Volkswagen Workshop Service and Repair Manuals

Retard unit

• ‒ → Connect up vacuum tester V.A.G 1368 between intake manifold and vacuum retard unit. Set vacuum tester to throughflow.
• ‒ Start engine and let it idle.
• ‒ Pull off vacuum hose of vacuum advance unit.
• ‒ Set vacuum tester such that vacuum is held on vacuum unit end. The vacuum indicated may drop off by max. 10% in one minute. Otherwise vacuum unit to be renewed.

Advance unit

• ‒ Connect up vacuum tester between carburettor/intake manifold and vacuum advance unit. Set vacuum tester to throughflow.
• ‒ If applicable, pull off vacuum hose of vacuum retard unit.
• ‒ Select engine speed such that vacuum indicated on vacuum tester is higher than test specification for and of advance.

Note:

If no vacuum is indicated on the vacuum tester, the vacuum tap in the carburettor/intake manifold is clogged.

• ‒ Set vacuum tester such that vacuum is held on vacuum unit end. The vacuum indicated may drop off by max. 10% in one minute. Otherwise vacuum unit is to be renewed.

Checking vacuum advance

Specifications: distributor data =>page 28-46

Engine code JB

• ● Ignition switched off.

• ‒ → Connect up ignition tester V.A.G 1367 with clip-on trigger V.A.G 1367/8 or ignition tester V.A.G 1767.
• ‒ Connect up vacuum tester V.A.G 1368 between carburettor and vacuum advance unit.
• ‒ Set vacuum tester to throughflow.

• ‒ If applicable, pull vacuum hose off vacuum retard unit.
• ‒ Start engine.
• ‒ Increase engine speed if necessary to idling speed.

Checking with TDC sender

• ‒ Note down advance angle indicated as basic value.

Checking with stroboscopic lamp

• ‒ "Bring back notch" to ignition timing point reference mark and down advance angle indicated as basic value.

Continuation for both tests

• ‒ Increase engine speed until vacuum indicated on tester is higher than test specification for end of advance.
• ‒ Set vacuum tester such that vacuum is held on vacuum unit end.
• ‒ Increase engine speed if necessary to idling speed.

• ‒ Reduce vacuum on vacuum tester to specification - end of advance/start of advance -.
• ‒ Establish advance angle (when testing with stroboscopic lamp by "fetching back notch").
• ‒ Calculate vacuum advance:

• ‒ Compare advance angle to specified value.

Engine code HN

• ● Ignition switched off.

• ‒ → Connect up ignition tester V.A.G 1367 with clip-on trigger V.A.G 1367/8 or ignition tester V.A.G 1767.
• ‒ Start engine and let it idle.

Checking with TDC sender

Specifications: distributor data =>page 28-46 .

• ‒ Note down advance angle indicated as basic value.
• ‒ Pull vacuum hose off vacuum advance unit.
• ‒ Read advance angle off tester.
• ‒ Calculate vacuum advance angle:

• ‒ Compare advance angle to specified value for end of advance.

Checking with stroboscopic lamp

Specifications: distributor data =>page 28-46

• ‒ Check and necessary adjust ignition timing point.
• ‒ Pull vacuum hose off vacuum advance unit.
• ‒ Bring back TDC to reference mark on clutch bell housing. Read off and note down advance angle.
• ‒ Attach vacuum hose to vacuum advance unit.
• ‒ Bring back TDC mark to reference mark on clutch bell housing.
• ‒ Read advance angle off tester.
• ‒ Calculate vacuum advance angle:

• ‒ Compare advance angle to specified angle for end of advance.

Checking vacuum retard

Engine code JB

Specifications: distributor data =>page 28-46

• ● Ignition switched off.

• ‒ → Connect up ignition tester V.A.G 1367 with clip-on trigger V.A.G 1367/8 or ignition tester V.A.G 1767.
• ‒ Start engine.
• ‒ Pull vacuum hose off vacuum advance unit.
• ‒ Check ignition timing point and set to TDC if necessary.
• ‒ Pull vacuum hose off retard unit.
• ‒ Increase engine to idling speed.

Checking with TDC sender

• ‒ Read of angle and to specified value for end of advance.

Checking with stroboscopic

• ‒ "Bring back notch" and compare to angle indicated.