Multiquip T20H - Manual (Page 20)

PAGE 20 —STOW T-20H TRASH PUMP — PARTS MANUAL — REV. #0 (05/29/03)
STOW T-20H — MAINTENANCE (PUMP)
To perform the pump vacuum test do the following:
1. Remove the pump fill cap (Figure 2), and fill the pump
with water.
2. Start the engine as outlined in the initial start-up section,
and wait for the pump to begin pumping.
3. As shown in Figure 17 (next page), place a water hose
inside the discharge opening of the pump, and turn on
the water. This flow of water into the discharge opening
will
prevent the pump from running dry.
4. Place the Pump Vacuum Tester (P/N 7000030) over
the pump suction (inlet) opening (Figure 17) with the
vacuum gauge facing upwards. It may be necessary to
apply a small amount of water around the rubber seal of
the vacuum tester to make a good suction fit.
5. Check and make sure that there are no air leaks between
the vacuum tester and the inlet port on the pump. If air
leaks are present reseat vacuum tester.
6. Run the pump for a few minutes while monitoring the
vacuum gauge. If the gauge indicates a reading between
-25 and -20 in. Hg. (inches of mercury) then it can be
assumed that the pump is working correctly.
Pump Vacuum Test
CAUTION :
DO NOT attempt to start the engine unless
the pump has previously been
primed with
water. Severe pump damage will occur if
pump has not been primed.
Adjusting Impeller Clearance
1. If it is necessary to replace impeller or volute, be sure
clearance between impeller and volute is adjusted
correctly.
2. The impeller should be as close to the volute as possible
without rubbing against it. Clearance is adjusted by
adding or removing
shims from behind the impeller.
3. Check clearance between impeller and insert by slowly
pulling starter rope to turn impeller. Remove spark plug
to make it easier to turn impeller.
25 in. Hg (inches of mercury)
translates into 25 feet of lift at
sea
level.
NOTE
7. If the vacuum tester gauge indicates a reading
below -20 in. Hg, it can then be assumed that the pump
is not functioning correctly, and corrective action needs
to be taken.
6. To test the flapper valve, shut down the engine. The
vacuum tester should remain attached to the pump
suction inlet port by vacuum. This indicates the pump's
flapper valve is seating properly to hold water in the
suction hose when the engine is stopped. This prevents
backflow and allows for faster priming when the engine
is restarted.
It is important not to remove too
many shims or the clearance
between the impeller and volute
will become
too wide and pump
performance will be reduced.
Remember as the impeller wear
down, additional shims may be required to maintain the
clearance between the impeller and insert.
4. Check the impeller every six months for wear, and for
clearance between the impeller face and the volute. Also
check the shaft seal for wear, as well as the shaft sleeve.
Pump Cleaning
After pumping water containing large amounts of dirt and
debris, perform the following:
1. Remove the drain plug from the pump housing (Figure 2)
and drain any water left in the pump.
2. Loosen the two locking hand knobs (turn counter-
clockwise) and remove clean-out cover.
3. Clean and remove dirt, debris from pump casing. Inspect
impeller and volute for wear. Replace any damaged or
worn parts.
CAUTION :
The impeller may develop sharp edges.
Use extreme care when cleaning around
the impeller to prevent being cut.
NOTE