Engine Vibrates Excessively; Breather Passing Oil; Excessive Oil Consumption - Tecumseh V-twin Technician's Handbook

ENGINE VIBRATES EXCESSIVELY

1. Detach and ground the high-tension leads from the
spark plugs. Check the PTO end of the crankshaft
for bends. Use a straight edge, square or a dial
indicator.
2. Check the engine mounting hardware for proper
torque. Check the platform for rigidity.
3. Isolate the engine, remove and check any attached
equipment for an out of balance condition. Start and
run the engine without anything attached.

BREATHER PASSING OIL

1. Check the oil level. Ensure the engine is not
overfilled. Verify the viscosity rating of the oil being
used is to specification.
2. Check the angle of operation. Avoid prolonged use
at severe angles.
3. Check for excessive engine R.P.M. Use a vibra-tach
or other tachometer to adjust to the specified R.P.M.
setting found on microfiche card # 30 or the computer
Parts Look Up system.
4. Check the crankcase for leaking or damaged
gaskets, seals, or "O"-rings. External leaks may not
be evident; however, an atmospheric pressure leak
may prevent the engine from achieving a crankcase
vacuum. Check the crankcase vacuum using a water
manometer or vacuum gauge.
5. Check the breather cover, cover gasket and reed
for damage, or improper installation.
6. Check cylinder compression. If the engine has weak
compression, determine the cause (worn rings,
leaking head gasket, or leaking valves). A cylinder
leak down tester can be used to further evaluate the
problem cylinder(s).
NOTE: Follow the tool manufacturer's procedures
to prevent further engine damage.

EXCESSIVE OIL CONSUMPTION

1. Check the oil level, oil viscosity, and oil condition.
Drain and fill to the proper level.
2. Check the angle of operation. Avoid prolonged use
at a severe angle.
3. Check for leaking or damaged gaskets, seals, or "O"-
rings. External leaks may not be evident; however,
a leak may prevent the engine from achieving a
crankcase vacuum.
9-2
4. Check for excessive engine R.P.M. Use a vibra-tach
or other tachometer to adjust to the specified R.P.M.
setting found on microfiche card # 30 or the computer
Parts Look Up system.
5. Check the breather cover, cover gasket and reed
for damage or improper installation.
6. Clean the cooling fins to prevent overheating.
7. Check the carburetor for a lean running condition
caused by restricted fuel passages.
8. Check the cylinder compression. If the engine has
weak compression, determine the cause (worn rings,
leaking head gasket, or leaking valves). A cylinder
leak-down tester can be used to further evaluate the
problem cylinder(s).
NOTE: Follow the tool manufactures procedures to
prevent further engine damage.
9. Check the valve guides for excessive wear.
10. Check the intake valve stem seal for wear or damage.
LACKS POWER
1. Check the air intake for an obstruction (plugged, dirty
or oil-saturated air filter).
2. Check the oil level, oil viscosity, and oil condition.
Replace and fill to the proper level.
3. Diagnose each of the spark plugs condition.
4. Check the carburetor(s) for improper choke plate
engagement, or a restricted fuel passage(s).
5. Check the exhaust port for a restriction preventing
proper exhaust flow. Thoroughly inspect the muffler
for loose baffles or an obstruction.
6. Check the engine valve lash. Reset the valves at
the proper clearance.
7. Check the valves for proper seating and valve guide
clearance. Recondition the valves and seats.
Replace the valves if necessary.
8. Check the ignition system operation. Use a gap type
spark tester installed between the high-tension lead
and the spark plug. Check the flywheel key for partial
shearing and the CDI module air gap.