Check Compression; Cylinder Leak Down Test - Briggs & Stratton 5 HP Troubleshooting & Repair Manual

5 HP Outboard • Troubleshooting & Repair Manual
Section 2 • Troubleshooting
Figure 17 — Shift Lever Continuity Test
9
NOTE:
Local laws may require the use of a
resistor spark plug to suppress ignition signals. If an
engine was originally equipped with a resistor spark
plug, be sure to use a resistor spark plug for
replacement.

Check Compression

If compression is poor, look for:
Loose Spark Plug
Loose cylinder head bolts
Blown cylinder head gasket
Burned valves or valve seats
Insufficient valve clearance
Warped or worn valve stems and guides
Worn bore and/or piston rings
Broken connecting rod

Cylinder Leak Down Test

1. Run engine for 5 minutes, allowing engine to reach
operating temperature.
NOTE:
If the engine is cold or cannot be started,
airflow may be higher (gauge readings lower) because
compression components are not at normal
operating temperatures.
2. Remove spark plug from engine. Disconnect crankcase
breather tube.
3. Rotate crankshaft in direction of operation until piston
is at top dead center (TDC) of compression stroke.
4. Hold flywheel nut with 15/16" socket and 1/2" breaker
bar
(Figure 18).
Figure 18 — Holding The Flywheel
CAUTION
Injury may occur if the
crankshaft is allowed to
rotate.The crankshaft must be
held with the piston at top dead
center to eliminate any chance of
rotation..
5. Connect tester (#19545) to a shop air source with
minimum air pressure of 70 psi (480 KPA).
6. Install outlet hose into spark plug hole of cylinder
being tested. Insure o-ring is seated to prevent air leak
at spark plug hole. Connect other end to tester.
7. While securely holding the flywheel nut with the
breaker bar and socket, pull the knob lock out in the
direction of the arrow
adjustment knob
(Figure 19)
tester's needle is on the set point. Push in regulator
adjustment knob.
Figure 19 — Adjusting Compression Tester
17
Slowly turn the regulator
.
clockwise until
1
1
2