Be sure to use shims with an .344 in. inside diameter. Either spring retainer may be used with
shims which have a .750 in. I.D. However, do not use the .344 in. I.D. shims with a spring retainer
which has only one air bleed hole.
Insert variable speed spring in spring plunger with tightly wound end of spring against shims.
Insert bolts through spring housing. Place a new gasket over bolts and against housing.
Place spring housing in position against control housing with spring plunger engaged in end of variable
speed spring. Thread bolts in control housing and tighten them securely.
Section V. Air Shutdown Housing and Blower
a. Air Shutdown Housing. The air shutdown housing is mounted on right side of engine on blower, and serves as a
mounting for air cleaner. The air shutdown housing contains an air shutdown valve that shuts off air supply and stops
engine whenever abnormal operating conditions require an emergency shutdown.
(1) The blower assembly, mounted on right rear side of engine block, supplies fresh air required for
combustion and scavenging. Two hollow double-lobe rotors revolve in rotor housing. The revolving motion of rotors
provides a continuous and uniform displacement of air.
(2) Gears located at splined ends of rotor shafts assist in spacing rotor lobes. Normal gear wear will have
some effect on rotor-to-rotor clearance. A combination of gear and rotor shaft bearing surface wear will result in a
decrease of rotor-to-housing clearance.
(3) Oil seals, consisting of a fiber washer, O-ring, retainer, and seal spring are incorporated in each end of
6-11 Air shutdown housing disassembly
a. Refer to Figure 6-8 and disassemble blower as follows:
(1) Remove 10 bolts and lockwashers securing the end plate covers to blower front and rear end plates. Tap
ends of end plate covers with a plastic hammer to loosen covers from gaskets and dowel pins in end plates. Then,
remove covers and gaskets from endplates.
(2) Place a clean folded shop towel between rotors and a towel between rotor and housing to prevent rotors
from turning. Then, remove the bolt securing water pump drive coupling to blower rotor shaft.
(3) Thread an adapter (1/2 inch-20 threads) or adapter (9/16 inch-18) into water pump drive coupling, then
attach slide hammer and shaft to adapter and pull drive coupling from blower rotor shaft.
(4) Remove bolts, lockwashers, and plain washers securing blower rotor drive hub and drive hub plates to
blower rotor timing gear or drive gear, then remove drive hub plates and spacers from gear. If necessary, remove three
bolts, lockwashers, and plain washers securing drive plates to drive hub.