Examining Contact Surface of Cylinder Head

NOTE: Numbers and letters in parentheses ( ) indicate a component or tool in the associated illustration.

1. Remove valves
2. Inspect flatness of cylinder head in longitudinal direction
- Measure height of cylinder head (inspection dimension "H") and note
3. Reface contact surface of cylinder head if required noting the following:
- Face contact surface of cylinder head only if porous or damaged points exist or if there is an impermissible difference of the flatness in the longitudinal direction.
- The stock removal at the cylinder head and at the crankcase of an engine-must together not be more than 0.4 mm.
- If cracks are suspected (internal loss of coolant), pressure test cylinder head.

CAUTION: The upper contact surface of the cylinder head must not be machined otherwise the basic bores of the camshaft bearings will be altered.

4. Once again measure height of cylinder head (inspection dimension "H")
- Measure stock removal
- Specifications:
Overall height ""H"": 135.90 - 136.00 mm
Minimum Height: 135.5 mm
Permissible difference in flatness:
Longitudinal: 0.08 mm
Transverse: 0.00 mm
Permissible surface finish:
Peak to valley height: 3/10 pm
5. Insert valves (42, 43)
6. Measure inspection dimension (T) between end of valve stem and base of camshaft bearing and note.
- Insert a 6 mm diameter bar into the middle of the camshaft bearing base and measure dimension T with caliper gage.
- If measurement obtained is less than dimension T, no further correct valve clearance compensation exists; replace valve seat ring or cylinder head as necessary.
- Specifications:
With standard size camshaft diameter
Inlet: 25.18 - 25.70 mm
Exhaust: 23.18 - 23.70 mm
With repair size camshaft diameter:
Inlet: 24.93 - 25.45 mm
Exhaust: 22.93 - 23.45 mm
7. Rework valve seats according to stock removal at cylinder head
8. Install in the reverse order