Different from the 116 / 123 chassis and more difficult to troubleshoot
What's wrong with my Mercedes?
When troubleshooting your vacuum system you must know where the hoses and lines go
If the hoses are leaking or are not hooked up properly a number of problems could occur.
Pump mechanisms breaking apart and piston bolt failures
Common concern on 1980 to 1985 Mercedes Diesel 240D, 300D, 300CD, 300TD
Double check for damage and use a product to scare them away
Look for the cause in the drive mechanism