Preparations For Measurement - Bosch EFAW 210 A Bedienungsanweisung

1. Fild of Application
Tester EFAW 210 A is unsed tomeassure losss in the cylinders
of internat combustion engines. The principle of the test is to first
pressurize the cylinder under test and then to indicate in percen-
tage the pressure loss due to leakage. The pressure gauge built
into the unit has a measuring range from 0 to 100 %.
The piston of the cylinder under test must be positionen at TDC
of the ecompression stroke for the test. In order to locate this
point exactly the setting devixe 1 688 132 025 (TDC Locator) is
included with the accessories of Tester EFAW 210 A.
The tester is connected to the compressed air supply by means
of a commercially available pressure hose (ID 6-7 mm). Minimum
pressure at the tester: 4 bar. Maximum pressure 16 bar.
i Note pressure loss in the compressed-air line; this can be up
to 0.5 bar.
No condensate should get into tester (compressed aif supply
must incorporate a water trap).
2.

Preparations for Measurement

2.1 Removing Spark plugs
The engine should be running warm when measurements are
made. Do not take out the spark plugs until the engine has been
warmed up.
2.2 Findung TDC
The piston of the cylinder under test must be socated exactly at
TDC of the compression stroke. This can be done using the
setting device 1 688 132 025 (TDC Locator). It is used inthe
following way:
Place the rubber plug inthe spark plug hole.
With magnet, fix the inducator cylinder so that it is as vertical as
possible in the engine compartment and so that the small piston
in the cylinder can be easily observed.
Slowly crank the engine ba hand in the normal direction of
rotation. This can be done on almost all engines by using the
fastening bolt on the crankshaft belt-pulley. Another possibility is
to crank the engine by turing the fan. If this is not possible, then
crank the engine by shifting into the highest gear and pushing the
vehicle (not possible with automatic transmission). During the
compression strooke, the smail metal piston of the TDC Locator
will be pushed uphed upwards. If the dead center is even slightly
passed, the metal piston immediately moves downward. By
cranking the engine back and forth the exact TDC point can be
established.
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3. Measuring the Pressure Loss
- Connect the tester to compressed aif supply.
- Connect test nozzle 1 680 363 036.
- Turn the knurled sxrew of pressure regulating valve until the
measuring instrument indicates 23 +/-1 (Cal.).
- Decouple the calibrating nozzle. Measuring gauge must display
a pressure loss of 0 % (+/- 1 % tolerance). Check device
functionality.
- Screw the test hose into the spark plug thread (use the
appropriate connecting piece).
- Connect the test hose to the tester.
- Read off the pressure loss in percent on the instrument.
4. Test Evaluation
The pressure loss readings should not exceed the permissible
valuesgiven by the engine manufacurer (from experience,
max. 25%). Differences up to 2 scale marks – 4% loss of
pressure between the indivikual cylinders have no significance. In
case of larger leaks, these can be located since the escaping air
creates a noise which may be heard at the following points:
Noise heard at
Air filter, carburettor or
intake manifold
Exhaust manifold or exhaust
Oil filler neck
Coolant filler neck
(air bubbles in coolant)
If a pressure loss above the permissible limit is determined during
normal testing, a small amount of motor oil can be tntroduced into
the cylinder, through the spark plug hole, to locate the leak, In this
way, leaks caused by the piston and piston rings will temporarily
be sealed. Thus, if the pressure loss is considerably less after
introducing oil into the cylinder, the leak is at piston and piston
rings.
Greater pressure losses are possible on a new engine which hast
not been fully run in (less than 3500 miles) since the cylinders,
pistons and piston rings have not yet attained final smoothness.
Diferences in the readings for the individual cylinders of up to
2 scale marks = 4% pressure loss is insignificant (guiding value).
Possible defect point
Intake valve
Exhaust valve
Pistons, piston rings
Cylinder head or
cylinder-head gasket