105643-0150 ZEXEL 9 420 616 846 BOSCH AUTOM. ADVANCE MECHANISM 9420616846 1056430150 1157403810

start by: a) remove cylinder head1. Remove precombustion chambers and valve lifters. 2. Use tooling (A) to compress the valve spring. Remove locks that hold spring to valve stem.3. Remove tooling (A), the valve and spring assembly. 4. Inspect the valve seat insert. Measure the diameter of the valve stem. The minimum diameter of the stem is .3689 in. (9.37 mm). For 2M6402 and 2M6403 valves minimum diameter of valve stem is .3692 in. (9.378 mm). 5. Use tool (B) to measure valve spring force. Test force for valve springs is 55.0 3.5 lb. (244.65 15.57 N).6. The free length of spring is 2.31 in. (58.7 mm). The test length is 1.95 in. (49.5 mm). 7. Put clean engine oil on the valve stem. Install the washer, spring (1) and rotocoil (2). Install the valve through the valve guide.8. Install tooling (A) to put the valve spring under compression.
The valve spring must be put under compression just enough to permit the locks to be put in position on the valve stem.
9. Install the locks on the valve stem.
The locks can be thrown from the valve when the compressor is removed. Make certain the locks are in position before the valve compressor is removed.
10. Remove tooling (A) and hit the valve with a soft hammer to be sure that the locks make a seat on the valve stem.11. Install the valve lifters and precombustion chambers.end by: a) install cylinder head