SECTION IV. PRELUBE PUMP ASSEMBLY
GENERAL. The prelube pump B3 is a gear-type fluid pump and is operated by a 24V dc electric motor
coupled directly to the pump. The prelube pump B3 is equipped with a by-pass valve which provides pressure relief from
excessive discharge pressures which overheat the pump. Rotation of the motor and drive shaft is counter clockwise
when viewed from the pump side of the motor. Lubricating of oil enters the pump through the port adjacent the by-pass
valve, and is discharged through the port on the opposite side of the pump body. The prelube pump B3 provides initial
lubrication to the engine prior to engine start, and is manually operated by PRELUBE SYS switch S5 on panel C in the
generator set control room. The prelube pump B3 is bolted to the skid base by the right rear engine mount; when
operated, it draws of oil from the engine of oil sump and delivers R under pressure to the engine oil passages.
PRELUBE PUMP B3 DISASSEMBLY.
Remove the prelube pump B3 from the generator set skid base in accordance with the Operator and
Organizational Maintenance Manual.
Remove the machine screws (1, Figure 8-8) and lockwashers (2), and remove the motor (5) with the pump
assembly (8) from the motor base (4), if necessary.
Remove the grommets (3) from the motor base (4), if required.
Loosen the hexagon head capscrew (11) in the cover (12), and remove pump assembly (8) from the adapter
(6). Remove the machine screws (7) and remove the adapter (6) from the motor (5).
Remove the coupling (9) from the drive shaft (26).
Remove the plug nut (14) and fiber washer (13) from the cover (12).
The by-pass valve assembly (15) is factory set to 70 psi (483 kPa).
Disassemble the by-pass valve only if necessary. If disassembly is
required, count the number of turns required to turn out the
adjusting screw (19). During assembly, return the adjusting screw
(19) to this position, so that the approximate factory pressure
setting will be retained.
Remove the by-pass valve assembly (15) from the cover (12) by removing the valve nut (16), fiber washers
(1 7), locknut (18), adjusting screw (19), spring (20), and ball (21).
Do not pry the body (29) from the cover (12) using a sharp, a sharp
instrument such as a screwdriver or chisel as this may damage the
mating surfaces of the body and cover. If difficulty is experienced
in separating the body (29) from the cover (12), tap on the body
with a plastic or lead faced hammer.
Remove the machine screws (30), and remove the body (29) from the cover (12). Remove and discard the
Remove the idle shaft (24) and gear (23), and the drive shaft (26) and gear (25), from the cover (12).
Press the gear (23) from the idle shaft (24).
Press the pin (27) from the gear (25), and press the gear from the drive shaft (26).
Remove the carbon bearings (22) from the cover (12) and the body (29) only if worn. Check in accordance
with paragraph 8-18, step c, below.
Remove the lip seal (10) from the cover (12).