OTC 5606 Test Procedure

Test Procedure
Test Procedure
1. Run the engine until it reaches
1. Run the engine until it reaches
normal operating temperature before
performing the compression test.
2. Stop the engine. Disconnect all the
normal operating temperature before
spark plug wires and number them
according to the cylinder they were
connected to. performing the compression test.
3. Loosen all spark plugs about one
turn, but do not remove them. Use an
air hose or stiff brush to remove all the
dirt from the spark plug wells. Remove
2. Stop the engine. Disconnect all the
the spark plugs and place them on a
clean, flat surface in the order according
to the cylinder they were removed from.
spark plug wires and number them
4. Remove the air filter and set the
throttle plates to the wide open throttle
according to the cylinder they were
position, being careful not to damage
the linkage or throttle components.
connected to.
CAUTION!
Failure to return throttle plates to closed
position before starting engine can
cause serious engine damage.
3. Loosen all spark plugs about one
5. Disable the ignition system. Follow
the manufacturer's recommendations, or
refer to a service manual for the proper
turn, but do not remove them. Use an
procedure.
6. Select the spark plug adapter and/or
hose required for the vehicle. Screw the air hose or stiff brush to remove all the
adapter and/or hose into a spark plug
well. Hand tighten only - DO NOT USE
A WRENCH. See Figure 1. dirt from the spark plug wells. Remove
NOTE: On engines with long reach
plugs, use the long reach hose. Do not
the spark plugs and place them on a
use the long reach hose in short reach
holes – it may hit the top of the piston
and damage the engine.
clean, flat surface in the order according
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to the cylinder they were removed from.
4. Remove the air filter and set the
throttle plates to the wide open throttle
position, being careful not to damage
the linkage or throttle components.
Failure to return throttle plates to closed
position before starting engine can
cause serious engine damage.
5. Disable the ignition system. Follow
the manufacturer's recommendations, or
refer to a service manual for the proper
procedure.
6. Select the spark plug adapter and/or
hose required for the vehicle. Screw the
adapter and/or hose into a spark plug
well. Hand tighten only - DO NOT USE
A WRENCH. See Figure 1.
NOTE: On engines with long reach
plugs, use the long reach hose. Do not
use the long reach hose in short reach
holes – it may hit the top of the piston
and damage the engine.
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5606 Compression Tester Kit
Figure 1
Installation of
Compression Gauge
7. Connect the coupling on the gauge
hose to the fitting on the spark plug
hose. Be sure the hose couplings are
fully engaged.
8. Crank the engine for at least five
compression strokes or until the
pressure reading stops rising on the
gauge.
9. Record the compression reading,
then push the side release valve to
relieve the pressure as shown in Figure
2. Repeat the test. Record the reading,
relieve the pressure, and remove the
hose from the spark plug well.
Figure 2
Push Release Valve
to Relieve Pressure
10. Reconnect the hose to the next
spark plug well to be tested and repeat
steps 6 through 10 for the remainder of
the cylinders to be tested.
CAUTION!
Test Results
1. On a normal cylinder, the gauge
needle should travel up-scale on each
compression stroke until it reaches a
peak value. All cylinders should indicate
a pressure that is within the vehicle
manufacturer's specifications, and the
reading should not vary more than 10%
from cylinder to cylinder.
2. If the needle fails to travel up-scale
as described in paragraph 1 above, or if
it remains at the same value for several
strokes and then starts to climb, the
cylinder may have a sticking valve.
3. If the compression reading is
considerably higher than the vehicle
manufacturer's specification, it may
indicate carbon build-up in the cylinder.
It may also indicate that the piston or
cylinder head has been modified.
4. If a reading on two adjacent cylinders
is 20 psi (or more) lower than the other
cylinders, a defective head gasket or
cracked cylinder head may be indicated.
Water (coolant) and oil may be found
in the two cylinders under these
conditions.
5. If the readings are low or vary widely
between cylinders, pour a teaspoon
of grade 30 oil into each cylinder
and retest. If the readings increase
considerably, the fault may be due to
poorly seated or worn piston rings. If
the readings remain about the same, the
valves and/or associated components
may be the cause. A burned or damaged
piston may also cause these results.
OTC
1-800-533-6127