6-NFR DISTRIBUTING VALVE (cont)
CLEANING, INSPECTION, AND REPAIR (cont)
Remove choke plug from drycleaning solvent and dry with compressed air. Check that choke plug is clean and
Lightly coat threads of choke plug with compound consisting of one part graphite and two parts oil and install.
21. Clean, inspect, and repair slide valve bushing by the following:
Check that slide valve bushing is not scratched or scored.
Use plug gage and check depth of seat.
If slide valve seat is scratched or scored, use lapping compound and recondition.
Use Prussian blue and gage blocks and inspect for low spots on bearing surface.
Remove burrs from slide valve seat and regage.
Use a depth gage and measure clearance groove. If it is less than 0.005 inch (0.13 mm) deep, use a hacksaw blade
and recut. Do not cut deeper than 0.020 inch (0.51 mm).
22. Clean, inspect, and repair slide valve and graduating valve by the following:
Check that valves are not scratched, scored, or damaged. Replace damaged valves.
Use a micrometer and measure slide valve thickness from the bottom of the graduating valve seat. Replace
slide valve if thickness is less than 0.549 inch (13.94 mm).
Use a depth gage and measure depth of 1/8-inch (3.2 mm) slots in slide valve. Replace slide valve if depth of
slots is greater than 0.093 inch (2.36 mm).
Use flat gage and gauge thickness of graduating valve.
If graduating valve is within gage limits, use lapping compound and lap slide valves to slide valve seat by the
(1) Condition the valve by rubbing slide valve against seat several times with lapping compound. Remove burrs
and rough surface marks.