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91 500SL 37k,90 300SE sold, 91 300E sold , 92 300E137k ,02 Kia Sedona ,I know..... its a Mini van.
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Discussion Starter #21
Most of those clips for the hydraulic lines go in different direction ,each cylinder has 2 lines,not sure if it matters which direction they go,did make a mental note!
 

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03 SL Kleemann, 97 SL320, 95 E320 cab, Tesla X, Ferrari 360, etc
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949 Posts
Klaus, I'm glad you brought this up. As for me this would be a great time and place to better understand the difference between the rod, cap, piston, and port seals. Thanks for any/all pictures that you believe to be of educational value.

Thanks in advance, Lynn
Lynn,

thanks for asking. As I have started explaining recently, there are four types of seals in the R129 cylinders (Top Hydraulics replaces and upgrades them all):

1) Rod seals. These are the ones that seal the piston rod from the rest of the cylinder. When they fail, you will see fluid coming out next to the shaft (rod). These are usually the first seals to fail in the cylinders.

2) Cap seals. These are just o-rings that seal the top cap of the cylinder from the housing. They are usually the last seals to fail.

3) Piston seals. They seal the input and output sections of the cylinders from each other, as the piston slides through the cylinder housing. Failing piston seals will cause internal leaks, which result in a pressure drop in your hydraulic system. Crumbling piston seals can block valves or pinholes inside the hydraulic system, and it can be difficult to diagnose a piston seal failure without testing several cylinders once you find that your top is moving slowly or not at all.

4) Port seals. They seal the hydraulic lines where they are pushed into the cylinders. Port seal failure is becoming more and more common as the R129s age. They have a special shape that makes them seal under pressure. O-rings wouldn't do the trick. They are secured by precisely machined brass rings (accuracy about 1/100 mm). DIY removal of the brass rings will almost certainly destroy the brass rings.

I am attaching below a picture of the cylinder shaft of an R129 tonneau cover lock cylinder with cap and cap seal, rod seal, and piston seal - before and after rebuild. This is actually one of forum member scottejupiter's parts. Note the shavings from the piston seal having swollen up and rubbed too hard on the cylinder walls. The next step would have been the piston seal crumbling apart.

One of the things on my to-do list is creating and posting some graphics or photos about the tiny, but important port seals.

Klaus

Top Hydraulics | Rebuilt and Upgraded Convertible Top Cylinders, Pumps, Hydraulic Lines - Top Hydraulics, Inc
 

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03 SL Kleemann, 97 SL320, 95 E320 cab, Tesla X, Ferrari 360, etc
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- reserving this post for cylinder cross section - to be posted shortly
 

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91 500SL 37k,90 300SE sold, 91 300E sold , 92 300E137k ,02 Kia Sedona ,I know..... its a Mini van.
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Discussion Starter #25 (Edited)
All packed up and off to Klaus! I'm sure glad I did this before my interior gets oily! that stuff is slick, highly recommend doing the work yourself,really not that hard ,I packed each cylinder in thick bubble wrap and lined the box with wrap also,lots of clear 2" tape,they all fit nicely protected in one of those 12 count wine boxes.
 

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91 500SL 37k,90 300SE sold, 91 300E sold , 92 300E137k ,02 Kia Sedona ,I know..... its a Mini van.
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8,119 Posts
Discussion Starter #26
Man that was fast! my rebuilt cylinders arrived today! now to find some time and install them,Thanks Klaus your the man!:D
 

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03 SL Kleemann, 97 SL320, 95 E320 cab, Tesla X, Ferrari 360, etc
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Well, timing worked out pretty well on your cylinders. The package arrived at Top Hydraulics on Friday afternoon, was return shipped on Saturday, and arrived at your place today, on Monday. :)

I took a bunch of photos of your seals, because this is an interesting case with your car being over 20 years old and the top never having been used before you bought the car this year. Will add those photos and some detailed comments to this thread soon. Just a hint: all cylinders would have failed in short order, and you actually avoided damage to the system by having all your seals upgraded now. Rod seals, piston seals and port seals clearly needed to be replaced.

Klaus

Top Hydraulics | Rebuilt and Upgraded Convertible Top Cylinders, Pumps, Hydraulic Lines - Top Hydraulics, Inc
 

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91 500SL 37k,90 300SE sold, 91 300E sold , 92 300E137k ,02 Kia Sedona ,I know..... its a Mini van.
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8,119 Posts
Discussion Starter #28
I had a feeling they were on their way out after I saw my 1st puddle!:D will start installing on Friday,my wife has me scheduled with Dr appointments most of the week,blah,blah,blah! thanks Klaus! nothing better than a working top with no issues!
 

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1999 SL500
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Velcro Question

Lowesguy,

In a picture on post #14 there appears to be a small piece of Velcro on the piston housing. I found this piece under my tonnue cover and could'nt figure out where it came from. What is it's purpose?
 

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91 500SL 37k,90 300SE sold, 91 300E sold , 92 300E137k ,02 Kia Sedona ,I know..... its a Mini van.
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8,119 Posts
Discussion Starter #31
Got the front ones in,about 1/2 hour, the new port seals are tight and its hard to push the lines in,but eventually they do,was wondering if its OK to leave the interior trim out to checks for leaks and operate the soft top?
I'm taking my time,rain next 3 days.
 

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03 SL Kleemann, 97 SL320, 95 E320 cab, Tesla X, Ferrari 360, etc
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Got the front ones in,about 1/2 hour, the new port seals are tight and its hard to push the lines in,but eventually they do,was wondering if its OK to leave the interior trim out to checks for leaks and operate the soft top?
I think I mentioned before that we make the port seals tighter than the originals, just in case folks have scratched their line fittings.

To answer your question, it is okay in your case to leave the trim off the windshield header or any other parts while checking for leaks when first cycling the top again. The only exception is the windshield header on model years '95-'02. If one were to leave the windshield header trim off on the latter, then the magnetic sensor mounted in the windshield header trim would not be registering, and either the top would not open or the controller would perceive an illogical situation and freeze up operation.

Klaus

Top Hydraulics | Rebuilt and Upgraded Convertible Top Cylinders, Pumps, Hydraulic Lines - Top Hydraulics, Inc
 

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91 500SL 37k,90 300SE sold, 91 300E sold , 92 300E137k ,02 Kia Sedona ,I know..... its a Mini van.
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8,119 Posts
Discussion Starter #33
Got the rear ones in all 4!, not hard at all,its a good thing they put the numbers on the locks and cylinders that correspond to the numbers on the lines, I forgot to mark them on dis-assembly !
 

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1996 SL500, 2000 E430
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Thanks for documenting this John - you can be sure I have bookmarked it!

I remember - when taking off my windshield header - I had a heck of a time prying that off for some reason - I guess after 17 years it liked its spot
 

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91 500SL 37k,90 300SE sold, 91 300E sold , 92 300E137k ,02 Kia Sedona ,I know..... its a Mini van.
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8,119 Posts
Discussion Starter #39
If anyone ever needs advice no problem ,just ask! will be putting the rest in today hopefully,the doc put me on some new meds!:eek: Remember I am not a professional mechanic,but I learned the art of reading and understanding things!haha,when I first got this car and read thru all the many post on soft top problems I fell off my stool! oh my God,how will I ever fix it myself??? so complicated,now looking back,no big deal,if I can do it you can too!
 
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