Honda WB20XT2 Manual page 94

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WB20XT2•WB30XT2
WATER PUMP VACUUM TEST
Use the water pump vacuum tester to confirm the pump
develops the proper suction vacuum, ensuring it will prime
and operate properly.
TOOLS:
Water Pump Vacuum Tester
Install thread tape or sealant to the vacuum gauge and install
in the base plate.
Fill the pump housing with water.
Position a garden hose in the discharge port and turn the hose
on so a steady stream of water flows out the port. This will
ensure the pump housing remains completely full during the
test.
Start the engine, position the throttle lever in the fast position,
and allow the engine to warm up for several minutes.
Adjust the maximum engine rpm to the proper no-load
specification.
Position the vacuum tester against the suction port to obtain
the vacuum reading.
Minimum Vacuum: 22 inches of mercury (in. Hg) at
sea level
Vacuum reading will decrease by approximately
1 in. Hg per 1000 ft increase in elevation.
Shut off the engine and confirm the vacuum gauge
reading remains steady. This verifies the intake flapper
is sealing.
VACUUM TEST RESULTS
If the vacuum gauge won't remain steady after shutting off the engine, disassemble and inspect the flapper for
wear or damage.
A vacuum reading below 22 inches of mercury (at sea level) indicates a problem with the pump. If the vacuum
is low, disassemble the pump and inspect the:
• Impeller and volute for damage or wear. Check the impeller/volute clearance.
• Mechanical seal for damage.
• Pump case housing and O-rings for damage or leaks.
MAINTENANCE
If the customer complains that the pump won't prime, but the vacuum reading is good, the customer likely has
an air leak in the suction hose or fittings, or the suction head is too high.
If the vacuum gauge needle does not return to zero, pull out the spigot on the top of the gauge to allow the
gauge to vent, and then press the spigot back in.
The gauge is filled with glycerin. If the fluid level gets low, remove the top plug and add glycerin, available from
many local hydraulic supply houses. Glycerin is available in 1-pint bottles, part number 3910K816, from
McMaster Carr Supply Company, telephone 330-995-5500.
07APJ-YB3A100
PUMP
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