I have a 1980 euro 500SE. The distributor has two vacuum lines; one for retard and one for advance. With the engine not running, I have tested both vacuum ports using a vacuum pump. The retard side (closest to the distributor housing) holds vacuum. The advance side (farthest away) does not. Does this indicate that the advance diaphragm is faulty? If it is, can the vacuum control unit be replaced independently of the entire distributor? Is it necessary to remove the distributor to perform this job? I appreciate this forum and the good job that the techs do. Thank you for all the help you provide. Jack

The distributor is so easy to remove that we always pull it to work on it. The diaphram is available separately. Its # is 000 158 57 18 if you have a 117.961 motor and is # 000 158 69 18 if you have a 177.963 motor.

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