Success!!
 

I pulled all of my door panels this afternoon and found the culprit in my ailing central locking system! The driver's side rear door had a torn diaphragm on the vacuum actuator. Replaced it with one I've had sitting around from a parts car, and now they work like a charm! I'll have to try again in a few hours, to see if it holds vacuum over time. :D

Mike

Congrats ! I know the feeling; last week I fixed my central locking system. I thought it was doomed, and it was only he diaphragm in the fuel door, and a misaligned door. The drivers door lock wouldn’t always move the vacuum valve enough. At any rate they work, and have held vacuum for more than 48 hours. I can also get around 10 locks & unlocks.

Now I will attempt the vacuum line replacement for the A/C & Heater system.
Wish me luck !
Robert

Good job Mike.

I bet the upper diaphram was the one with the leak.

Congrats ! I know the feeling; last week I fixed my central locking system. I thought it was doomed, and it was only he diaphragm in the fuel door, and a misaligned door. The drivers door lock wouldn’t always move the vacuum valve enough. At any rate they work, and have held vacuum for more than 48 hours. I can also get around 10 locks & unlocks.

Now I will attempt the vacuum line replacement for the A/C & Heater system.
Wish me luck !
Robert

Good Job
 

Congrats Mike,

I did mine a couple of weeks ago, passenger door.

Now the locks slam shut with authority.

Nice feeling, huh.

JCD

Question on the locking system...

Mine won't lock the doors but once all doors are in the locked position the master will unlock them. This is without the engine running. Do you think this could be a bad valve in one fo the doors that is causing it to not lock? The unlock cycle is very slow by the way as it just kind of eases the door locks up.

Thnaks for your feedback.

It sounds like you have a bad diaphragm on one of the doors. One way to check to see what door it might be is to start the engine, roll down all of the windows, and lock the doors with the drivers door. See what door hangs up. Then with the engine still running, pull to unlock on each of the other doors (not the drivers door) The lock that you can easily pull up on is likely the culprit. I have used this method with success. Once you have narrowed down what door it is, then proceed to removing the door panel. I must say that I have become quite proficient with removing them. I can usually remove a panel in less than a minute. Good Luck ! Let me know what you find.

Robert

The vacuum locking system has "two sides" to it, a lock and an unlock. Sounds like you have a leak in the lock side of the system. I had the same deal in my 1977 300D, so your symptom is not unique.

The fix is the same, probably a bad diaphram.

JCD

Thanks Guys,
I'll give the door locks the test. I assume the trunk lock could also be the culprit here? When I try to lock the doors from the inside with the driver's lock in the up position the door locks do not want to go down, in fact I am not sure I can push them down.

One follow up question, I can peel my door panels off pretty fast too except for the plastic cups where the handles are inset into the inside of the door. Mine do not appear to have any particular type of fastener i.e. a screw that is accessable. Do these just pop loose from the backside and if so how do you remove them without breaking them. I have been fearful of applying too much pressure with a screwdriver or anything as they probably cost $30.00 each from my local dealer...;-) This is a 115 body.

You can easily pry the black plastic trim off with a razor knife or x-acto knife...just carefully stick the blade between the front of the plastic piece, and the chrome trim, and pry it away. It's just a snap-fit. Once the front snaps out, you can slide it off the end of the handle. Careful--don't cut the trim or yourself! :) It's a pretty tough little piece of plastic...they are harder to damage than you might think. Actually, I have a few spares that look pretty good if any of yours are damaged already.

With the driver's lock UP, the others SHOULD be very hard to depress, if not impossible...That means the vacuum is holding well. If one of them is easy, then that's probably a bad unit. The trunk and/or gas door elements are likely candidates for being bad, because they are more "exposed" to the weather/heat/dirt/etc.

Mike

Thanks Mike.
I tried the test and sure enough the "lock" side appears to be in one fo the non-door units. I'll have to play a little more. The unlock seems to work pretty good albeit a little slow. Probably one of the non-door locks as well.

Viva La Vacuum.....
 

Mike;

Congrats on the vacuum repair.

I have to tackle my Climate Control vacuum. Seem like all the elements for the defroster, center vents and leg vents do not function as they should. The defroster is always open, the leg vents are always closed, and not enough cool air comes out of the center vent (cause it all goes out the defroster vents). I know this is not unique, but a little frustration in mid summer and mid winter.

Has anyone had any luck with this :http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=1832833100 . It looks like this guy is always selling this manual. Are there other manuals that address the vacuum system?

I am thinking about doing my own vacuum repairs too. Glad to hear that it can be done.

l8r,
James

I have the manual as well
 

You can get it directly from the his website, versus the auction. Kent's a good guy and the manual is a good overview.

JCD