Ohv

valve & use. No adjustment

(To Identiiy Items, Reier to Illus. 56)

Thoroughly clean exterior of pump in gasoline or cleaning solvent before disassembling.

Servicing Oil Pump (O.H.V. Engine)

(To Identiiy Items, Reier to Illus. 56)

Oil feed pump and scavenger (oil return) pump are gear type pumps incorporated in one pump body. Feed pump incorporates an automatic (centrifugal) by-Dass valve, reducing oil feed supply at low engine speeds and increasing supply at high engine speeds. Pump is provided with check valve (11) and adjustable pressure regulating valve (16). Maximum pressure is approximately 30 pounds per sq. in.

Thoroughly clean exterior of pump in gasoline or cleaning solvent before disassembling.

With cover (29), governor rotor (28) and cover plate (26) and gasket (27), already removed, scavenger pump gears (wide gears) (22) and (23) are exposed. Scavenger pump gear (23) is keyed on pump drive shaft (8) and idler gear (22) idles on stud in pump body.

Remove lock ring (24) from end of pump drive shaft and slide gears off shaft and stud respectively. Remove scavenger pump gear key (21) from pump drive shaft.

Drive shaft can now be pulled out of pump body. Oil feed pump gears (narrow gears) (5) and (6) are now free for removal, however, gear (6) may come out with drive shait. Remove drive gear key (7) from drive shaft.

Remove chamber cap screws (9) and (13), adjusting screw (14), springs (10) and (15) and valves (11) and (16).

Remove front chain oiler adjusting screw (17) and adjusting screw washers (18) and (19). If pump is fitted with rear chain oiler, remove adjusting screw and adjusting screw washers.

Clean all parts in gasoline or cleaning solvent and blow out all pump body passages with air.

Using a light, inspect valve seats in pump body for pits and for dirty condition. Note: A small particle of foreign matter lodged on valve seat will prevent valve from seating, thus preventing correct operation of pump. Replace pump body if seats are damaged.

Inspect springs for breakage and rusted condition. Replace if not in good condition. Free length of new pressure regulating (by-pass) valve spring (15) is approximately 1-31/32".

Check valve spring (10) is the same for all pumps but is not interchangeable with any pressure regulating (by-pass) valve spring. It is much lighter (has less tension) than pressure regulating (by-pass) valve spring. Free length of check valve spring is approximately 1-9/32".

Valves (11) and (16) ^re interchangeable for check valve or pressure regulating (by-pass) valve and aie the same for all pumps. Valves may have rings formed by action on valve seats. Valves not perfectly smooth and round should be replaced.

Governor rotor (28) and rotor chamber in pump cover (29) ordinarily show no appreciable wear, and very seldom need replacing. 1948 pump only

Make sure that all parts and valve seats and all passages in pump body are thoroughly clean and free from dust, dirt, or grit before assembling. Also make sure valve in governor rotor (28) works freely, as a sticking valve will likely result in over-oiling at lower speeds.

Install check valve (11) and spring (10) and secure with cap screw (9). Install pressure regulating (bypass) valve (16), spring (15), and adjusting screw (14), turning in adjusting screw until end of screw is %" below end of valve chamber. This is normal setting. See "Adjusting Oil Feed Pump,"

To complete assembling of oil pump reverse procedure followed in disassembling. Note that one of the three gear keys, (7), is smaller than other two— install this key in shaft for oil feed pump gear (6) (narrow gear).

Some pumps may have a thin (.003") spacer behind scavenger pump idler gear (22) and gear will be .497" wide. Other pumps will have no spacer behind scavenger pump idler gear and gear will be .500" wide. A gear .497" wide should be used with spacer but a gear .500" wide must not be used with spacer. To exceed a total of .500" for width of idler gear and thickness of spacer may cause gear to bind tight enough to result in serious damage to pump.

Note: If scavenger idler gear has a groove on one side starting between two gear teeth and extending nearly to stud hole, install it on stud with grooved side against pump body. If scavenger idler gear has a groove across stud hole and in line with gear teeth, install it on stud with groove side outward. Parts order scavenger idler gear has both the grooves just mentioned, one on each side; is .497" wide and can be installed in any O.H.V. Model scavenger pump.

If pump is fitted with rear chain oiler, install scavenger pump gear (23) on drive shaft with groove (between two gear teeth) outward.

Lock rings (1) and (24) are often damaged when removing them, therefore, it is advisable to install new ones when reassembling and installing pump. Make sure lock ring is securely engaged and seated in retaining groove.

Installing Oil Pump (O.H.V. Engine)

(To Identify Items, Refer to Illus. 56)

Examine pump gaskets closely. If they are in good condition they can be re-used. If condition is at all questionable, install new "factory-made" gaskets. Never use "home-made" gaskets because these gaskets have holes especially located for oil passages and if a hole is left out or put in wrong place, oiling system may be put completely out of commission. With pump assembled (except pump cover, rotor and cover plate) and pump body gasket (4) in position against crankcase, enter pump drive shaft in bushing in crankcase and mount pump on studs.

Install drive gear key (3) in shaft keyway, and install drive shaft gear (2) and lock ring (1). Use new lock ring and make sure it is securely engaged and seated in retaining groove. Insert flat head screw (20) and tighten securely. Note: Before installing drive shaft gear (2), install bearing oil seal ring (33) shown in Illus. 62.

Install cover plate gasket (25), cover plate (26), and cover gasket (27).

Install oil governor rotor (28) in pump cover (29). Start cover on mounting studs, turn pump drive shaft slowly and press lightly against cover until driving tongue on rotor (28) registers in slot in scavenger idler gear.

Install nuts (31) and (32) and lock washers on pump mounting studs, insert hexagon head screw (33) with washer and tighten nuts securely. Note that extension nut (32) is placed on left center stud.

Turn pump drive shaft and note whether or not it turns freely. If there is considerable bind, check pump to determine cause.

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