Section 4 - Exhaust Systems - Briggs & Stratton Vanguard 05000 Manual

NOTE
: The crankshaft must be held with the
piston at top dead center to seal the combustion
chamber and eliminate any chance of rotation. If
the engine is installed in an application, the
equipment can often lock the crankshaft from
moving.
6. Pull out the regulator adjustment knob (A)
and turn knob counterclockwise as far as
it will go. Make sure air outlet valve ([B]
Fig. 3) is closed.
2
7. Connect the tester to a compressed air
source (minimum air pressure of 70 psi).
8. Install the outlet hose into the spark plug
hole of the cyli nder being tested. Be sure
O-ring is seated to prevent air leak at
spark plug hole. Connect other end to
tester.
9. Turn regulator adjustment knob clockwise
until the tester's needle is on the set point.
Push knob in to lock. Slowly open air
outlet valve and note position of needle on
gauge, Fig. 4.
34
Fig. 3
Fig. 4
NOTE
: Any air lea ks at the connections or
fittings of the tester will affect the accuracy of the
test.
10. Listen for air leaking from the cylinder
head gasket, carburetor, exhaust system
and the cylinder breather tube.
NOTE
: If a high flow of air is leaking from the
exhaust and carburetor, make sure the piston is
at TDC on the compression stroke.
• Air flowing between the cylinder and
cylinder head indicates that the cylinder
head gasket is leaking.
• Air flowing from the carburetor indicates
air is leaking past the intake valve and
seat.
• Air flowing from the exhaust system
indicates air is leaking past the exhaust
valve and seat.
• Air flowing from the cylinder breather
tube or high oil fill dipstick tube indicates
air is leaking past the piston rings.
COMPRESSION TEST RESULTS
Reading is Green but a
Replace head g asket,
small amount of air is
and re-test.
leaking from head
gasket.
Reading is Green with Look for problems not
minimum air leakage. compression related.
Reading is Yellow/Red
Look for a possible
or Red, and all the air is
problem with that
leaking from one
component.
component.
Reading is Red, and air
Check th at pisto n is at
is leaking from several
TDC on the
components.
compression stroke. If
reading does not
change, look for
problems beginning
with the component
that appeared to leak
the mo st air. Re-test
after r epair.