REMOVAL & INSTALLATION
See Figures 1, 2, 3 and 4
It is understood that the cylinder head has been removed before performing valve removal. On all engines the camshafts must be removed. The rocker shafts and rocker arms must be removed on M20 and M30 engine.
- The factory bmw valve spring compressor and removal tool mounts the cylinder head on a support tray with projections that fit into the combustion chamber. This supports the valves as the springs are compressed and the retainers removed. The bmw tool number for the spring compressor is 11 1 060. There is a different number for the support tray for each engine. Consult with your dealer if you wish to use the factory tools.
- If an aftermarket tool is used, safely and securely support the head while placing the valve spring compressor. Compress the spring.
- Remove the valve spring retainers and carefully release the tension on the spring. Use a magnet to retrieve hard to pick up retainers.
- Remove the spring and upper retainer. Remove the valve from the combustion chamber side of the head.
- Remove the valve stem seal with a removal pliers or equivalent. Remove the lower spring washer or retainer.
- Lubricate the valve guide and stem. Place the valve in the valve guide. Put the lower retainer into place. Wrap the end of the valve stem with thin tape or use bmw tool 11 1 340 (M30), 11 1 350 (M20), 11 1 360 (S14 and S38), 11 1 380 (M42 and M50) to protect the valve stem seal as it is slid over the retainer grooves in the valve stem.
- Press the new valve stem seal into place with tool 11 1 200 or equivalent. The tool fits over the valve stem and provides even pressure to the seal as it is pressed down.
- Install the valve springs. If the valve springs are replaced, the inner and outer springs are replaced as a set. Do not mix new and used inner and outer springs. The color codes must match.
- Place the upper retainer on the springs and compress with the valve spring compressor. Place the retainer locks into the grooves. Release the compressor slowly to make sure the retainers are in place.
Inspect the valve faces and seats (in the cylinder head) for pits, burned spots and other evidence of poor seating. If the valve face or seat is in such bad shape that the head of the valve must be ground in order to true up the face, discard the valve because the sharp edge will run too hot. Check the edge thickness of the valve. Valve wear will cause this thickness to reduce. It is recommended that any reaming or resurfacing (grinding) be performed by a reputable machine shop.
Check the valve stem for scoring and/or burned spots. Check the stem lock retainer grooves for wear. Check the end of the stem for wear. If not noticeably scored or damaged, clean the valve stem with a suitable solvent to remove all gum and varnish. Clean the valve guides using a suitable solvent
Check the valve for signs of bending or piston contact. If a valve has contacted a piston, there will be a telltale mark on the piston crown if the engine is still operational. If there has been piston contact, it is a good bet that the valve is bent. Replace the valve and guide.
Clean the valve face and valve seat in the head. Invert the head and place the valves into the guides. Fill the combustion chamber with gasoline and check for leakage into the ports. If leakage exists, the valve seat and valve face should be refaced to ensure seating chart of valve edge thickness will be included in rebuilding chart.
If the valves need to be refaced, replacing the valves is the best bet. If the valves are to be refaced, refer the job to a reputable machine shop. The valves and the valve seats should be machined at the same time so the proper relationship of the seats can be maintained.
If after refacing the seats leak gasoline as tested above, lap the valves.
- Clean the valve face and seat. Lubricate the valve stem and insert in the head.
- Place a fine lapping compound on the valve seat and place the lapping tool on the valve head. The lapping tool is a stick with a suction cup to attach to the valve. The valve is rotated with the stick.
- Rotate the valve back and forth, lifting the valve of its seat every so often.
- Once a fine finish is achieved, remove the valve and clean all traces of lapping compound off. Clean the cylinder head of all traces of lapping compound. Check for leakage.
All compound must be cleaned and removed as the lapping compound is extremely abrasive and will quickly wear any moving parts it contacts.