Vacuum Door Lock Actuater
 

I found a problem with my rear passanger door lock actuater, it does not go up (perhaps some viagra would help :D ). Anyway, I need to replace it. Any ideas on the best place to purchase this puppy or can they be rebuilt?

The 84 might be rebuidable, but Fastlane (right here on this website) has a good price. I got one here a while back.

Take a look at:..............
 

http://www.peachparts.com/shopforum/diesel-discussion/160546-vacuum-door-lock-actuater.html
were the parts blow-up graphics are great.
Your part is at:
http://www.performanceproducts4benz.com/productpage.aspx?pid=102038 for just over $30. Even if you don't buy theirs, this should give you part names and an idea of what prices are like.

The 84 door element is not rebuildable. Go to fastlane for it.

The page for elements

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1V70TH4C51V70TH93M&year=1984&make=MB&model=300-DT-001&category=O&part=Vacuum+Element

Your unit

http://catalog.eautopartscatalog.com/mercedesshop/sophio/quote.jsp?clientid=catalog.mercedesshop&cookieid=1V70TH4C51V70TH93M&baseurl=http://catalog.peachparts.com/&partner=mercedesshop&year=1984&product=O4010-44438&application=000023767

Dave

Performance Analysis in TN is a good source for the vacuum parts, 865-482-9175 and other parts such as ACC servo's

mmenigma -

When I got my 82 300D last July, I found all three vac elements had failed with the dreaded torn shaft-to-housing sealing boot. Faced with a $120 bill for new elements, I developed a technique to repair them. So far, all three repairs have have held for a year.

If you're willing to let me have a crack at it, I'll repair yours (assuming of course you have this failure mode), document the technique with photos and share it with everyone.

PM me if interested.

Bob
'82 300D (with working locks)

Bob, Tell us something about your " technique "...
 

I’m guessing it repairs the diaphragms of the 3 door elements [with their 4 diaphragms each]. A lot of us on this FORUM are pretty good DIYers and I'm now doing much of the repairs on 3 of these vintage MBZs and although not yet, I'm sure I will face the same decision you did when you were motivated to develop your "technique" ! I could probably dream up my own workable repair but sharing ideas I thinks is the best thing about this FORUM for I believe it improves the quality of DIY fixes... e.g. maybe I might have a seemingly small idea that significantly improves upon your "technique".

I think I have better "tweaking" ideas than I do original ideas!

Best regards,
Sam

Actually, these should be the newer style "single diaphragm" actuators. A single diaghpram separates the housing into lock and unlock chambers. The housings and diaphragms are very durable. The weak spot is the rubber boot that seals the unlock chamber where the rod passes thru the chamber wall at the top. They actually look like a tiny CV joint boot.

These boots dry out and crack, and once that happens the unlock chamber is no longer sealed and the door will lock but not unlock. The boots are not replaceable. Any repair needs to completely seal the crack, but leave the boot very flexible and maintain its full range of motion.

Much easier to explain with photos

Bob, You did originally say...
 

" ...the dreaded torn shaft-to-housing sealing boot." but I missed it. Now I better understand the mode of failure. Actually our '80 300D had a similar failure in the boot on the trunk lid lock. I was not tempted to try a "fix" on it so I think it cost ~$32 new to replace.

So what product do you use to affect a repair of the rubber " boot " that allows the " full range of motion " ?

I'm tired of throwing part$ at these car$... especially when it's a piece of plastic and only available from the dealer's parts counter !

Sam

That's exactly the problem with mine. I can see the crack and need to repair it. I tried a quick fix, electrical tape and it worked but would not stay on. Perhaps rubber cement or a very sticky, thin, flexible tape.

Get some neoprene wetsuit cement and some silicone grease from a dive shop. For the procedure below use a q-tip as an applicator, but use a cheap off-brand, since you don't want a lot of cotton getting in your way.

1) clean the dust and crud from the boot and find the crack. Use a solvent like mineral spirits
2) apply some wetsuit cement to the edges of the crack, then move the actuator arm to the point in it's travel that keeps the crack closed
3) apply a thin layer of wetsuit cement to the entire outside surface of the boot, making a thin 'skin' over the entire outside. Let cure for 4 hours
4) repeat 3) to make a second skin
5) repeat 3) to make a third skin and let cure for 24 hours
6) The last skin will still be tacky and that's no good because the boot would stick to itself in the lock position, so take a small dab of silicone grease and apply it all over the outside of the boot. this will neutralize the tacky surface

done

Bob, An ingenious technique… good on ya!
 

Now, let me throw in a suggestion or two and a precaution to boot…
I wouldn't be tempted to “ clean ” the old rubber boot with Armoural for I think it leaves the rubber surface such that your wetsuit cement might not bond to the old rubber very well. I would use a weak solution of dish detergent and work it very carefully with a very soft brush [ if brush at all ] and then make sure all the soap residue is flushed off. A little rubbing alcohol would help you do the final cleanup and carry away the water.

Then let it thoroughly dry before starting with the gluing and special coats of wetsuit cement. Make sure you get the moisture out of the inside of the boot too. A hair dryer might help here. Your idea of using

That special wetsuit cement is not cheap... ~$7 :
http://www.sportsbasement.com/jump.jsp?itemType=PRODUCT&itemID=4570 but neither of these vacuum elements.
I figure $7 worth cement could potentially repair several thou$and dollars of such parts... boots as well as the diaphragms !

Great contribution to the THREAD Bob!
Best regards,
Sam

Armor-all? Where did that come from? Mineral spirits is what I used. It must evaporate and leave no residue behind.

My tube of wetsuit cement was $4.99. Silicone grease $2. You can easily do this repair 50 times for $7....

I toyed around with the idea to sandwich a postage stamp sized piece of latex cut from a rubber glove in between the layers of cement, but my first 3 tries worked so well without it I just dropped it.

Bob

Bob - " Armoural " or " Armor-all ", a MBZ mechanic...
 

friend taught me to do general preventive maintenance on these vacuum diaphragms and rubber boots using the Armoural and I'm sure it works to extend the useful life of these synthetics by keeping them more soft and pliable... that is if one doesn't get too carried away and vigorously work or flex these old parts. I could see your neoprene based cement being used as soon as you detect any cracking of diaphragms or rubber boots on the shafts... and if so I would want to make a concerted effort to clean off the surfaces very well before applying the special cement layers. The soap/water and then alcohol and finally drying should do the trick.

Regardless, your use of the neoprene wetsuit cement is key to this unique repair technique and it was GOOD that you documented this technique and put into the archives of this MercedesShop forum WebSite.

Best regards,
Sam

OK, understand now. My perception of people's opinion of Armor-all is almost universally bad, so I won't use it.

The silicone grease is really important. I almost lost one of the pods because the boot stuck to itself in a giant sticky, congealed mess. A little heat unstuck it enough to be usable and the grease ended any thoughts it might have had about sticking again.