It is not necessary to remove valve tappets and valve tappet guides to service the oil pump.

The breather is a part of and drives the oil pump. When removing the oil pump, the breather will of course come out with it. Removing the pump does not require removing the circuit breaker, gearcase cover or removing timing gears. However, it must be remembered that in order to correctly time

Figure 3D-10. Oil Pump - Exploded View

1. Oil pressure switch

2. Oil pump nipple

3. Check valve spring

4. Ball valve

5. Body Plate

6. Body plate gasket

7. Retaining ring

8. Scavenger pump gear

9. Scavenger pump idler gear

10. Breather valve key

11. Oil pump cover

12. Body cover gasket

13. Pump gear

14. Pump idler gear

15. Oil pump seal

16. Oil pump body

17. Body gasket

18. Drive lock pin

19. Breather valve gear and shaft

20. Crankcase breather valve screen

21. Idler gear shaft

Figure 3D-10. Oil Pump - Exploded View breather and to check oil pump alignment, it is necessary to remove these parts.

See Fig. 3D-10. Thoroughly clean exterior of pump in gasoline or cleaning solvent before further disassembly. Remove the five crankcase stud nuts that secure the oil pump to the crankcase. Slip the pump off the studs as one unit. If difficult to remove, take a piece of brass and tap on breather sleeve that extends into gearcase compartment. To disassemble the check valve see "Disassembling Oil Pump Check Valve."

Free the oil pump body plate (5) from pump body. Discard gasket (6). Remove retaining ring (7) (with "Tru-Arc" pliers) or split key 7A. Remove scavenger gears 8 and 9). Remove key (10). Free oil feed pump cover (11) and breather valve (19) as one assembly from pump body. Discard gasket (12). Free gears (13 and 14) from pump body. Pry oil seal (15) from pump body (16) and discard seal. Discard gasket (17).

With a punch remove lock pin (18) and free oil pump breather valve gear and shaft (19) from oil pump cover (11).

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