Diagnose door lock problems on 1977 to 1985 240D 300D 300CD 300TD 280E 280CE. For all 123 chassis cars with vacuum door locks from 1977 to 1985. Now you can finally fix those pesky vacuum door locks yourself! Failure is almost always caused by vacuum leaks in the system. This 24 page manual with 55 photographs will take you step by step through the process of quickly finding and repairing those leaks. Starting at the firewall and working all the way to the trunk/deck of your car, I will show you how to isolate the problems even without having to take the door panels off. (Book is bound with smudge resistant plastic covers)
To aid in trouble shooting you will need to acquire an inexpensive vacuum hand pump. Normal hand tools are the only other things you will need. For 1977 to 1980 cars I even have vacuum actuator repair kits available so you can replace any cracked diaphragms you may find.
PLEASE NOTE: as an added bonus I have included all the information contained in my 123 Door Maintenance Guide in the appendix of this manual (no need for you to purchase that separately). This will show you how to properly remove your door panels and do other related maintenance inside your doors while you are working on the vacuum door locks. There are even instructions on how to properly deactivate the automatic door locks if you should so choose.
NOTE: A hand pump vacuum tester is required to properly troubleshoot your vacuum door locks. This is one tool I think every Mercedes diesel owner needs to own. If you are having vacuum shutoff issues, hard break pedal or problems with your door locks not operating properly, then you must have this tool to troubleshoot those problems effectively. To order this tool separately look below.