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hydraulic strut rebuild

25K views 22 replies 14 participants last post by  LeftCoastGeek 
#1 ·
I recently had one on the rearh hydraulic shocks on my 300TE go out (leaking fluid from the shaft to seal point. So I removed it, and found that these shocks can be taken apart and one can get to the rubber seals and aluminum ring, etc, that seal shock and keep the fluid from leaking out.

I have looked everywhere on the internet and it seems like know one has ever thought to attempt rebuiling one of these, it seems that rebuilding might be something to consider due to the face that these seal shoudl be cheaper to obtain than to have to buy a new shock at about 400 dollars each.

These shocks are not that hard to take apart, when removed they are unpressurized unlike regular shocks so taking them apart does not pose a safety hazard like a regular shock would.

So since one can take these apart and get to the seals, why not make a rebuild kit for them. I guess everyone likes paying 1200 to fix a suspension, I personally would look for a more inexpesive fix, and since the shock is already broken, I cant make it any worse by taking it aparts, worth a try to fix, it looks fixable to me...

So I am wondering if anyone knows where to get these seals? Or has had these rebuilt or rebuilt them.
 
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#2 ·
hi, i havnt heard of a kit for these but im not that clued up on this area but if there isnt a kit why not think about buying a 'spares or repair shed'? you can pick one up that is a runner for less than £100 - if you compare that to the cost of replacing two front shocks and springs your already way above £100, no brainer to me?!

good luck with this though, im interested to know how you fix this so dont forget to post your solution please?
cheers
Ben
 
#3 ·
With 2 88TEs I'll be watching this thread with interest. I've certainly never heard of anyone rebuilding the cylinders. The bellows seals on the cylinders on both my cars are shot and hanging in pieces. I managed to find a tattered bit of bellows with a part number and even the bellows is not available from MBZ.
 
#4 ·
Now I have pictures to prove that these have to be rebuildable

My opinion is that if you can take something apart, you should be able to fix it.
 

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#5 ·
und mehr...

As for the rubber bellows, I too have looked for these and cannot find them, but I was thinking to use the bellows for the standard shocks as you can but them, or maybe from a w126, as I have a 560SEL which I have a set of extra shocks, I do not actually think the w126 has rubber bellows and the standard shocks but I need to check... But regardless, my point is that since the bellows are only to keep dirt and grime out, one could pontentially use any thing that is about the same shape and size and that has the elasticity that the original bellows has to protect the struts.

So I am just going to try to find something that I can use in place of the bellows, as the rubber bellows on both of my struts are destroyed.
 

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#7 ·
... and I think I would just need the two rubber o-rings, and the round rubber (green) flat ring to fix this... also maybe the metal ring on the top piston which resembles an engine piston ring, though after looking at the top piston when I got it apart, I do not think the ring or that piston plays too significant a role in sealing the strut as there are those seven holes in the piston which the washers when installed do not seem to completey seal the piston which I do not understand, but it seems to allow for a certain amout of fluid flow past the piston, making me think that the lower cylinder with its o-rings has the task of sealing the strut.
 
#8 ·
4-matic...

I think "they" are a bunch of evil automotive manufacturers who are allow conspiring to make everything unrepairable so people either have to buy new expensive parts or some just give up, and get rid of what really is a perfectly good car to go buy an expensive new car, we all need to rise up or something... this is unfair! :mad: :D
 
#10 ·
I went to Tacoma Hydraulic (A seal house) and found the exact o-rings and the scraper as that green ring is called. I have found that any seal house / hydraulic company that does seals and o-rings can provide you with pretty much any diameter and size o-ring and scraper you want. The o-rings were about 20 cents each, and the scraper is 6.00 each.

I replaced the o-rings and the scraper by prying the old ones out with a small screw drive and gently pressing the new ones in with my thumb. I then put everything back together and have run the car and so far nothing seems to be leaking. I still need to take it for a drive to see if it works. But so far so good.

I think if it were to still leak, my next idea is to get a slightly thicker scraper, I would assume that over time, the piston shaft might wear and so I think an oversized scraper would compensate for this.

I will post pictures soon.
 
#14 ·
I went to Tacoma Hydraulic (A seal house) and found the exact o-rings and the scraper as that green ring is called. I have found that any seal house / hydraulic company that does seals and o-rings can provide you with pretty much any diameter and size o-ring and scraper you want. The o-rings were about 20 cents each, and the scraper is 6.00 each.

I replaced the o-rings and the scraper by prying the old ones out with a small screw drive and gently pressing the new ones in with my thumb. I then put everything back together and have run the car and so far nothing seems to be leaking. I still need to take it for a drive to see if it works. But so far so good.

I think if it were to still leak, my next idea is to get a slightly thicker scraper, I would assume that over time, the piston shaft might wear and so I think an oversized scraper would compensate for this.

I will post pictures soon.
The wear in the metal is the problem.....you can continue to replace the seals to prevent leakage, but the piston wear compromises the performance of the assembly....
 
#11 ·
Hope this turns out to be helpful.
I needed to replace the hydraulic cylinders in my E320 cabriolet's top. Needless to say, the dealer wanted over $5000.00 for the parts alone. WOW! About twice that for the entire job. I thought I'd never have my top down again.
But...another enthusiast on Benzworld turned me on to this guy who is rebuilding them as I write @ $40.00 each. Nice.

mercedescylinders@sbcglobal.net
Dennis Ficken
16285 S. Chester
Olathe, Ks 66062

Best wishes, and goods luck!
David
 
#15 ·
Maybe this will help.
The hydraulic cylinders in my 95 E320 cabriolet top starting leaking. Thousands to replace......thousands. MB offers no repair/rebuilding whatsoever. Nothing.
And so, on Benzworld after my post, I was turned on to Dennis Ficken. mercedescylinders@sbcglobal.net
For me? Great news. $40.00 @ to completely rebuild them, one day turnaround and now they're better then new. Hopefully he can do yours as well, and inexpensively. Email him, check it out, and mention my name.
Good luck,
David Reisbord
 
#16 ·
In aircraft struts the piston rubs the bore making a minor step . The Teflon guide ring keeps the metal piston from making contact to the bore . Once the bore is worn the strut will never slide evenly .

The aircraft gear runs at 1500 - 2000 psi , so you might be
Ok
with the 3 -4 hundred psi in the MB struts .
 
#17 ·
A progress report. Per the above comment, the tubes indeed become stepped over time. But I've been working with a rebuilder of hydraulic actuators for construction equipement, and there's no reason why the tube can't be honed smooth. The shaft can even be polished if it's damaged. So I see no obstacles in restoring them. Pressure is considerably less than an aircraft strut, or even an automotive brake line. I hope to have one rebuilt in the next few days, will keep you posted.
 
#18 ·
Here's the outcome. No problem finding the o-ring and shaft seal, but the iron piston ring has to be reused. I had a rebuilder do the work, including honing the cylinders and polishing the shaft. One of my struts simply would not come apart, so I had to find a used one to replace it, which was then rebuilt. The boots I mentioned barely fit, you have to position them just so or they will bind. Total cost of machine work, labor, and parts was about $200 per side, not counting the cost of the replacement strut. Included in that price are new hoses, with swivel ends (since the fitting on the car was frozen solid). I'm not sure all this makes economic sense, unless you take the chance of skipping the machine work. But it does work, and it was a fun experiment.
 
#19 ·
I know this is reviving an 8 year old post/topic but I'm going to give this a shot with my 560SEL soon.

I've decided to rebuild the SLS system but just the hydraulic component (pump, lines, accumulators, shocks, & reservoir filter).

OP: Do you happen to know the physical dimensions of the o-rings and scraper ring for sourcing replacement parts?

I have some experience with hydraulic cylinders and tackling this rebuild should be fairly straightforward to me.

I may even do a write up.
 
#22 ·
Is that with aftermarket parts?
 
#23 ·
you might look up a motorcycle racing suspension service shop, I bet they have access to all sorts of custom seals and such. motorcycle shocks tend to be considerably more sophisticated then most car shocks and are regularlly rebuilt, both race bikes and high end road/offroad bikes, shocks by Ohlins and others.
 
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