Graco 3900 Paint Sprayer User Manual


 
309409 17
Displacement Pump
Removal
1. Flush pump.
2.
Relieve pressure; page 5.
3. Fig. 15. Cycle pump with piston rod (222) in its
lowest position.
4. Fig. 15. Remove suction tube (30) and hose (33).
Fig. 15
7672C
222
33
30
5. Fig. 16. Use screwdriver: push retaining spring up
and push out pin (29).
Fig. 16
7675B
29
6. Fig. 17. Loosen locknut by hitting firmly with a
20 oz (maximum) hammer. Unscrew pump.
Fig. 17
7673B
Repair
See manual 309277 for pump repair instructions.
Installation
WARNING
If pin works loose, parts could break off due to
force of pumping action. Parts could project
through the air and result in serious injury or prop-
erty damage. Make sure pin and retaining spring
are properly installed.
CAUTION
If the pump locknut loosens during operation, the
threads of the bearing housing will be damaged.
Make sure locknut is properly tightened.
1. Fig. 18. Pull piston rod out 1.5 in. Screw in pump
until holes in bearing cross link and piston rod
align.
Fig. 18
7676B
1.5 in.
2. Fig. 16. Push pin (29) into hole. And push retaining
spring into groove all the way around connecting
rod.
Fig. 19. Screw jam nut down onto pump until nut
stops. Screw pump up into bearing housing until it is
stopped by jam nut. Back off pump and jam nut to
align pump outlet to back. Tighten jam nut by hand,
then tap 1/8 to 1/4 turn with a 20 oz (maximum) ham-
mer to approximately 75" 5 ft–lb (102 Nm).
Fig. 19
7673B
Fig. 20. Fill packing nut with Graco TSL until fluid flows
onto the top of seal.
Fig. 20
7677B