BRP Rotax 915 i A Series Maintenance Manual page 119

Special tools To measure the differential pressure the following special tools and equipment are
necessary.
Instruction Testing is carried out using the differential pressure test procedure.
Step
Value The maximum permissible pressure drop is 45 %.
Procedure if maximum permissible pressure drop is out of range:
Recheck the readings after operating the engine in a test run for at least 3 minutes. This
will allow the piston rings to be wetted with oil. Measure the pressure drop again as de-
scribed in the differential pressure test procedure. If the pressure loss is still out of range,
valve seat debris removal procedure must be carried out.
Valve seat debris removal procedure
Step
Effectivity: 915 i A Series
Rev. 1
BRP-Rotax
MAINTENANCE MANUAL LINE
Part number
Compressed air approx. 6 bar (80 psi).
n.a.
n.a
2 pressure gauges.
n.a
Orifice jet*, of 1 mm (0.04 in) inner diameter and 3 mm (0.12 in)
length. * or equivalent e.g. orifice diameter 0.040 in., long 0.0250
in., 60° degree approach angle according to AC43.13, latest
issue.
n.a
Adapter to spark plug thread.
n.a
Connect line.
Procedure
1 Operate the engine until the temperatures have stabilized for a period of 5
min (engine oil temperature between 50 to 70 °C (122 - 160 °F).
2 Starting with cylinder head 1 move piston to TDC position.
3 Remove the upper spark plugs. Prevent dirt or other foreign particles from
penetrating the engine (A).
4 Screw adaptor (1) into the spark plug thread and connect up the two pres-
sure gauges (2) with the orifice jet (3) between them (B).
Now put constant pressure, between 5.5-6 bar (80 psi) on the line and take
5
readings at pressure gauge (C).
6 Repeat this proceeding at all 4 cylinder heads.
Procedure
1 Remove the valve cover according to the latest Maintenance Manual
Heavy.
2 Turn the crankshaft into the position, so that the intake valve is closed.
Description
12–20–00
Page 9
June 01 2019