Driver Door CLUNK in 300E
 

My 87 300E has developed a loud CLUNK when opening and closing the door, I took off the door panel and tightened a loose 10mm bolt that is towards the front and it got a lot better and almost normal, now the clunk is back, before I go tearing into it again, ( i hate working in that small space) can anyone tell me what to look for or any short cuts ? Thanks in advance

Sounds like you need a new door check.
You may be able to salvage it by re-greasing.

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1IY0V9AYZ1M219SS7U&year=1988&make=MB&model=300-E-002&category=O&part=Door+Check

door check.

you'll need to remove the unit completely to regrease it and that may not work either. there are two large ball bearings which provide a detent at door open and closed, they wear a groove in the casing and can jam at inopportune moments, I had to rush to the supermarket once to assist my wife who couldn't get the drivers door shut.

if this happens, and its your lucky day, a firm shove will release the bearing and close the door. beware, this will work one time only so don't get cocky and think you've fixed it. i did and opened the door again to see if it worked. had to strip off the door panel and remove the door check in the car park. not a good look.

Don't waste your time trying to re-grease..... it likely won't work... just spend the 20 dollars for a door check... there's a good chance when you take off the panel, the brittle plastic panel holders may separate from the panel.....

...when you put it together apply strong glue to the backs...shut the door...and keep it shut for 12 hours....

The entire door check procedure should take you less than an hour to replace....