w123 door lock actuator diaphragm

[Chad300tdt]

I just repaired the leak in the fuel door lock actuator on my 300CD. A new actuator is about $45 and they're difficult to find in stock anywhere.

I did some searching and found a part number for replacement diaphragms.

BOSCH part no. 3 340 522 025 - $1.92 each

These seem to be made better than the original diaphragms. I bought ten and with the cost of shipping, still paid less than one new actuator.

[Diesel911]

See Pic. Is the part that the Arrow points the part that you replaced?
A nice Fix.

If so I think that is what is wrong with My Door Vacuum Actuators except that there is parts crimped on above them that keep you from changing the Rubber Sleeve (diaphragm).

I have not gotten around to checking the Trunk of the Fuel Door Actuator (Pictured)

[Zacharias]

Originally Posted by Chad300tdt

BOSCH part no. 3 340 522 025 - $1.92 each

That's great info. I was told a while ago the diaphragms weren't available anymore. Glad to know they are.

[Adriel]

Originally Posted by Chad300tdt

I just repaired the leak in the fuel door lock actuator on my 300CD. A new actuator is about $45 and they're difficult to find in stock anywhere.

I did some searching and found a part number for replacement diaphragms.

BOSCH part no. 3 340 522 025 - $1.92 each

These seem to be made better than the original diaphragms. I bought ten and with the cost of shipping, still paid less than one new actuator.

How did you know you had a leak?

Ten?! Don't you think that is hoarding?

[daw_two]

Originally Posted by Adriel

How did you know you had a leak?

Ten?! Don't you think that is hoarding?

Ten is not hoarding!!! Chad owns 3 old diesel MBs. I own 4 (oops, 5, counting the Ponton). I probably could use ten in a week. My current project (in the garage) has multiple leaks, so, there goes 4 (maybe more). I'm hoping this same diaphragm is used on the trunk. What about the fuel door? If so, then that's 6 on every vehicle Chad owns and I own.

So, Chad. Is the diaphragm the same for the trunk, door locks, and fuel door?

[qwerty]

Originally Posted by Chad300tdt

I did some searching and found a part number for replacement diaphragms.

BOSCH part no. 3 340 522 025 - $1.92 each

The diaphragms are inside the actuator. Those parts are seals for the actuator rod.

[funola]

Originally Posted by qwerty

The diaphragms are inside the actuator. Those parts are seals for the actuator rod.

yep. It will not fix the leak. Time to go shopping again.

The diaphragm should be rectangular shaped.

[qwerty]

Originally Posted by funola

yep. It will not fix the leak.

If it's the shaft seal that's leaking, it should fix it.

A leaking diaphragm is another matter.

[charmalu]

I have pulled a bunch of the door actuators in the yards. 9 out of 10 are usually good. I don`t take a Mity vac with me, I pop off the door panel, remove 2 8mm screws, pull off the 2 vac lines and pop off the rod.

Suck on either one of the 2 vac lines and if they hold vac will, hold your tungue to it.

I took one apart to see how the innerds were put together. seems like the 2 halves were just snapped together and I pryed them apart. (Don`t have one in front of me at the moment) the rectangle diaphram had a small crack from years of use and heat etc...

the rubber piece the rod goes through at the top doesn`t seem to be replaceable because of the way the plastic piece the rod snaps into if fixed to it. don`t think it can be taken apart to be reused to work.
usually what I have seen is the rubber cracks at the rod.

Chad, this is a good tip and if they work for the trunk and fuel door, this is a good cheap DIY repair.


Charlie

[funola]

Yeah Charlie, now that you mention it, I do remember when I bought my first 300D T a long time ago, one of the very first thing I did was to fix the truck lock vacuum actuator. I remember taking the vacuum motor apart and used wet suit urethane repair adhesive (Aquaseal) on a punctured diaphragm. It is still working fine to this day.

[funola]

Originally Posted by funola

Yeah Charlie, now that you mention it, I do remember when I bought my first 300D T a long time ago, one of the very first thing I did was to fix the truck lock vacuum actuator. I remember taking the vacuum motor apart and used wet suit urethane repair adhesive (Aquaseal) on a punctured diaphragm. It is still working fine to this day.

My memory is not that good so I am not sure exactly what I did to fix the trunk lock actuator. Now that I think of it (again) I may have used epoxy to fix a leak at the vacuum barb. I tried searching for the post but couldn't find it. What ever I did fixed it and it is still working today.

[TheDon]

Originally Posted by charmalu

I have pulled a bunch of the door actuators in the yards. 9 out of 10 are usually good. I don`t take a Mity vac with me, I pop off the door panel, remove 2 8mm screws, pull off the 2 vac lines and pop off the rod.

Suck on either one of the 2 vac lines and if they hold vac will, hold your tungue to it.

I took one apart to see how the innerds were put together. seems like the 2 halves were just snapped together and I pryed them apart. (Don`t have one in front of me at the moment) the rectangle diaphram had a small crack from years of use and heat etc...

the rubber piece the rod goes through at the top doesn`t seem to be replaceable because of the way the plastic piece the rod snaps into if fixed to it. don`t think it can be taken apart to be reused to work.
usually what I have seen is the rubber cracks at the rod.

Chad, this is a good tip and if they work for the trunk and fuel door, this is a good cheap DIY repair.


Charlie

I brought my mity vac to the yard and the 300D I found all of the door lock diaphragms were bad. None would hold vac in either lock or unlock. What other models use the same door lock pods? just the 123?

[TheDon]

How do you replace them and where did you get them?

I had a dead door lock pod so I bore it open to see what's inside and where it was torn. Those diaphragms inside do not seem to be replaceable even if you cane crack theme open

[Chad300tdt]

Originally Posted by Diesel911

See Pic. Is the part that the Arrow points the part that you replaced?
A nice Fix.

If so I think that is what is wrong with My Door Vacuum Actuators except that there is parts crimped on above them that keep you from changing the Rubber Sleeve (diaphragm).

I have not gotten around to checking the Trunk of the Fuel Door Actuator (Pictured)

That's the piece.

Originally Posted by Adriel

How did you know you had a leak?

Ten?! Don't you think that is hoarding?

The car started having trouble shutting down and the door locks started to not work properly. I tested everything and it lead me to the fuel door actuator, which I just blocked off until the new pieces arrived.

Originally Posted by daw_two

Ten is not hoarding!!! Chad owns 3 old diesel MBs. I own 4 (oops, 5, counting the Ponton). I probably could use ten in a week. My current project (in the garage) has multiple leaks, so, there goes 4 (maybe more). I'm hoping this same diaphragm is used on the trunk. What about the fuel door? If so, then that's 6 on every vehicle Chad owns and I own.

So, Chad. Is the diaphragm the same for the trunk, door locks, and fuel door?

On my cars they are the same, but I've seen several styles of fuel door actuators and I've seen an older design of the door actuators in w123s as well.

My wagon uses 5 of these and the CD uses 3. I've already had a new actuator get leaks in this piece too, so I wanted to keep a few extra around. It's a quick and easy fix when you have the parts on hand.

Originally Posted by TheDon

How do you replace them and where did you get them?

I had a dead door lock pod so I bore it open to see what's inside and where it was torn. Those diaphragms inside do not seem to be replaceable even if you cane crack theme open

I bought them from Rock Auto. I've seen two styles of clamps on the rods. One is a large black plastic piece that the outer section pulls off the inner section. Pushing it down clamps it to the rod and locks the two parts together. The other is a white milky plastic piece that has a clip that pushes on from the side.

Both are removable and allow replacement of the seal/diaphragm. The new seal goes on easier with a bit of lube. I used 303.

[Adriel]

Originally Posted by daw_two

Ten is not hoarding!!! Chad owns 3 old diesel MBs. I own 4 (oops, 5, counting the Ponton). I probably could use ten in a week. My current project (in the garage) has multiple leaks, so, there goes 4 (maybe more). I'm hoping this same diaphragm is used on the trunk. What about the fuel door? If so, then that's 6 on every vehicle Chad owns and I own.

So, Chad. Is the diaphragm the same for the trunk, door locks, and fuel door?

Originally Posted by Chad300tdt

That's the piece.



The car started having trouble shutting down and the door locks started to not work properly. I tested everything and it lead me to the fuel door actuator, which I just blocked off until the new pieces arrived.



On my cars they are the same, but I've seen several styles of fuel door actuators and I've seen an older design of the door actuators in w123s as well.

My wagon uses 5 of these and the CD uses 3. I've already had a new actuator get leaks in this piece too, so I wanted to keep a few extra around. It's a quick and easy fix when you have the parts on hand.



I bought them from Rock Auto. I've seen two styles of clamps on the rods. One is a large black plastic piece that the outer section pulls off the inner section. Pushing it down clamps it to the rod and locks the two parts together. The other is a white milky plastic piece that has a clip that pushes on from the side.

Both are removable and allow replacement of the seal/diaphragm. The new seal goes on easier with a bit of lube. I used 303.

I am new to all this, so thank you all for your help!

I figured it be a vacuum leak, but wasn't sure how noticeable. Interesting it was so.

Where else are they used?

You bought these parts from Rock Auto? Or, the other part?

Thank you!
Adriel