Generac Power Systems MC - Manual (Page 35)

RESULT:- Float Valve, Seat, Gasket and
Float level are good.........
Float Valve, Seat, Gasket or
Float level check bad........ -...Continue Diagnostic Tests
-Replace or adjust, then test
TEST 24:- COMPRESSION
A.)-Insert a standard compression
gauge into engine spark plug hole.
Open throttle wide open and crank
engine. Compression should be app­
roximately 75-85 psi (cold) or 95-
105 psi (hot).
COMPRESSION
GAUGE
SPARK PLUG
REMOVED
RESULT:- Compression reading good...................... Go to Test 29
Compression reading low.......................Continue tests
B,)- Squirt a few drops of clean engine oil into spark plug hole on en­
gine cylinder head. Repeat compression test. If compression reading is
higher than was obtained in Paragraph A, ring or cylinder wear is indi­
cated, If little or no difference in compression was noted, trouble may
be due to head gasket leakage, worn valves, etc.
RESULT:- Noticeable increase in
compression obtained...............
Little or no increase in compression.
Go to Test 27
Go to Test 25
TEST 25:- HEAD GASKET
Crank the engine. A "hissing" sound
at the spark plug indicates the plug
is loose or broken. Likewise, "hiss­
ing" at the cylinder head indicates
loose head nuts or a leaking head
gasket. Tighten loose spark plug, re­
place broken spark plug using a new
plug gasket. If cylinder head leaks,
check for warped cylinder head and
for a defective head gasket. Refer to
engine section of manual and to TORQ­
UE SPECIFICATIONS (SPECIAL).
2.2-13