STANADYNE FUEL SYSTEM MODEL DB4 PUMP Caterpillar

Disassembly

Usage:

Disassemble the Fuel Pump

NOTE: Some photographs and illustrations in this book are of the DB2 Fuel Pump. The DB4 Fuel Pump is slightly different, but the procedures given are basically the same.

DB2 Fuel Pump

DB4 Fuel Pump

NOTE: The plate is a piece of 1/4" flat steel with six holes drilled through. Two holes 9.5 mm (.375 in) are drilled to attach the plate to 9S6363 Fixture Assembly. Three holes 9.5 mm (.375 in) are drilled to attach the fuel injection pump to the plate. One hole 69.85 mm (2.750 in) is drilled through the plate for clearance for the fuel injection pump shaft.

START BY:

a. remove fuel injection pump

NOTE: Maintain cleanliness at all times during this disassembly and assembly procedure. Keep the work area clean, the tools clean, and the mechanics hands clean at all times during this procedure.

NOTE: All seals and gaskets should be replaced during the assembly procedure.

1. Mount pump in fixture as shown.

2. Remove the O-ring seal from the front of the housing.

3. Put plug (1) in fitting (2). Put cap (3) on aneroid tube (4).

4. Remove clip (5) from rod (6).

5. Remove fitting (2) from the housing.

6. Instal plug (7) in the housing. Remove four bolts (8) that hold aneroid bracket (9). Remove bracket (9) and aneroid (10).

7. Remove three bolts (11) and washers, and governor control cover (12).

NOTE: As you remove the governor control cover, note how the solenoid assembly (13) is hooked in the governor control.

8. Remove two nuts (14), two electrical plugs (15), two washers, two nuts, and two seals. Remove the gasket and the solenoid assembly (13).

Mechanical Governor

Speed Droop Governor

9. Use 4C8053 Remover (L) to remove key (16) from the throttle shaft assembly. Remove spacer (18) from the throttle shaft assembly. Slide out throttle shaft assembly (17). Remove dashpot assembly (19) and damper spring (20).

Speed Droop Governor

Mechanical Governor

Speed Droop Governor

Mechanical Governor

Speed Droop Governor

10. Loosen guide stud (21). While holding the governor spring and components (22) together, remove guide stud (21), and the governor spring and components (22).

11. While depressing the metering valve assembly (23), raise the governor linkage hook assembly (24) from the metering valve arm pin. Disengage the linkage hook assembly (24) from governor arm and lay the linkage hook assembly (24) over the side of the housing.

12. Remove the metering valve assembly (23).

13. Remove vent wire screw assembly (25).

14. Remove cap locking screw (26), plate (27), and seal (28).

15. Remove end cap assembly (29) using 4C6989 Socket (D).

16. Remove regulating assembly (30) from the end cap.

17. Remove inlet filter screen (31).

18. Remove plug (32), spring (33), and piston (34) from regulating assembly (30).

NOTE: Some Fuel Injection Pumps have a bushing pressed into the regulator instead of a seal. The bushing should not be removed and the seal is not required if the bushing is present.

19. Remove four blades (35), two springs (36), and liner (37).

20. Remove O-ring seal (38).

21. Loosen two locking head screws (39 & 40). Remove one of them.

22. Invert the pump and holding fixture in the vise. Loosen and remove head locating screw (41).

23. Remove O-ring seal (42) from head locating screw (41).

24. Remove advance plug (43) and seal.

NOTE: Tap lightly with hammer to loosen plug.

25. Remove cam plug (44) with tweezers (45).

26. Using 4C8129 Wrench (E), remove spring side advance piston hole plug (46). Remove power side advance piston hole plug (47). Remove two seals from each plug.

27. Remove piston retainer (48), piston (49), and spring (50), with the spring guide.

NOTE: Position the pump so the head is down.

28. Remove head locking screw (previously left loose).

29. Carefully remove hydraulic head assembly (51) with a slight rotary motion.

30. Remove thrust sleeve (52) and thrust washer (53) behind the sleeve.

31. Remove six weights (54).

32. Remove one pivot shaft retainer nut and seal (55).

33. Remove the pivot shaft (57) and governor arm (56).

34. Remove the snap ring (58) located on the back side of the drive shaft. Slide out drive shaft (61), spring washer (59), and thrust washer (60).

35. Remove brass thrust snap ring (62).

36. Remove liner locating ring (64) and two rotor retainers (63).

37. Remove rotor assembly (66) from head assembly (65).

38. Remove cam ring (67).

NOTE: Note the direction of arrow on cam ring (67) for later assembly.

Show/hide table

NOTICE

Do not handle the ground surface of the rotor.

NOTE: Scribe location of retainer assembly (70) to rotor assembly (66) so it is assembled in the same position.

39. Remove retainer clips (68) and retainers (69).

40. Remove rotor assembly (66) from retainer assembly (70). Remove rubber grommets (71) from rotor assembly (66).

41. Remove screws (72), leaf spring (73), four plungers (74), four rollers (75), and four shoes (76).

42. Remove plug from motor.

43. Using 4C6827 Hex Bit Driver, remove delivery valve stop screw (80). The delivery valve stop (79) and spring (78) may now be removed. Discard the delivery valve stop. If the delivery valve does not slide freely from its bore use 4C8128 Extractor (J) to remove it.

NOTE: Delivery valve (77) is specific to each fuel injection pump. If replacing this valve, contact Caterpillar Service Technology Group (CSTG) for the correct specification and part number. Refer to the TMI.