4
If any debris is detected, remove it and thoroughly clean the seat and then the poppet valve
face.
5
If damage to the valve or its seat is apparent, lap the poppet valve face with its seat, using a
very fine carborundum grinding paste and metal polish.
6
When all scores are eliminated, wash both the poppet valve face and its seat with gasoline
to remove all traces of the lapping compound, and then complete the lapping process using
metal polish.
7
When lapping is successfully completed, again thoroughly clean the poppet valve face and
its seat.
8
When dry, rotate the valve on its seat to make sure that there are no high spots.
9
When the poppet is correctly seated, install it, together with its spring.
10
Fit the pressure relief valve cap, test the dispenser and check that the pump delivers satisfac-
torily.
11.8.2 Lapping the Pressure Relief Poppet Stem
If the stem, attached to the lower end of the valve poppet, is too tight in its guide the pump will
deliver more than normal. To check and/or correct the fit of the stem in its guide perform the
following procedure:
CAUTION!
Avoid Dash Pot Damage
Do not, under any circumstances, reduce the diame-
ter of the valve stem, as this may destroy the dash
pot action and cause the by-pass valve to be very
noisy during operation.
1
Remove the valve poppet as described in Section 11.8.1.
2
Clean both the valve stem and its guide.
3
Using metal polish, polish the valve stem, rotating it occasionally, until it moves freely in and
out of its guide.
4
When the valve stem moves freely in its guide, install the poppet together with its spring.
5
Fit the pressure relief valve cap, test the dispenser and check that the pump delivers satisfac-
torily.
WM048523 Rev 08 01/2019 191
11 Suction Pumps
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