Draper 35891 handleiding
Handleiding
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6. Operations
Important: Before preparing or adjusting this product,
read and understand all the safety instructions listed in
this manual.
ALWAYS refer to the manufacturer’s service manual to
ensure the correct testing procedures and specications
are followed. It is recommended that additional tests
such as compression tests, cylinder leakage tests,
ignition timing checks are carried out to conrm the
vacuum gauge readings.
6.1 Analysing Engine Mechanical
Conditions Using Manifold Readings
(Refer to the diagnostic chart for examples of readings
that may be observed).
• Important Notes:
− The action of the needle on the gauge during
testing is more important to note rather than the
actual reading.
− Engine types will run with dierent manifold
vacuum pressures, depending on camshaft
prole, valve overlap and timing. For reference the
needle reading should be steady and between 16
to 21inHg.
− Manifold vacuum is also aected by altitude and it
will drop approximately 1inHg for every 1000feet
above sea level so this should also be taking into
consideration when assessing the readings.
1 Fig.
6.2 Basic Diagnostic Test
1. Run the engine until the normal operating
temperature is reached. Then switch o the engine.
2. Connect the vacuum gauge to a port directly on the
manifold or on the carburettor/throttle body below
the throttle buttery.
3. Start the engine and allow to idle, observe the gauge
reading as shown in the diagnostic testing.
– 8 –
EN
DiagnosticTesting
GaugeReading Cause
16 – 21inHg
Needle Steady
Normal
When throttle opened and
released, needle drops to
below 5inHg and then up to
25inHg. Then settles back
to original reading.
Normal
Steady but extremely low. Leaking intake manifold
system.
Faulty manifold or carburettor
base gasket.
Split vacuum hose.
EGR valve seized.
Steady but low. Retarded ignition timing.
Conrm using timing light
and reset to manufacturer’s
specication.
Slightly low and slowly
uctuating.
Over lean or rich mixture.
Check and reset as per
manufacturer’s specications.
Fluctuating between normal
and low readings.
Blown head gasket between 2
adjacent cylinders.
Carry out cylinder leakage
test.
Slightly lower than normal
even when throttle is
opened and released.
Worn piston rings.
Carry out compression test.
Regular drop between
normal and low reading.
Burnt Valve.
Normal until drops when
revs held at 3000rpm.
Restriction in exhaust system.
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Productinformatie
| Merk | Draper |
| Model | 35891 |
| Categorie | Niet gecategoriseerd |
| Taal | Nederlands |
| Grootte | 1727 MB |
