Pressure Relief Valve; Description; Inspection; Breather Assembly - Generac Power Systems GN190H Service And Repair Manual

SECTION 12: LUBRICATION

PRESSURE RELIEF VALVE

DESCRIPTION:

The ball type pressure relief valve is located in a bore of the
crankcase. The ball and spring are held in place by a retainer.
The valve serves to limit oil pressure to a maximum value. The
ball will remain against its seat as long as oil pressure is
below about 30 psi (29 kg/cm ). Should oil pressure increase
above that value, the ball will be forced off its seat to relieve
excess pressure into the crankcase (see Figure 12.6).
Figure 12.6 — Oil Pressure Relief Valve

INSPECTION:

Remove the SCREW that retains the RETAINER to the
crankcase. Remove the RETAINER, SPRING and BALL (Figure
12.6).
Clean all parts in solvent.
Inspect the BALL and RETAINER for damage, wear. Replace
any damaged or worn part. Inspect the SPRING, replace if
damaged or worn.
Apply a known test load to the spring, sufficient to com-
press the spring to a length of 1.03 inch (26.3mm). The
amount of test load at the stated spring length should be
within the following limits:
0.85-0.95 pounds (0.43-0.39kg)
Replace the spring if the test load at the stated length is
not within limits.

BREATHER ASSEMBLY

DESCRIPTION:
A crankcase breather is located in the rocker arm cover of
horizontal crankshaft engines (Figure 12.7). The breather
serves to maintain a reduced pressure in the engine crankcase,
to prevent oil from being forced past the oil seals, gaskets or
piston rings.
1
2
3
4
1. SCREW
2. RETAINER
3. SPRING
4. BALL
The CHECK VALVE allows excess pressure to be vented out
of the crankcase and to atmosphere through the BREATHER
TUBE. Two small DRAIN HOLES allow condensed oil vapors
to return to the crankcase.
NOTE: The crankcase breather on vertical shaft GN series
engines is mounted on the crankcase assembly and is
configured differently. See "SERVICE MANUAL — COM-
PUTER CONTROLLED VARIABLE SPEED RV GENERATORS,"
Manual Part No.94468-A.
DRAIN
HOLE
ROCKER
ARM
COVER
Figure 12.7 — Crankcase Breather
INSPECTION:
1. Remove the breather tube. Check tube for cracks, hard-
ening or other damage. Replace if necessary.
2. Clean the rocker arm cover in commercial solvent.
3. Make sure the two small drain holes are open. If neces-
sary, use a length of wire to open the holes.
4. Check the rivets that retain the check valve, make sure they
are tight.
5. The breather plate is retained in the rocker arm cover with
a continuous bead of Type 103 black RTV sealant. This
sealant must not leak. Test the sealant for leakage as follows:
a. Seal all holes on the breather plate.
b. Apply air pressure of 5 psi (0.352 kg/cm ) through the
breather hose hole. No leakage must be observed.
c. If necessary, reseal the plate with Type 103 black RTV
sealant.

CRANKCASE COVER

DESCRIPTION:
The die-cast aluminum crankcase cover is retained to the
crankcase with six flanged head bolts.
Install a new gasket between the cover and crankcase each
time the cover is removed. Bores are provided in the cover
48
CHECK
VALVE
BREATHER
TUBE