Generac Power Systems GP6500 Repair Manual

Page 48
CROW'S FOOT
Figure 15. Tightening the Jam Nut
INSTALL ROCKER ARM COVER
1. Use a new rocker arm cover gasket. Install the rocker
arm cover and retain with four screws.
RESULTS:
Adjust valves to specification and retest. If problem
continues, refer to Flow Chart.
TEST 36 – CHECK ENGINE / CYLINDER LEAK
DOWN TEST / COMPRESSION TEST
DISCUSSION:
Most engine problems may be classified as one or a
combination of the following:
• Willnotstart.
• Startshard.
• Lackofpower.
• Runsrough.
• Vibration.
• Overheating.
• Highoilconsumption.
DISCUSSION:
The Cylinder Leak Down Tester checks the sealing
(compression) ability of the engine by measuring air
leakage from the combustion chamber. Compression
loss can present many different symptoms. This test
is designed to detect the section of the engine where
the fault lies before disassembling the engine.
PROCEDURE:
1. Remove the spark plug.
2. Gain access to the flywheel. Remove the valve cover.
3. Rotate the engine crankshaft until the piston reaches top
dead center (TDC). Both valves should be closed.
4. Lock the flywheel at top dead center.
5. Attach cylinder leak down tester adapter to spark plug
hole.
6. Connect an air source of at least 90 psi to the leak down
tester.
7. Adjust the regulated pressure on the gauge to 80 psi.
8. Read the right hand gauge on the tester for cylinder
pressure. 20 percent leakage is normally acceptable.
Use good judgement, and listen for air escaping at the
carburetor, the exhaust, and the crankcase breather.
This will determine where the fault lies.
RESULTS:
• Airescapesatthecarburetor–checkintakevalve.
• Airescapesthroughtheexhaust–checkexhaustvalve.
• Airescapesthroughthebreather–checkpistonrings.
• Airescapesfromthecylinderhead–theheadgas-
ket should be replaced.
CHECK COMPRESSION:
To check engine compression, remove the spark plug.
Insert an automotive type compression gauge into
the spark plug hole. Crank the engine until there is
no further increase in pressure. The highest reading
obtained is the engine compression pressure.
M I N I M U M A L L OWA B L E C O M P R E S S I O N
PRESSURE COLD ENGINE – 60 psi
If compression is poor, look for one or more of the fol-
lowing causes:
• Loosecylinderheadbolts.
• Failedcylinderheadgasket.
• Burnedvalvesorvalveseats.
• Insufficientvalveclearance.
• Warpedcylinderhead.
• Warpedvalvestem.
• Wornorbrokenpistonring(s).
• Wornordamagedcylinderbore.
• Brokenconnectingrod.
• Wornvalveseatsorvalves.
• Wornvalveguides.
NOTE: Refer to Engine Service Manual Part
Number 0C1103A for further engine service infor-
mation on the 410cc engine.
TEST 38 – CHECK FLYWHEEL
DISCUSSION:
In Test 25, a spark tester was used to check for
engine ignition. If sparking or weak spark occurred,
one possible cause might be the ignition magneto.
This test will check the magnetism of the flywheel and
will check the flywheel key.
PART 3
DC CONTROL
SECTION 3.3
DIAGNOSTIC TESTS

Generac Power Systems GP6500 Specifications

General

Brand	Generac Power Systems
Model	GP6500
Category	Portable Generator
Language	English