B. USA Starting Model Year 1981

B. USA starting model year 1981






Note: At begin of test, yellow, orifice (63) should be installed.


Testing EGR




Connect vacuum tester between EGR valve (60) and straight connection of thermovalve (36). At idle, with throttle linkage at idle stop, no vacuum should be indicated. Advance control linkage until free travel of free travel rod is eliminated (do not pull on stop lever). The vacuum should now amount to 350-500 mbar.

If:
- Idle, no vacuum present. Vacuum of 350-500 mbar is attained. Proceed to "Checking EGR valve (60)" (below).
- Vacuum is present at idle, or vacuum not attained or exceeded. Continue with "Check vacuum lines".


Check vacuum lines




Check all vacuum lines for control of EGR and automatic transmission according to operating diagram vacuum line layout for correct connection and leaks. Blow through orifice (62) in vacuum tapping point, if required.




Check black vent line (arrow) from vacuum control valve to passenger compartment for free passage.


Check thermovalve 40°C / 104°F (36, color code blue)




Pull off white/brown vacuum line on diagonal connection of thermovalve.

Pull off white/purple/brown vacuum line on EGR valve and blow through.

If there is no passage, remove thermovalve.


Check switchover valve (64a)




Pull central plug (71) from valve plate (69). Connect test line between tapping point (black orifice, arrow) on vacuum line for brake unit and valve plate connection (1). Connect vacuum tester to connection (3). Close connection (2).

Vacuum readout at switchover:
Idle speed (throttle linkage at idle speed stop) "0" mbar.
Bridge idle speed (do not pull on stop lever) approx. 700-800 mbar.

Leak test:
Let throttle linkage return to idle speed stop, stop engine.

Vacuum should remain constant for approx. 2 minutes.

Pull closing cap from connection (2).

Bridge idle speed.

Vacuum should drop to "0".

If test values are not attained: Replace switchover valve (64a).


Check switchover valve (64b)




Pull central plug (71) from valve plate (69). Connect test line between tapping point (black orifice, arrow) on vacuum line brake unit and valve plate connection (1). Connect vacuum tester to connection (2).

Close connection (3), start engine.

Vacuum readout:
Idle speed (regulating linkage on idle speed stop) approx. 700-800 mbar.

Leak test:
Disconnect tapping point for test line (arrow). Stop engine, vacuum should remain constant for approx. 2 minutes.




Vacuum readout at switchover:
Throttle linkage at full throttle stop, vacuum should remain constant. Let throttle linkage return to idle speed stop and pull off test line.

Vacuum should drop to "0".

If test values are not attained, renew switchover valve (64b).


Checking EGR valve (60)

Start engine. Operate switchover valve (64a) by eliminating free travel "L" on free travel rod. Pull off vacuum line on EGR valve and plug-on again.

EGR valve should audibly close.

EGR valve not closing.



Replace EGR valve (60).


Testing vacuum control







Connect vacuum tester between EGR-valve (60) and straight connection of thermovalve (36a). Disconnect connecting rod (5) on ball head. Start engine, increase rpm to approx. 900/min. Place adjusting roller on vacuum control valve (65) and set lever against stop (arrow).

Note: Engage connecting rod after test.

If vacuum readout 150-190 mbar. Testing is complete.

If vacuum is above or below requirements.


Test orifice for free passage and blow out, if required.




If the vacuum is not within tolerance, install the next larger orifice if the vacuum is too high and the next smaller orifice if the vacuum is too low. If the specified vacuum is not attained by installing another orifice, replace vacuum control valve (65).

End of test