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?
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.
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.
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.
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.
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.
orig.plate + mastic = orig.plate + epoxy = new plate + O.ring
two alternatives, user's choice.
Can't say much about older designs.
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.
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..... ;-)
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.