Generac Power Systems 941-2 Service Manual page 85

The breather serves to maintain a partial vacuum in
the engine crankcase, to prevent oil from being forced
past oil seals, gaskets or rings.
See Figure 6. A reed type breather valve permits
excess pressure to be vented out of the crankcase
and to atmosphere through a breather tube. A
breather retainer limits the movement of the breather
valve. Two small oil return holes in the breather cup
allow condensed oil vapors to drain back to the
crankcase. A "steel wool" type breather separator
separates the breather cup from the breather cover
and breather tube opening.
Figure 6. Breather Assembly
INSPECTION:
Remove the breather hose. Inspect it for cracks, dam-
age, hardening. Replace, if necessary.
Clean the breather cover and breather cup in com-
mercial solvent. Check that the two small drain holes
in the breather cup are open; open with a length of
wire, if necessary.
Inspect the rivets that retain the reed type breather
valve, make sure they are tight. Also check that the
valve seats flat on the breather cup around the entire
surface of the valve.
OIL SUMP
DESCRIPTION:
The die cast aluminum oil sump is retained to the
crankcase with six (6) flanged head bolts. Install a
new gasket between the oil sump and crankcase
each time the oil sump is removed.
Bores are provided in the oil sump for (a) oil pump
rotors and camshaft, (b) crankshaft, (c) governor gear
assembly, (d) oil pickup. Cored oil passages are pro-
vided from the pickup to the pump and from the pump
to the crankshaft bore.
INSPECTION:
Clean the oil sump and blow dry with compressed air.
Use compressed air to blow out all oil passages.
Inspect the sump for cracks, damage, etc. Check the
following bores in the oil sump for wear:
CRANKSHAFT BEARING BORE DIAMETER
GV-220 ENGINE
DESIGN DIAMETER: 1.104-1.105 inch (28.040-28.065mm)
WEAR LIMIT: 1.106 inch (28.092mm) Maximum
CAMSHAFT BEARING BORE DIAMETER
GV-220 ENGINE
DESIGN DIAMETER: 1.299-1.300 inch (33.00-33.03mm)
WEAR LIMIT: 1.302 inch (33.06mm) Maximum
OIL PUMP INNER ROTOR SHAFT DIAMETER
GV-220 ENGINE
DESIGN DIAMETER: 0.353-0.354 inch (8.969-8.987mm)
WEAR LIMIT: 0.352 inch (8.949mm) Minimum
OIL FILTER SUPPORT
An oil filter support and its gasket are retained to the
oil sump by four (4) M6-1.00 bolt.
A threaded bore is provided in the support for a low
oil pressure switch. This switch will protect the engine
against damaging low oil pressure by shutting the
engine down automatically if oil pressure should drop
below a pre-set low limit.
A high oil temperature switch is retained to the sup-
port by two (2) M5 screws and lockwashers. This
thermal sensor will protect the engine against damag-
ing high temperature conditions through automatic
shutdown.
Figure 7. Oil Filter Support
Section 5.1
ENGINE OIL SYSTEM
Page 5.1-3