Hydraulic Valve Tappets; Push Rods - Rotax 912 Series Maintenance Manual

14.7) Hydraulic valve tappets

See fig. 182, 183 and 184.
Remove valve tappet Q from crankcase using a specially shaped screwdriver W.
Never engage at circlip E. This would cause valve tappet to fall apart.
CAUTION:
2
00299
through bore T. The securing ring E keeps the valve tappet plunger Y in position
when the tappet is removed.
CAUTION:
fig.184

14.8) Push rods

See fig. 185.
Clean and inspect visually the push rods Q. Pay attention to tight fit of the two ball
2
Effectivity: 912 Series
AIRCRAFT ENGINES
MAINTENANCE MANUAL II
Lay aside tappets in a manner to ensure refitting in their initial place.
Visually inspect hydraulic valve tappets. The hydraulic
fig.182
tappets rotate during engine operation. Therefore, the cam-
shaft lobes
lic tappets to rotate properly will result in unevenly worn
3
camshaft lobes. Any visible pitting on the contact face of the
hydraulic tappet is a cause for part rejection and the tappet
1
must be replaced. It is not permissible to re-work the face of
the hydraulic tappet!
If a valve tappet must be renewed, closely inspect its
respective camshaft lobe. Disassembly of a hydraulic tap-
pet is not permitted.
The new valve tappet is supplied dry and will pump itself full
with oil during starting procedure. Oil enters the valve tappet
The first start of a repaired engine should be without ignition, until the
required oil pressure is built up.
3
00301
6
heads W pressed into the rod. If the engine has exceeded the
maximum admissible speed this may have caused bending of
the push rods. Check push rods supported on V-blocks for
straightness, see dim. G. Through the bores E oil passes from
Q
00302
fig.185
R
should be worn evenly. Failure of the hydrau-
00300
4
fig.183
3
2
5
the valve tappet to the
rocker arm.
page 113
Initial issue, Jan. 01/2002