A worn blower drive, resulting in a rattling noise inside
the blower, may be detected by grasping the top rotor
firmly and attempting to rotate it. Rotors may move
from 3/8" to 5/8", measured at the lobe crown, with a
springing action. When released, the rotors should
move back at least 1/4". If the rotors cannot be moved
as directed above, or if the rotors move too freely,
inspect the flexible blower drive coupling and replace it
If the drive coupling is worn, the blower drive gear
assembly may be removed from the cylinder block end
plate after the blower has been removed from the
engine and the drive gear hub bearing support to
cylinder block end plate bolts are removed (refer to
Fig. 2 Typical Blower Mounting (71 Engine)
Loose rotor shafts or damaged bearings will cause
4. Loosen the water pump connections at the pump
rubbing and scoring between the crowns of the rotor
cover (inlet) and the cylinder block.
lobes and the mating rotor roots, between the rotors and
the end plates, or between the rotors and the housing.
5. Disconnect the control wire from the shutdown valve
Generally, a combination of these conditions exists. A
shaft lever, then remove the bolt securing the control
loose shaft usually causes rubbing between the rotors
wire clip to the air shutdown housing.
and the end plates. Worn or damaged bearings will
cause rubbing between the mating rotor lobes at some
6. Remove the air cleaner air ducts, then remove the
point or perhaps allow the rotor assemblies to rub the
air inlet housing, gasket, striker plate and air inlet screen
blower housing. This condition will usually show up at
and gasket from the blower.
the end where the bearings have failed.
7. Remove the blower drive shaft as outlined on Page
Excessive backlash between the blower timing gears
usually results in the rotor lobes rubbing throughout their
8. Loosen the blower drive shaft cover seal clamp (114
Fig. I) at the blower drive gear hub support.
To correct any of the above conditions, remove the
blower from the engine and either repair or replace it.
9. Remove the bolts and plain washers securing the
blower to the cylinder block. Slide the blower slightly
Inspect the blower inlet screen periodically as noted on
forward, withdraw the blower drive shaft cover from the
Page 10-11-3 for an accumulation of dirt which, after
seal, then lift the blower away from the cylinder block.
prolonged operation, may affect the air flow. Servicing
of the screen consists of thoroughly washing it in fuel oil
Remove Accessories from Blower
and cleaning with a stiff brush until the screen is free of
all the dirt deposits (refer to Page 10-1 1-7).
1. Remove the three bolts and seal washer assembly
securing the fuel pump to the blower rear end plate
Remove Blower In most cases, removal of the blower,
cover, then remove the fuel pump, gasket and drive
together with the governor drive, fresh water pump, fuel
oil pump, and the blower drive shaft cover, will be found
most advantageous. For removal of this assembly,
2. Loosen the seal clamp securing the blower drive
refer to Fig. 2 and proceed as follows:
shaft cover to the blower end plate cover, then remove
cover, seal and clamp from the end plate cover.
1. Drain the cooling system.
3. Remove the three bolts and seal washer assembly
2. Remove the governor control housing assembly as
securing the fresh water pump to the blower front end
plate cover, then remove the water pump and gasket. If
variable speed governor.
necessary, tap the pump with a plastic hammer to
3. Disconnect the fuel lines at the fuel pump.