I am thinking about buying a 1981-1985 300D or 300SD. I know these cars suffer from vacuum problems that affect the door locks, windows and trans shifting. Is it mostly leaks from hoses or are there parts that are prone to failing, like the trans modulating valve? Can the repairs be made at home.

I have just completed the restoration of a 62 Olds Starfire convertible, so I am pretty good with a wrench.

 

If you are willing to take the time to leak check your system section by section until you've fixed it. Then no most of the repaires are more time then money, and when the leaks are fixed there's a good chance the problem will work with full vacuum. I've used a tube of silicon to fix couplers in spots not visable. I love my Benz 87 300D as there designed to work on and have found normal parts weren't any more expensive then GM.

 

This was good reading. How do you even know what parts are part of the vaccume system?

 

Thanks for all your help.