300E 4MATIC (124.230) L6-3.0L (103.985) (1990)
B. BLEED VALVE FOR CENTRAL DIFFERENTIAL LOCK (ZS) CLUTCH
As of May 1991 production, the transfer case is equipped with an additional bleed valve (EZS) to bleed the hydraulic lines and the piston area of the
central differential lock (ZS) clutch (Figure 3).
C. MULTIPLE-DISC CLUTCH FOR FRONT WHEEL DRIVE (AV) WITHOUT CONTACT PRESSURE
To increase comfort, contact pressure is no longer applied to the front wheel drive (AV) clutch. As a result, the oil flow limiting valves in the hydraulic
unit have been eliminated. When performing the Hydraulic System Test, the following tests, as described in the Model Year 1990 Introduction Manual
for 4MATlC, are no longer required:
"Application Pressure of Front Wheel Drive (AV) Multi-Disc Clutch",
"Checking Residual Pressure in Return Line N".