Is the white switch known to go bad?

I plugged the line going to the A/C controls. I have pulled vacuum with a mighty vac from the front of the car on the line going to the main reservoir. It holds vacuum. I pulled 10 and left it there for a few minutes. I also pulled the drivers door panel and pulled the vacuum lines off the master switch on both the green and red lines. Both of those lines hold good vacuum with the other one plugged. I also pulled vacuum on the line going from the engine bay to the master vacuum switch. No leaks there either.

Here is what is happening. When I run the car, turn it off and get out to lock it... Most of the vacuum is already bled off and only a couple of the locks operate. If I sit in the car and run the engine for a minute or so, lock the doors, shut off the engine and sit there upwards of 5 minutes, then unlock the doors... They all work. Over 10 minutes and it bleeds off.

Basically when the locks are open is when the vacuum is being bled off quick. Is this a symptom of the master vacuum switch? Or could it be any of the other lock actuators as well?

There used to be a "pinned" vacuum troubleshoot guide at the top of the page. But every since "PeachParts", it has disappeared?

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AJ

1985 300D (SOLD)

You have a vacuum leak, it could be anywhere in the central locking circuit.

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1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg

1984 300D TURBO 149K
PULL THE REAR RIGHT PANEL ONE BOLT REAR, CHECK WITH VACUUM TESTER,MAYBE THE GAS FLAP POD LEAKS, OR THE TRUNK LOCK POD, TAKE COVER OFF NEXT TO THE TRUNK LOCK TEST THE VACUUM POD,I HAD SLOW LEAK REPLACE AND OK AT THE GAS FLAP COVER AND TRUNK LOCK, THE DRIVER DOOR WHERE THE VACUUM HOSE GOES TO THE DOOR FRAME

Thanks Raymond... I was just wondering if the white master switch is a common failure point. It seems to be working ok and holds vacuum in certain positions.

I'm going to go get some golf tees and start pulling more panels.

I think you may be on to something with the gas flap. It seems like that and the trunk have a mind of their own.

It is a PITA running around constantly opening and closing things manually.

__________________
AJ

1985 300D (SOLD)

Everything works now. Vacuum is a good thing when it is available! It is nice to have all the vacuum lines hooked up under the hood.

The problem was in the drivers rear door vacuum actuator. It has a pin hole in the diaphragm. All the locks now work like they are supposed to and the thing holds vacuum for a long time. The car has been sitting for a few hours now and I went out and ran the locks through 5 times. No problem... I took apart the door lock actuator and found a pin hole along the long axis of the diaphragm. I'm going to try and patch that with an inner tube repair kit and see what happens. I'll order a new one if it does not work.

I also cleaned out all the door drains, lubed the door checks, lubed the window slides and installed new vapor barriers on all the doors while I was inspecting things.

I also did some checking under the dash and found 3 of the vacuum elements had torn diaphragms. I removed the bad ones, plugged the lines and safety wired "open" the necessary A/C controls so I can still run the air. It is getting hot down here.

Can you buy just the rubber diaphragms? Or do you have to buy the whole damn thing. It looks like they made them easy to remove, take apart and service, if needed.

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AJ

1985 300D (SOLD)

I've read that people do replace the diaphragms, I don't remember with what...bicycle inner tube comes to mind...but I don't think they sell new diaphragms.
Good job on tracking down the leak. Mine have all been in the little rubber boot that seals the shaft coming out of the top of the door actuator.

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1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now

I figure I may as well try to repair these things before I shell out a couple hundred for new elements.

I'm trying a product called skabs made by "Slime". I started with the door lock actuator and it actually worked! I cut the skabs into small strips and put them on each side of the rubber diaphragm. I have cycled the door lock actuator at least 100 times now and it has been sitting on my mighty vac for over 1 hour at 13 in. HG.

The door locks in my car work perfect now. So, I'm going to give it a go and see if it actually works in the car.

I am also working on one of the diaphragm's for the A/C. I had to use bigger pieces for a bigger hole, basically cutting them in half. I am still working with it. I'll post my results if it all works.

I'm impressed with the door lock actuator. My only concern is the heat down here. I'm wondering if the skabs will get all gooey and fall apart in a hot door in the middle of the summer? We'll see.

Here are some pics:

Skabs

Skabs installed on both sides of cut

Door lock actuator holding 13in. after many cycles

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AJ

1985 300D (SOLD)

Boy, I wish I had heard about the Skabs repair before buying two new actuators for my '81 300SD. The actuators themselves were fine; just had bad diaphragms.

As far as the front actuators go, I remember some of the threads say there are two types of actuators. The ones with single diaphragms cannot be repaired; however, there are two diaphragm actuators and they can be repaired easily. You might check to see which one you have. If you have the single, I would try the Skabs. Except that on the SD it is such a pain getting the actuators out of the dash, you would never want to try a repair that might not work and would cause you to pull it apart again.

Absolutely... I will be the guinea pig. I have repaired 3 actuators here in the past couple hours.

I found that the A/C actuators were still leaking after the repair. Turns out the seal was not good around the edge of the diaphragm. So, I pulled all the actuators back apart, cleaned the edges around all the diaphragm's with soap and water, applied a little bit of silicone grease to the edge's of the diaphragm and both sides of the housings and put them back together. No leaks now. I can pull over 15 in.hg. on everything with no leaks and multiple cycles. In the end I wound up putting a little bit of silicone grease around the edges of the skab's too. I figured this would make them slippery in case they decided to chafe on the inside of the housing or one of the springs.

I'm going to put 2 of the A/C diaphragm's and the one door lock actuator back in the car tomorrow and see how it goes. Now that I "know" where the leaks are (were), I'm not afraid to try a few things.

__________________
AJ

1985 300D (SOLD)

I have rubber boots available for sale for the exterior top on the rod of the door lock vacuum actuators. For body W123. This is less expensive than replacing the whole actuator for ~$20. send me a message.