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YOUR RESEARCHRebuild hydraulic cylinders 996 convertible
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very difficult
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Reported cause
Removing the white nylon piece proved to be very difficult.
I'm curious though about the operation of the ram and how this works - do I fill the cylinder with fluid just like I'm reloading it to reinstall, both banjo fittings submerged in hydraulic fluid and work the ram back and forth so both sides get full, then nut and bolt the fittings to seal the system?
Leading evidence: 'very difficult' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'very difficult' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Fill cylinder' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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I did open them and changed them myself as per how it was explained but I did notice that the seals were new not old so they must have changed the seals.
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For this I used a 3mm drill bit: Good idea but it is also doable without drilling when using two very small screwdivers
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I'm curious though about the operation of the ram and how this works - do I fill the cylinder with fluid just like I'm reloading it to reinstall, both banjo fittings submerged in hydraulic fluid and work the ram back and forth so both sides get full, then nut and bolt the fittings to seal the system?
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Suggestion
I should mention that I also filled these with fluid and capped off the end, that I had the snap ring still on, with nut + bolt and 2 copper washers to build the pressure better.
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I did open them and changed them myself as per how it was explained but I did notice that the seals were new not old so they must have changed the seals.
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Suggestion
Instead of using a blade to cut the old seals I squeezed them together to create a gap and then used side cutters to easily split them without having to worry about damaging the rod.
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Suggestion · Original poster
To get the white nylon scraper out to reveal the seal-ring I had to use compressed air, this is mentioned in the instructions in the kit, but how do you connect the air nozzle to the banjo fitting??
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Outcome without a verified action link
Well I used lots of electrical tape, put my hand over the joint as extra seal and it worked.
Did a search and did not find any useful information.
I found a youtube video on how to get to the cylinders so that they can be sent for refurbishment, about 220USD per cylinder.
I also found an O-ring rebuild kit on ebay for 22 bucks, so I opted for the rebuild kit.
the kit comes with instructions that are pretty OK but there are a couple of comments to those instructions that will make life easier for anyone trying this.
1. The cylinders are not meant to be repaired, I could not get the snap rings out without drilling. For this I used a 3mm drill bit. See pic.
2. To get the white nylon scraper out to reveal the seal-ring I had to use compressed air, this is mentioned in the instructions in the kit, but how do you connect the air nozzle to the banjo fitting?? Well I used lots of electrical tape, put my hand over the joint as extra seal and it worked. On one seal I had to warm it with an electrical heat gun, not the butane torch, and once I had it warm to the hand it popped right out with the compressed air. See pic for my class act tape joint, I had help holding the nozzle to the banjo fitting, ugly but it did the job.
3. Refilling the whole system took 4 fillings and the little 50$ porsche specific oil can you can buy did not do it, had to buy a bigger can of oil. Used a syringe and tubing kit from Ebay as well to do this.
4. Did not need to calibrate the top or do any other PIWIS work.
5. I taped the ram to avoid scuffing it when drilling and poking around to get the snap ring out. I can recommend to protect the ram.
6. The new o-rings are just stretched over the clevis and rolled over the white scraper ring
Hi Anders,
I also tried to purchase the rebuild kit on eBay, however I could only get the O-rings. They did not have the instructions anymore, which sounded a bit strange to me. Is there any chance you could share a copy or scan of these instructions?
Thanks!
For those looking to buy the rebuild service instead, I think I used
TopHydraulics or Cabriolet Hydraulics.
https://cabriolethydraulics.com/diy-porsche-carrera-911-hydraulic-ram-inspection-removal-instructions/
1. I could not get the snap rings out without drilling. For this I used a 3mm drill bit: Good idea but it is also doable without drilling when using two very small screwdivers
2. To get the white nylon scraper out to reveal the seal-ring I had to use compressed air: Much easier but a little messy to to with cylinder fluid: You suck out oil and then close the pipes with bolt+ screw+ 2 copper washers; then compress the cylinder.
3. Refilling the whole system: Steering wheel fluid (Pentosin 1405116 CHF 11S) worked for me and is cheaper
4. Did not need to calibrate the top :Yes, as long as you tape the left black bracket before removing the left cylinder.
5. I taped the ram to avoid scuffing it when drilling and poking around to get the snap ring out. I can recommend to protect the ram: A must
6. The new o-rings are just stretched over the clevis and rolled over the white scraper ring: I attach a PDF with some additional pictures
You can buy the O-rings separatly: Ref N4, 50 x 018 Metric Buna N-70 O-ring at :
www.theoringstore.com
(no affiliation)
Just finished doing this, here's a couple of notes on my experience.
I was not able to use two screw drivers to remove the lock rings so ended up drilling instead. Not too hard if you take it easy and make sure you don't drill too deep. My holes were a bit further down from the edge than shown in post #1. After that I used two small screw drivers to coerce the ring out of the sleeve.
I was not able to get the nylon scrapers out using compressed air. Tried heating it up but no luck. As described above, using fluid and a nut and bolt works well but is messy.
Instead of using a blade to cut the old seals I squeezed them together to create a gap and then used side cutters to easily split them without having to worry about damaging the rod.
Going through this whole process now, thank you all for this thread.
Got the snap rings out last night more easily than I'd expected, and then briefly tried the compressed air / electrical tape method to get the scraper out - that's going to be a hard no. I have a heat gun but didn't apply any heat, so much air was leaking through the ugly wad of tape that I didn't even bother. Then I put it aside for the night without trying the oil method, which I will this weekend.
I'm curious though about the operation of the ram and how this works - do I fill the cylinder with fluid just like I'm reloading it to reinstall, both banjo fittings submerged in hydraulic fluid and work the ram back and forth so both sides get full, then nut and bolt the fittings to seal the system? Once one scraper is out, though, doesn't the other end loose pressure?
I'll sort it, I'm just a little dense is all.
Thanks again for the thread and pictures!
I did not fill the cylinder before putting them back, I filled through the reservoir filler hole, 3-4 times and worked the top by hand slowly up and down a few times before trying to use the pump. you could probably fill the cylinder to some extent but I was worried it would get messy working with only 2 hands.
The black piece adjacent to the white scraper�is that the old �o-ring� and that piece gets removed/replaced with an o-ring or is the o-ring within the black piece?
I ordered a kit from eBay and the kit contains 4 O-rings total. I assume it's 2/cylinder. Does it matter where I place the O-rings in the cylinder or is placing them below the white scraper all that's needed?
Had to drill, had no luck with dental picks or any other pick. But it turns out removing the snap ring is the easy part. Removing the white nylon piece proved to be very difficult. Tried heat, tried compressed air, and the copper washer + bolt/nut trick. Still nothing. Oddly enough I feel I have enough pressure to remove the nylon piece on the blue marked line end of the hydraulic piston. But I am working on the red one first, and maybe my seal is just too toast for it to create enough pressure to blow out the internals on this end because all the fluid just bubbles out and leaks everywhere but doesn't push it out for me still.
Anyways I might give it another go tomorrow, but I think I'll drop it off at a hydraulic repair shop to have them blow it out for me. The other consideration is hooking it up to hydraulic pump on the car, but it seems as if I would probably be met with the same behavior, and this mentioned but not advised in the instructions due to safety.
Alright my father and I have figured it out. Successfully completed this job today. We used compressed air again, but we ditched the electrical tape set up as it didn't work or provide us enough pressure. This is what we did.
Items/tools used:
- original banjo bolt with thin copper washer ( remove the restrictor valve inside it (2.5 or 3mm allen I'm not sure which it was. Find a small allen that fits and remove it. (
Absolutely make sure you reinstall this restrictor when you're done
)).
- harbor freight air blower gun with rubber tip removed.
- some rubber fuel line.
- 1/4" DOT air line (widened with a leather-man to fit over the brass fitting on the harbor freight blower) put this inside the rubber tubing.
- Clamps
- electrical tape (but was not necessary)
Rig up something like this:
Once secured this did not leak one bit. So much better than electrical tape. And we were able to push out all 4 white nylon pieces with no heat needed. One of them gave me trouble still on one piston. The solution was to put the snap ring back in place and move to the other side of the piston where we had success. Once that seal was replaced it created the conditions where more pressure could be built up inside the cylinder (since it was not leaking out of BOTH ends anymore, only one) This knocked it out easy.
I should mention that I also filled these with fluid and capped off the end, that I had the snap ring still on, with nut + bolt and 2 copper washers to build the pressure better. Was messy but I found it necessary myself. I also found it surprising the end that you are trying to pop off is the end that you should hook up the air on. So if you're working on the red line end, you should hook it up there. Really glad this worked.
New o-rings 1 on each end of the cylinder. Each goes under the white nylon piece and then push it inside until you can place the snap ring in. You can go a little further than you want so be aware how far you push down. The top of the white nylon piece should be pretty much exactly where it was from before you removed it. I used the clevis to hammer it down.
Also pro-tip on the drilling. Pick yourself up some aluminum stop collars for your drill bits. These will save you from drilling too far. Used them on so many projects since I've got them.
https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1
Sorry to resurrect this old thread, but the link above doesn't work anymore and I can't seem to find these o-rings using the info given. Can anyone point me to where to buy them?
Thanks,
Rick L.
This kit is what I used successfully on 2, 996 cars so far. Hopefully these orings will out last the defective seal material used in the oem seals. There were no instructions included for me. But its kind of self explanatory if you're familiar with hydraulic cyls...
This thread is good instruction. It is a little difficult to get the small diameter cylinders apart, but keep trying and you'll get it,,, its only a c-clip. No need to drill anything for me.. Was probably easier for me then most diy types, since I've rebuilt shocks for decades and worked with hydraulic cyls, so am familiar with c-clips holding cyls together and how to remove them. My friend tried to do his with this kit and couldn't get them apart.
https://www.ebay.com/itm/27547158390...3ABFBMrurfocNh
Hello to All,
What I've learned studying the cylinders for my Mechanic is a few things to follow:
Cylinders are assembled crimped so they are not repairable,
To remove the locking clips just push the gland in and pick them out,
Cylinder comes with cup seals not o'rings so it's impossible to replace them unless You replace them with o'rings stretching over the ends,
And that is not a great idea because o'rings require a groove to seat on so they don't roll away when the rod moves in and out,
If You get to the point where You can replace the cup seal with o'rings You can not replace the piston seal and that can lead to
Leakage from one side to the other internally, That might not be an issue because of the locking position of the top when not in use
But You will have a weak cylinder that might cause You future trouble,
I saw an advertisement of a company that actually cuts the ends and replaces them with removable ends and lines so that can be repair in the future
But I can't find it in the web any more, I thought it was the only way to repair them and even then it might not be cost effective because the
Cylinder itself still be old and maybe worn for being aluminum...... I understand that I sound pessimistic but being a hydraulic tech is what I found,
And being a vintage Porsche Owner I understand the love for these cars.
Hello Everyone
I had the same issue and I sent out my cylinders for repair. I installed them when they came back and they were both leaking. The guy from Ebay was non responsive after the sale. I did open them and changed them myself as per how it was explained but I did notice that the seals were new not old so they must have changed the seals. I bought the seals in this tread and they are a bit different from the ones inside. Any idea why they still leaked even thought it had new seals? The shafts look nice and smooth no scratches or anything. I don't know if I am installing them wrong and that is why they are leaking? Any help would be greatly appreciated.
Well, the oem original polypropylene quad seals have a life of 5-20 years, depending on environment. At best its past their life span so all 996 will need rams rebuilt.
The o-ring replacements work well if a few precautions are observed.
Since we are stretching these o-rings over the ram hose ends, care must be taken to not over stretch them. The rams shaft hose end block edges should be lightly filed enough to round off any sharp edges that can put small cuts in o-ring when being pulled over the ram ends. Make sure to clean out the housing bores best as possible. Also the bore of the ram housing can not get scratched up when removing the clip, take care not to do this and o-rings should work well, they have worked for me for years and maybe hundreds of top cycles....
jmho
