Valve Spring: Service and Repair

OVERVIEW










REMOVAL AND INSTALLATION





1 Cylinder head removed: attach cylinder head to assembly board 111589 02 59 00 with two cylinder head bolts.





2 Cylinder head installed: hold timing chain (23) at left and right cylinder head with M8x 50 mm bolts (arrow) so that it does not jam when rotated.





3 Cylinder head installed: rotate piston of the cylinder to be processed to TDC position with socket wrench bit.
if rotated at the crankshaft, it is important to ensure that the starting position is restored so that the colored markings made on the timing chain for setting the timing of the camshafts can again be used.





The relevant piston is in the TDC position if the marking numbers on the vibration damper, as shown in the table opposite, are aligned with the TDC pointer.





4 Cylinder head installed: fix crankshaft in position with retaining lock 602 589 00 40 00 to prevent it turning.





5 Cylinder head installed: screw connection hose (4) of the cylinder leak tester into the spark plug hole and pressure compression chamber (approximately 5 bar).





6 Use a suitable retaining fork (15) to screw hinged bearing (19) into thread of camshaft bearing caps and align.
Removing valve springs with 3-groove valve collets or valve springs with 8 mm exhaust valve stem
3-groove valve collets installed as of engine end number
980 016 880 up to 980 026 776
981 000 347 up to 981 005 051





7 Attach depresser (5) with lever handle (3) and thrust piece (7) 111 589 25 63 00 into hinged bearing (19) and align.





8 Compress valve springs and remove valve collets with magnetic finger (06) 116 589 06 63 00.
if valve collets are tight, apply pressure to valve spring retainer before removing so that the valve collets are detached.
Valves must not strike the piston crown otherwise they will be bent.
9 Remove top valve spring retainer and valve springs.
Removing valve springs of inlet / exhaust valves with 7.0 mm valve stem and 1-groove valve collets
1-groove valve collets Installed as of engine end number:
980 026 777
981 005 052
982
983





10 Insert guide bush (10) into bucket tappet hole.
11 Assemble thrust fork (6) with lever handle (3).
12 Insert assembly cartridge (8) into the guide bush (10), attach thrust fork (6) to the mating bearing (19) and move against the pin of the assembly cartridge (8).
13 Apply slight pressure to thrust fork (6) and to knurled screw and at the same time slowly turn the knurled screw of the assembly cartridge (9) (arrow) until the internal locating drift is felt to engage with its tips between the valve collets.





14 Apply slight pressure to the knurled screw (arrow) of the assembly cartridge (8) and press down thrust fork (6) as far as a stop (use extension if necessary). The valves are removed automatically.
15 Release pressure on thrust fork (6) and take off.
16 Take out assembly cartridge (8) with removed valve collets.
The valve collets can remain in the assembly cartridge until installed; however, if all the valve springs or valves are to be removed, e.g. with cylinder head removed, the valve collets can then betaken out of the assembly cartridge by pulling out the knurled screw.





Installation:
Place assembly cartridge (8) with the inserted valve collets into the guide bush (110). attach thrust fork (6) to mating bearing (19) and fit on slightly at the two pins of the assembly cartridge (8).
Press down thrust fork (6) as far as a stop. Pull the knurled screw of the assembly cartridge (8) up (arrow) and at the same time release the pressure on the thrust fork (6) (the valve collets are installed in this way).





17 Check whether the valve collets (21) are located in the assembly cartridge (8); repeat steps 10 to 13 if necessary.
18 Take out guide bush (10).
19 Remove top valve spring retainer and bottom valve spring.





20 Use pliers (1) 606 589 00 37 00 to pull off valve stem seal (86).
21 Inspect surface of valve stems for roughness and formation of burrs (visual inspection and with nail).
Replace valves with rough stem surface or burrs.
22 Remove bottom valve spring retainer and inspect for pitting, replace if necessary.





23 Fit protective cap (86a) (contained in parts kit) onto the valve stem and oil thoroughly
24 Push new valve stem seal (86) into assembly drift (2) and press onto the valve stem as far as a stop.
if assembly drift 119 589 00 43 00 1st version is used, widen its inner 0 to 7.5 mm.
24 Takeoff protective cap (86a).
Assembly drift (2) 104 589 01 43 00 (8mm exhaust valve)
Assembly drift (2) 119 589 00 43 00 (7 mm inlet, exhaust valve)

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