I was speaking with George Murphy about my door lock problems, and he was kind enough to send me the following:

140 door lock problems

Recent experience with the vacuum pumps that provide door locking on 140 S-class cars has shown that in older cars, say 1995 to 1992- the lubricant on the door lock mechanism seems to be degrading after 10 year or so, causing more resistance for the vacuum actuator that operates the lock. If the computer detects two failures to lock, the computer "locks out" the vacuum pump, preventing future operation. If you pull and re-install the fuse for the pump, it works OK again for a few cycles, then locks out again.

A new (expensive) pump works OK for awhile, then locks out as before.

The solution is to dismantle the doors and clean and re-lubricate the mechanical parts of the lock mechanism operated by the vacuum actuator.

I have only tried this on one 12-year-old 140 class, but it did resolve the lockout problem with the original pump. You should also check that the pump delivers at least 2.2 bar pressure.


Regards,

George Murphy
MBCA Technical Director

865-482-9175 9am to 5pm ET M-F

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe