d02880.fm
MAINTENANCE MANUAL
BRP-Powertrain
Effectivity: 912 Series
Edition 2 / Rev. 0
12-20-00
page 13
October 01/2009
5) Checking the compression
General note See Fig. 5.
Special tools To measure the compression pressure the following special tools and
equipment are necessary.
Instruction Testing is carried out using the differential pressure test procedure.
Value The maximum permissible pressure drop is 25 %, e.g. from 6 to 4.5 bar
(87 psi to 65 psi) (D).
If the pressure loss is less than 25% then the valve seats and piston rings
are working properly. The spark plug has to be installed according to
chap. 12-20-00 section: 14.2).
If the value is over 25% inspection, repair or overhaul must be carried out
in accordance with the BRP-Powertrain instructions for continued airwor-
thiness.
- Detailed inspection of affected engine components.
WARNUNG
WARNING
Risk of electric shock!
Ignition “OFF“ and system grounded!
Part number Description
n.a. Compressed air approx. 6 bar (87 psi).
n.a. 2 pressure gauges.
n.a. Orifice jet*, of 1mm (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.
Step 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 Started with cylinder head 1 move piston to TDC position.
3 Remove the upper spark plugs. Prevent dirt or other foreigner particles from
penetrating the engine (A).
4 Screw adaptor (1) into the spark plug thread and connect up the two pressure
gauges (2) with the orifice jet (3) between them (B).
5 Now put constant pressure, between 5,5-6 bar (80-87 psi) on the line and take
readings at pressure gauge (C).
6 Repeat this proceeding at all 4 cylinder heads.
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