Rotax MMH-912 Series, Руководство по обслуживанию

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BRP-Rotax
Maintenance Manual
Effectivity 912/914 Series
Edition 1 / Rev. 2
72-00-00
page 57
July 01/2008
d04351
3.11) Cylinder head - disassembly
See Fig. 72-59.
If the rocker arms are to be dismantled without removing the cylinder head, turn
the crankshaft to set the piston of the respective cylinder to ignition T.D.C. so that
only little pressure remains on the rocker arm. Depress rocker arm with check
lever part no. 877690 towards the hydraulic valve tappet. Now the rocker arm is
completely released and the rocker arm shaft can be removed.
◆
NOTE: Never use force to press out the rocker arm shaft. The hexagon
of the collar cap nut may be in an unfavorable position and
prevent removal of the rocker arm shaft. In this case, loosen the
nut.
Withdraw rocker arm shaft and remove both rocker arms.
◆
NOTE: Newer engine versions have plastic bushings as bearings.
These plastic bushings must be laid aside in an ordered manner
to prevent any mixup.
Compress the valve springs using valve spring mounting device (1), part no.
877380, valve spring mounting pliers (2) or similar tool and lift out valve cotters.
Release valve spring. Remove valve spring retainer and both springs and
withdraw valve.
◆
NOTE: Prior to removal of valves, clear burrs which may be present on
valve stems to prevent damage to valve stem seal and valve
guide. Mark valves coordinately.
Repeat procedure for the second valve. Clean cylinder head.
Check oil return tubes for leaks (visual inspection). If there is leakage in area (3),
the respective oil return tubes must be replaced. For this procedure, heat the
return tubes with a hot air gun to max. 120 °C (248 °F).
Extract the oil return
tubes and remove any glue residues from the bore. Apply LOCTITE 648 on the
new oil return tubes in the area of the two grooves and twist and push tube into
position in the preheated cylinder head. After that heat the cylinder head 10 to
15 minutes to 100 °C (212 °F) so that the LOCTITE hardens.