the spring may be shortened slightly to facilitate assembly.





2. Using a depth gauge, measure vertically from valve spring cap top surface to valve spring seat surface. Record measurement.





3. Determine thickness of valve spring cap. Record measurement.
4. Determine actual dimension

Example for determining the actual dimension:
Inlet valve spring
Measured value: 38,5
Thickness of valve spring cap: - 1.6 = 36.9

Result:
The value of 36.9 is within the admissible tolerance.

NOTE: Take care not to confuse the parts after the measurement.

Installation dimension specifications





Engine M64 / 05 / 06 / 07 / 08
Inlet Valve Dimension "A": 36.7 + 0.3 mm
Exhaust Valve Dimension "A": 35.7 + 0.3 mm

Engine M64 / 20 (RS)
Inlet Valve Dimension "A": 37.2 + 0.3 mm
Exhaust valve Dimension "A": 35.8 + 0.3 mm