S 420 (140.043) V8-4.2L (119.981) (1996)
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Remove bucket tappet (3) of relevant cylinder, install.
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Screw connection hose (4) of cylinder leak tester into spark plug hole.
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Fix crankshaft in position with retaining lock to prevent it rotating. See: Service and Repair/Procedures
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Pressurize compression chamber.
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Insert lever presser (9) with thrust piece (5), special tools 111 589 18 61 00 and 119 589 06 63 00, into slide (7).
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Attach thrust piece (6) to valve spring retainer (15) vertically.
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Fix slide (7) in position with bolt (8).
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Compress valve spring (17).
CAUTION Valves must not touch the piston crown otherwise they will be bent.
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Remove valve collets (14) with tweezers, special tool 116 589 06 63 00, (6) or magnetic finger, install.
Installation Note: Coat valve spring retainer (15) for fixing valve collets (14) with grease.
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Remove valve spring retainer (15) with valve spring (17), install.
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Replace valve stem seal (19). See: Seals and Gaskets/Valve Guide Seal/Service and Repair
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Remove bottom valve spring retainer (20) and examine for scoring, install.
NOTE:
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Valve springs, upper and lower valve spring retainers with scoring must be replaced.
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The valve springs of the inlet and exhaust valves are identical.
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As of 01/1993 conical-shaped valve springs are installed together with modified valve spring retainers and lighter bucket tappets.
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The inner valve spring is no longer fitted.
Conical-Shaped Valve Springs