Airmatic Strut - Epoxy Fix - Page 2 - Mercedes-Benz Forum

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post #11 of 136 (permalink) Old 09-05-2009, 06:19 AM
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Mine look just like the ones with mastic at at Air-matic failed !! - MBWorld.org Forums - except, no cracks. From what I read on the forums, it is a DIY job with the special tool.

Warren

2013 S550

Formerly:
2010 S550
2005 S500 4-Matic
2000 S500
1978 450SL

Last edited by Skylaw; 09-05-2009 at 06:22 AM.
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post #12 of 136 (permalink) Old 07-23-2010, 07:58 PM
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airmatic epoxy fix documentation

Quote:
Originally Posted by S320L1999 View Post
Hello:

Does anyone know what happened to the guy that sealed his struts with Expoxy? All his video on youtube are no longer available.

Thanks
I'm back. The videos have been replaced by a pdf document - 1st doc attached "SUMMARY OF EPOXY FIX..." Hope it is more useful, allowing for quick review, printing, etc, which is more difficult with the videos.

Even though I prefer the Epoxy fix myself, for comparative purposes and as useful documentation, I have also posted two versions of the OFFICIAL WIS documentation relating to the fix-kit replacement procedure.

If you prefer NOT to do the epoxy fix, the FIX-KIT part number from MB is: A 220 320 25 38 for the W220 car without ABC (active body control) and without 4matic.

The fix-kit includes a new upper metal cap that includes an O-ring, and a new c-clip and brass valve, with yellow lubricant. you can see pictures at:
http://www.benzworld.org/forums/w220...ml#post3244659

If you decide to carry out the epoxy fix, you do NOT need the MB fix-kit.

REFILLING THE BELLOWS IS PROBABLY THE MOST IMPORTANT STEP AFTER DEALING WITH THE UPPER-PART OF THE STRUT WITH EITHER EPOXY OR THE FIX-KIT.

NOTE: of particular interest, read about the different alternatives that exist to REFILL the BELLOWS after having carried either the fix-kit or epoxy replacement.

I have received messages from users that have damaged their front struts from improper filling, which then require replacing them entirely. Actually, if you break, tear or perforate your bellow covers, these are sold online, and you can replace any bad bellow covers, without having to replace the whole strut. If you do this, please be sure to post a thread with your procedure and any advice.

Pls read all documentation and understand what and why you are doing stuff - if in doubt, come back, and ask here! It is important to understand that the bellow of the strut (inside the wheel wheel) has a cover with an accordion design with horizontal folds, and must be free of vertical creases or folds to ensure proper function.

If the bellow cover is damaged, this part can also be replaced, as replacement bellow covers are sold from MB and aftermarket. (not covered here).

Even though I inserted warnings in the documents, about being careful, this epoxy fix is very easy for DIY.

Don't be afraid.

Be sure to have read the full procedure, and that you have gathered all the tools and ingredients prior to starting. Also, be sure to be patient in removing, curing and testing the epoxy fix.

Lastly, in terms of tools, be sure NOT to use the one-leg jack that comes with your Benz - it is a VERY dangerous jack to use, especially for long periods, or when getting under the car, getting into the wheel well, etc.

You need to invest in TWO good pneumatic jacks, which should be about $30-$40 each at your local hardware shop, which have wide bases with wheels, and are very steady and reliable. The Epoxy fix also does not require that you remove the wheels.

Go for it, and good luck! Let us know how it went!

Regardless of the fix you decide to carry out as a DIY, I strongly recommend to read all 4 documents below prior to doing anything.

UPDATES: A few users have commented on the need to apply some sort of sealing tape/string for the brass-valve, which will sometimes leak slightly, either in the epoxy fix or the MB fix-kit, given that the brass-valve is a steel-on-steel joint. Have a look at the comments later on in this thread for more feedback and ideas.
Attached Files
File Type: pdf _SUMMARY OF EPOXY FIX ON AIRMATIC FRONT STRUT LEAK-v04.pdf (1.54 MB, 8674 views)
File Type: pdf _W220 AIRMATIC DOCUMENTATION.pdf (1.46 MB, 4939 views)
File Type: pdf _OFFICIAL WIS AIRMATIC FRONT TOP-SEAL REPLACEMENT PROCEDURE.pdf (1.30 MB, 6051 views)
File Type: pdf _OFFICAL MB REFILL BELLOW PROCEDURE.pdf (264.6 KB, 4685 views)

2002 S500 - W220.175

Last edited by robledoch; 08-31-2010 at 08:27 PM.
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post #13 of 136 (permalink) Old 07-24-2010, 01:12 PM
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There is a kit you can buy to fix the leak on top of the air matic shocks. Scraping out the old black epoxy and filling it back in will not fix this. The part that leaks is a half metal and rubber cap under the black epoxy and secured with a metal lock ring. The new kit has all new parts and fixes the leak on top. When down you do not have to fill the top with epoxy. The cap is the part that is leaking. I have done many of these. Good luck
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post #14 of 136 (permalink) Old 07-24-2010, 06:15 PM
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Epoxy is a good alternative

Quote:
Originally Posted by toddfather View Post
There is a kit you can buy to fix the leak on top of the air matic shocks. Scraping out the old black epoxy and filling it back in will not fix this. The part that leaks is a half metal and rubber cap under the black epoxy and secured with a metal lock ring. The new kit has all new parts and fixes the leak on top. When down you do not have to fill the top with epoxy. The cap is the part that is leaking. I have done many of these. Good luck
Yes, the kit, for about $150-200 per side, parts only, will work. Then you also need to consider getting a special tool (three legs) for $50-100 to push down and remove/replace the undelying plate, etc, etc.

The epoxy fix, at about $5 per side, is much, much easier, since it does not involve removing and replacing the original steel metal cap.

I also recommend, in either solution you decide to carry out, to invest in TWO good pneumatic car jacks, $30-40 each.

The original steel cap is PERFECTLY FINE, and it is impossible to develop any cracks given its thickness. The main problem is simply a design that used black mastic instead of an O-ring, to seal around it.

For this reason, the missing O-ring is NOT required to be fixed, since replacing the black mastic with epoxy fixes the faulty and cracking black mastic. Using a good epoxy (see doc in other post), the original black mastic specs are superceeded.

Whether one uses the fix-kit (a new top-plate with the new O-ring) or leaves the original plate and replaces the old mastic with new epoxy, the idea is to ensure that the strut doesn't leak, and both solutions achieve. this.

You decide how much money and effort to invest/spend.

By the way, the epoxy can always be removed, since it is soft to sanding or drilling, but otherwise provides an excellent seal if left alone. It withstands the heat and pressures for the engine and strut.

I have had this fix on my car for over 18 months, and everything is working perfectly. Pictures below.

In addition to the epoxy, I also spray painted with regular car paint to make it look nicer. I also decided not to reinforce the brass-valve as I indicate as an option in the fix doc attached above.

Contrary to other opinions on this forum, the black mastic's function is to seal the circumference of the upper metal cap on the upper part of the front strut. It is not there to support the brass valve.

The mastic is not there for any other purpose but to seal the upper metal cap - and if you replace it with good epoxy, you're as good as when the car rolled off the assembly line.
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2002 S500 - W220.175

Last edited by robledoch; 07-28-2010 at 08:25 AM.
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post #15 of 136 (permalink) Old 07-25-2010, 07:14 AM
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I appreciate your thorough documentation, and I am very happy that your epoxy solution has worked. I don't oppose an inexpensive solution if it is effective.

However, I stand by what I said in post #9. There can be cracks in the metal - especially when car predates the '02 model year. My '00 had an entirely different design of strut top, and indeed, it flexed and began to crack. The earlier design had stamped and raised concentric circles and a smaller seal. The newer design, which your '02 (and my '05) has, is flat and is made of much thicker metal than my '00 was.

Second, the actual seal is below the circlip, on the opposite side of the plate. The circlip is not the seal - it serves to hold the components together tightly, so that the seal presses against the metal mount tightly. It is when the seal itself, under the circlip, leaks, that problems begin.

The mastic is, according to MB techs who have done many of these repairs, a vibration damper that keeps the narrow neck of the valve from flexing and itself cracking. Some MB repair instructions have not even required replacement of the mastic, and some MB techs don't replace it. If the mastic were the actual seal, such a repair would be worthless. In fact, the older design strut tops/seals (with the stamped concentric circles) did not have the mastic at all when they came from the factory.

Your approach does indeed stop a leak that has occurred in the seal itself - after the leak point, which is the seal ring under (below) the circlip. Your suggestion of roughening of the metal surface to help hold the epoxy in place is a good one, and is likely what allows your solution to work for a decent amount of time.

I am not criticizing your approach - as I said in a different post, it's tough to argue against success. Yours is much less expensive, and it has worked (to date) for you for 18 months. But your theory of the function of the mastic is wrong, as is your assumption that leaks won't occur because of cracks in the metal (at least, of older models - and I saw them in my '00).

Thanks for documenting your effort. Good job!

Warren

2013 S550

Formerly:
2010 S550
2005 S500 4-Matic
2000 S500
1978 450SL

Last edited by Skylaw; 07-25-2010 at 07:25 AM.
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post #16 of 136 (permalink) Old 07-25-2010, 09:40 AM
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Quote:
Originally Posted by Skylaw View Post
I appreciate your thorough documentation, and I am very happy that your epoxy solution has worked. I don't oppose an inexpensive solution if it is effective.
Thx. How about making this a sticky, allowing fast and easy access to users looking for this very common problem?

Quote:
However, I stand by what I said in post #9. There can be cracks in the metal - especially when car predates the '02 model year. My '00 had an entirely different design of strut top, and indeed, it flexed and began to crack. The earlier design had stamped and raised concentric circles and a smaller seal. The newer design, which your '02 (and my '05) has, is flat and is made of much thicker metal than my '00 was.
Yes, I can see that if the upper metal cap is thinner, it can suffer from bending and cracking, and would need replacing, and not simply an epoxy refill. Having removed the mastic, it is definitely important for users to visually check the upper metal plate. In my picts, you can see that it is in perfect condition. Pre-'02 owners should let us know the condition of their upper plates.

Quote:
Second, the actual seal is below the circlip, on the opposite side of the plate. The circlip is not the seal - it serves to hold the components together tightly, so that the seal presses against the metal mount tightly.
Yes, I agree - the circlip (C-clip), is not a seal, it only holds the metal plate in place at the top of the strut.

Quote:
It is when the seal itself, under the circlip, leaks, that problems begin.
I would add that the upper strut metal plate does NOT have a seal, strictly speaking. It is not a matter of WHEN the metal cap will leak, it ALWAYS leaks. I tested this theory on my driver side strut which had perfect mastic and no leaks - once I removed the mastic, the strut was leaking via the plate. The problem is that no O-ring was called for to seal the original metal cap. This is where I indicate that the mastic is used to seal the strut ABOVE the metal cap - and problems occur when the mastic starts to crack, given the mastic's bad specs.

Quote:
The mastic is, according to MB techs who have done many of these repairs, a vibration damper that keeps the narrow neck of the valve from flexing and itself cracking.
Skylaw, this is where both of us need to agree to disagree. I hold that the mastic is not there to dampen vibrations for the brass valve. No brass valves have ever cracked, with or withour mastic or similar stuff to "hold" it.
Quote:
Some MB repair instructions have not even required replacement of the mastic, and some MB techs don't replace it. If the mastic were the actual seal, such a repair would be worthless. In fact, the older design strut tops/seals (with the stamped concentric circles) did not have the mastic at all when they came from the factory.
The fix-kit does not call for replacing the mastic, given that the metal plate is replaced with one that has an O-ring instead.

Summary:
orig.plate + mastic = orig.plate + epoxy = new plate + O.ring

two alternatives, user's choice.

Can't say much about older designs.

Quote:
Your approach does indeed stop a leak that has occurred in the seal itself - after the leak point, which is the seal ring under (below) the circlip. Your suggestion of roughening of the metal surface to help hold the epoxy in place is a good one, and is likely what allows your solution to work for a decent amount of time.
My approach is simply to replace cracked mastic whose function is to seal an original design which did not include a seal at the metal cap, but above it with the mastic. I am simply replacing a faulty piece of that original design: old mastic = new epoxy.

The fix-kit changes the fundamentals of the orignal design, to include an O-ring with the metal cap, and avoid having to seal above the metal cap. Hence the fix-kit doesn't call for mastic refill.

The end result, in both scenarios = air-tight strut.

Quote:
I am not criticizing your approach - as I said in a different post, it's tough to argue against success. Yours is much less expensive, and it has worked (to date) for you for 18 months. But your theory of the function of the mastic is wrong, as is your assumption that leaks won't occur because of cracks in the metal (at least, of older models - and I saw them in my '00).
I'll be sure to be back every six month-12 months to this thread, and keep you updated. If something happens sooner, I'll be sure to be back with any late-breaking news - but the epoxy appears to be better than ever, and will probably outlast other parts of the car..... ;-)
Quote:
Thanks for documenting your effort. Good job!
Thx. It is my way of giving back to the community with solid and easy-to-follow documentation, the sort I would love to have when dealing with a DIY fix.

2002 S500 - W220.175

Last edited by robledoch; 07-26-2010 at 06:54 AM.
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post #17 of 136 (permalink) Old 07-25-2010, 10:48 AM
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In fact I would like to add this thread to the W220 S-Class Owners Start Here sticky (it's called the Encyclopedia on BenzWorld and MBCA) - but I have to figure out how to add another post in the middle of the two lengthy ones on BW - they're both at their character limits. But you can look for it!

Warren

2013 S550

Formerly:
2010 S550
2005 S500 4-Matic
2000 S500
1978 450SL
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post #18 of 136 (permalink) Old 07-26-2010, 04:23 PM
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Quote:
Originally Posted by Skylaw View Post
In fact I would like to add this thread to the W220 S-Class Owners Start Here sticky (it's called the Encyclopedia on BenzWorld and MBCA) - but I have to figure out how to add another post in the middle of the two lengthy ones on BW - they're both at their character limits. But you can look for it!
Hello Skylaw, good to hear that this post will be a sticky to help future community members with such a common problem.
BTW, I have always posted the official MB fix-kit procedure side-by-side with my own epoxy fix. I have edited my post above to make this more obvious.

With regards to the other two links from the encyclopedia, a few comments:

Airmatic Strut Kit Install - MBWorld.org Forums
-- the fix-kit description is rather general, no pictures, etc, and a very weak procedure to refill the bellows - which is very important to do properly. In fact, I am thinking of beefing up this section in my own documentation.

Airmatic Questions!! - MBWorld.org Forums
-- a few key ideas that need fixing:
1) "Cracks forming in the mastic at the top of the front struts, indicating that a seal beneath the mastic may be leaking"
--cracking mastic is simply that, "cracking mastic", and a loss of the only seal that originally comes with the car. Cracking mastic does not mean that the upper cap has lost its seal and is starting to leak. The original upper metal cap has no seal, and will always leak - hence the mastic.
2) "opening the door does not cause the release".
--Actually, opening the door can cause the car to raise, even if the engine is off, and no key in the ignition. The document listed above, "W220 airmatic documentation" explains a lot of the functioning of the airmatic system, but here are a few key points:

An AIRmatic central reservoir for compressed air also enables the
vehicle level to be controlled when the engine is not running. In
addition the adjustment of the vehicle level is decoupled from the air
compressor.

Wake-up function (operating period approx. 1 minute)
The AIRmatic with ADS control module is "woken up" using the
remote control, door contact switches or trunk illumination switch in
order to check the current vehicle level for critical conditions (level
too low) and if necessary to raise the vehicle or lower it when
unloading.

etc, etc.



Another observation worth mentioning is the need to summarize all of the posts into one KEY document or thread or post - like a wiki. This avoids having to read tons and tons of posts that then require the user to use whatever experience or judgment to distill and decide how to move forward. This sort of editing would increase the value of your forum 1,000,000 times. at least.

2002 S500 - W220.175
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post #19 of 136 (permalink) Old 07-26-2010, 05:01 PM
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It might, but it would also tremendously increase the amount of time that I must devote to the forums. I don't have an infinite amount of time (or the inclination) to do that. To do it as you suggest would require a great deal of additional writing to knit the various members' contributions together. The document as it stands took considerable time - and no one had done it in the 8 years the W220 has existed (counting its 1999 European introduction).

From my standpoint, it's one more suggestion for how I can devote more of my time for unpaid work, so others won't have to read several threads, and think. Not a very attractive proposition, given the time I have already spent.

Except for the time required not working for me, it's a good suggestion. Perhaps you'd like to take it on.

Warren

2013 S550

Formerly:
2010 S550
2005 S500 4-Matic
2000 S500
1978 450SL

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post #20 of 136 (permalink) Old 07-26-2010, 08:20 PM
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we can all do the work.

Quote:
Originally Posted by Skylaw View Post
It might, but it would also tremendously increase the amount of time that I must devote to the forums. I don't have an infinite amount of time (or the inclination) to do that. To do it as you suggest would require a great deal of additional writing to knit the various members' contributions together. The document as it stands took considerable time - and no one had done it in the 8 years the W220 has existed (counting its 1999 European introduction).

From my standpoint, it's one more suggestion for how I can devote more of my time for unpaid work, so others won't have to read several threads, and think. Not a very attractive proposition, given the time I have already spent.

Except for the time required not working for me, it's a good suggestion. Perhaps you'd like to take it on.

Okay, I understand. I can only really devote time to document the problems that I experience, and give that back to the community.

How about having functionality on the forum that allows the readers/users to rate the individual comments - that could, over time help filter by relevance/rating. In essence, the community makes this sort or filtering among tons of messages easy.

Another thing would be developing some sort of classification scheme (searchable) similar to tags, that the authors or moderators can tick on, allowing to quickly find similar stuff. At present I think the site search could work a little better. I think that personalized miini-google can also be activated within the site only.

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