79-00-00
page 8
May 01/2007
Effectivity 914 Series
Edition 1 / Rev. 0
d02628
BRP-Rotax
Maintenance Manual
2.3) Suction pump (turbocharger oil circuit, only on 914 Series)
See Fig. 79-4
The suction pump (11) is of the same design as the main oil pump (12) and sits
on the extended common pump shaft (15).
The lubrication of the turbocharger shaft, which is supported on plain bearings,
is via a separate oil line (2) from the main oil pump.
The pressure valve (3) on the entry into the turbocharger housing prevents
flooding of the turbocharger (1) with engine oil by gravity after engine stop.
Operation of the pressure valve:
Oil pressure min. 1 bar (14.5 p.s.i.) keeps the ball valve open against the low
spring pressure and the oil flows almost unhindered to the bearing bore. Without
oil pressure the valve closes and stops the oil flow.
â– CAUTION: Oil loss combined with heavy smoke emission at engine start is
a strong indication of a defective check valve.
The oil emerging from the bearing bore collects in the oil sump (8). From there,
it is sucked off by the suction pump (11) via a separate line (9) and pumped back
to the oil tank via the ring hose nipple (10).
â—† NOTE: The suction pump is also a trochoid pump and, like the main oil
pump (12), is driven by the common oil pump shaft.
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