1997 W210 E320, please see attachment. Within 2 or 3 minutes of switching the A/C on, oil starts spewing from the stem on top of the R/D (see arrow in attachment). The aux fan is not coming on (a separate problem being diagnosed), and gauges show pressure of almost 425 until a box fan is held in front of the car, lowering pressure to about 350. I just got done replacing a leaky hose, and now this. Please someone tell me this is a pressure relief valve!

Attached Thumbnails

 

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

Its a pressure relief valve... fix the fan!

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Thanks for confirming! I have the new fan in hand and will be installing tomorrow.

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280