19 Testing Engine For Leaks; Tools, Servicing Aids; Testing Compression Pressure - Stihl BR 800 Service Manual

19 Testing Engine for Leaks

19.1

Tools, Servicing Aids

Pump – 0000 850 1300
–
Sealing plate – 0000 855 8106
–
Socket, T27x125 – 0812 542 2104 or equivalent
–
Assembly drift – 1110 893 4700
–
Compression tester – 5910 850 2000
–
Test flange – 5910 850 4200
–
ZAT 3 ignition system tester – 5910 850 4520
–
Torque wrench – 5910 890 0302 or equivalent
–
Screwdriver, T27x200 – 5910 890 2415 or equivalent
–
19.2

Testing Compression Pressure

Preparations, @ 3.1.
N
Remove the cover, @ 7.4.
N
Pull boot off the spark plug.
N
Remove the spark plug.
N
WARNING
High voltages can occur at the spark plug boot during the
test. This can result in serious or fatal injuries.
Fit the ZAT 3 ignition system tested to ground the ignition
voltage.
1
2
Fit spark plug boot on the terminal (2) of the ZAT 3
N
ignition system tester 5910 850 4520.
Attach terminal (1) of ZAT 3 to the cylinder.
N
WARNING
High voltages can occur in parts of the ZAT 3 during the
test. This can result in serious or fatal injuries.
Hold the ZAT 3 only by the handle (3) during the test.
50
N
N
N
Compression pressure should be between 7.5 and 8.5
bar.
N
N
N
19.3
N
N
N
N
N
N
3
N
N
2
Screw the compression tester 5910 850 2000 (4) into
the spark plug hole as far as stop.
Operate the rewind starter.
Take compression pressure reading.
If compression pressure is lower than 7.5 bar: Check
valve clearance and readjust if necessary, @ 12.2.
If compression pressure is higher than 9 bar: Check
decompression system and replace cam gear if
necessary, @ 18.4.
If the required value is still not obtained: Check
cylinder, valve seats, piston and piston rings and
replace damaged parts.
Testing Engine for Leaks
Preparations, @ 3.1.
Remove the rewind starter, @ 6.2.
Remove the air filter, @ 7.2.
Remove the shroud, @ 7.4.
Remove filter housing and carburetor, @ 8.2.
If the spark plug has been removed: Insert and tighten
down the spark plug.
10
9
8
7
8
5
6
Loosen screws on muffler (12), @ 16.2.
Slide the sealing plate 0000 855 8106 (11) between
the exhaust port and muffler (12) so that it completely
fills the space between the two screws.
4
1
11
12
BR 800