Most Common W123 Vacuum Leak Sources?
 

Just curious as I am sourcing vacuum leaks on a '83 300D -what are the most common vacuum leak sources/parts on a w123? Members, cast your votes! Thank you!

The vacuum elbows under the hood (or anywhere else), the connection at the reservoir, the recirc. flap actuator, the fuel door actuator and master vacuum switch.

Door locks.

For me, the fuel door lock (I've replaced mine twice).

I second that, I had problems with those in two of three 300Ds.

The first few years after we bought the car, the biggest vacuum leak was the shop sucking my wallet dry :eek:. I didn`t understand the system, so kept taking it back to fix the constant, hard shifts, door locks not working or eng not shutting off.

I think it was a easy money maker for them, I drop it off, they Vacuum my wallet.:mad:

Once I found out how the Vacuum system works, piece of cake. hello mity-Vac.

The only vac problem the past 5 yrs has been the R/R door actuator. replaced that, and it`s been smooth sailing.

Now, what do I do with all this extra money? :) ;).

Charlie

Vacuum items that are either exposed to heat (engine bay connectors come to mind) or have diaphragms (central lock actuators come to mind).

Surprisingly, the connectors that reside under the carpet and route vacuum for the central locking are intact and soft.

So how do you get at the fuel door actuator?
 

I am curious what the best way is to get at the fuel door lock on an 85 300TDT?

It's behind the first aid kit door.

HIS POST IS ROGUE T PROTECTED!

There are a couple of diagrams on this forum that can give you a good idea on how to repair it.

I narrowed down my door leak to the vacuum pod in the front right passenger door lock. I have it pulled out and the little rubber on the top of the module ruptured and I couldn't find anything to replace it with.

So I bought a whole new one :( oh well.

You can glue the finger of a nitrile glove over it to seal the tear, but it doesn't last as long as the original diaphragm. Bosch sells replacement diaphragms. Someone will probably post where you can get them.

EDIT: Here's a pic of what I mean:
http://i204.photobucket.com/albums/b...ctuatorfix.jpg

Eh it's whatever at this point. I have a whole new one coming tomorrow anyway. I can hold on to the old one and use it in case another one breaks.

If someone posts a link to where there's a diaphragm I'll be returning my brand new one to phil!

diaphragm source anyone? Phil? I am certain that Phil can source the diaphragm repair kits -

I sealed one of mine with a "skab" (inner tube repair patch). It had a small hole in it. That was back in March I think. The locks still work great and the car will hold vacuum indefinitely.

While inside my driver rear door to work on non operative window, I noticed that the diaphragm had a tiny tear so I removed and very carefully applied some black "tool dip" formula to seal crack -should be interesting to see if I can pull vacuum after this repair. Actuator would vacuum in down position as it self sealed its crack but lost vacuum going up as diaphragm crack was exposed - I did find the guy on the MBCA site who makes the diaphragms and emailed him to see how much he charges for replacements -thanks!