Volkswagen Workshop Service and Repair Manuals

Checking and adjustment conditions

• ◆ Engine oil temperature min 60 °C

A - Checking centrifugal advance with TDC sender

(specifications

• ‒ With ignition switched off connect ignition timing and engine speed tester (e. g. V.A.G 1367).
• ‒ If necessary use and aux. terminal to connect to terminal 1 off the ignition coil.
• ‒ Pull vacuum hoses off the distributor vacuum unit and seal off the retard unit vacuum hose.
• ‒ Start engine and run at idling speed
       (max. 1000 rpm)
• ‒ Note indicated advance angle = basic angle.
• ‒ Slowly increase engine speed. Beginning of advance is shown by higher number of degrees.

• ‒ Compare engine speed with test figure for start of advance
• ‒ Increase engine speed to next test speed.
• ‒ Read off advance angle on tester.
• ‒ Calculate centrifugal advance angle:

• ‒ Repeat check at other test speeds.

B - Checking centrifugal advance with stroboscope

(specification )

• ‒ Connect speed tester and stroboscope.
• ‒ Pull vacuum hose off distributor vacuum unit and seal off the retard unit vacuum hose.

• ‒ Start engine and run at idling speed.
• ‒ Check and if necessary adjust ignition timing.
• ‒ "Bring mark back" to the centre of the ignition timing mark.
• ‒ Advance angle = Basic angle - note.
• ‒ Slow increase engine speed.
  Commencement of advance is indicted by the notch moving away.
• ‒ Compare speed with test figure - start of advance-.
• ‒ Increase the engine speed.to the next test speed " Bring the mark back" to the centre of ignition timing mark and read off advance angle.
• ‒ Calculate advance angle:

• ‒ Repeat check at other test speeds.

C - Checking vacuum unit for leaks

Advance unit

• ‒ → Connect vacuum tester and vacuum pump to vacuum - advance - unit.
• ‒ Switch tester to throughflow.
• ‒ Using the pump, produce a vacuum of approx. 500 mbar.
• ‒ Switch tester so that vacuum is held on the vacuum unit side.
• ‒ Set vacuum on tester to 450 mbar.

• The vacuum must not drop more than 10 % within 1 minute.
  Otherwise the vacuum unit or the hose is leaking.

Retard unit

• ‒ Connect vacuum tester and vacuum pump to vacuum -retard - unit.
• ‒ Switch tester to throughflow.

• ‒ Using the pump, produce a vacuum of approx. 500 mbar.
• ‒ Switch tester so that vacuum is held on the vacuum unit side.
• ‒ Set vacuum on tester to 450 mbar.

• The vacuum must not drop more than 10 % within 1 minute. Otherwise the vacuum unit or the hose is leaking.

D - Checking vacuum timing control - advance -

(specifications )

• ‒ Connect engine speed and injection tester or stroboscope.

• ‒ → Connect vacuum advance unit.
• ‒ Switch tester to throughflow.
• ‒ Seal of the -retard- unit vacuum hose.
• ‒ Start engine and run at idling speed.

Checking with TDC sender:

• ‒ Note indicated advance angle = basic angle.

Checking with stroboscope:

• ‒ "Bring mark back" to centre of TDC mark.

• ‒ Note indicated advance angle -basic angle-.
• ‒ Produce vacuum with the pump until the timing for start to move away.
• ‒ Read off vacuum figure and compare with figure for start of advance.
• ‒ Increase vacuum further until figure give for end of advance is reached.

Checking with TDC sender:

• ‒ Read off advance angle and calculate vacuum advance.

Checking with stroboscope:

• ‒ "Bring mark back" to centre of TDC mark.

• ‒ Increase vacuum further. The ignition timing mark must not move away.

E - Checking vacuum -retard- control

(specifications )

• ‒ Connect ignition timing and speed tester or stroboscope.
• ‒ Start engine and run at idling speed.
• ‒ Check and if necessary adjust ignition timing.
• ‒ Pull both vacuum hoses of the vacuum unit and seal the vacuum hose from the retard unit.
• ‒ Adjust engine speed to approx.950 rpm.

Checking with stroboscope:

• ‒ "Bring mark back" to ignition timing mark.

• ‒ Compare retard angle with the specified figure for end of retard.