For some time I've known our front air spring/shock has had a leak, but since it only seems to be a problem when temperatures are below about 43 degrees F, I've just lived with it. However, now that temps are below 43 again I decided to do a little detective work. I sprayed soapy water on the air fittings on top of the air spring and watched for bubbles. The air hose fitting and pressure sensor are good, the CATS solenoid is good, but air is leaking from beneath a red rubber seal in the top mount of the air spring. See the blue arrows in the photo below:




The cutaway diagram in the dealer training manual doesn't show the CATS solenoid and appears to be slightly different from the actual units in our X350, so I assume it's a generic diagram from either Wabco or Bilstein.

Does anyone have experience repairing this seal, or at least disassembling the air spring to access the seal?

I realize that I may ultimately need a rebuilt air spring/shock, but I'd at least like to try repairing this one if possible.

Thanks in advance for any info or ideas.

Cheers,

Don

 

Hi Don

I am sure you know this but here goes:

The leak is a classic leaking strut and requires replacement which can be done in

about 1.5 hours as long as the ?T40 bolt at the bottom is not gummed up with Loctite.

AFIK a leaking strut is not repairable but it would be interesting to dismantle a failed

strut to identify where and how the leak has ocurred.

You never know but once this has been done there may be a way to repair it.

BTW Is that the CATS solenoid shown in your pic (with the red tip)?

Does it just pull out?

Cheers

 

Hi meirion1,

Thanks for your reply. That's the answer I expected. Everyone I know of who has reported a leaking strut has just replaced it. But since this seems to be leaking past the top seal, and not from the air bladder, I'm wondering if there may be something I can do to extend the life of this shock. I'm considering options.


The black plastic component with the red tip does just pull out when you squeeze the two tabs on its sides. I think it is just the CATS harness electrical connector. The CATS solenoid is probably the metal hex-headed component mounted in the top of the shock. It has a deep cylindrical well with two male pin-style electrical contacts in the bottom that mate with the female contacts in the red tip of the plastic connector. I tried loosening the CATS solenoid with a 17mm socket but the entire top plate of the shock wants to turn, and when it does, the air leaking past that red rubber seal increases.

More to come!

Thanks,

Don

 

Just found mine leaking today as well. Mine is blowing out lots of air from the hole in which the arrow is pointing.

Is this a bad shock or is this where it dumps air to lower the vehicle?
I was thinking maybe there is an issue with the upper level switch perhaps and it is just dumping all air thinking it is too high?

 

No, air should never escape from the shocks. The system purge and lowering is controlled through the exhaust valve in the pump.

 

Just because I happened to be looking this up right now (to go buy one). Size is T60 for the lower shock bolt.

 

Hi Mooman333,

mhamilton is right - the exhaust valve is part of the air compressor assembly, and I don't believe air should ever escape from any part of the air spring/shock.

I may try to partially disassemble the unit to see if I can tell what is going on, but I may first try working some sort of sealant as deeply as possibly under the red seal to see if I can seal the leak to extend the life of this air shock.

Cheers,

Don

 

DonB - let us know how you make out. I'm having the same issue (thanks to our unusual cold weather) and would like to try this as well.

 

Will do, anindyam. I'm contemplating what type of sealant to try using and how to inject it as far as possible under the bottom edge of the seal.

I'm open to any suggestions for a sealant that can adhere well to both metal and rubber, and can withstand something in the range of 150psi.

Cheers,

Don

 

IMHO, sealing from the outside will be difficult to achieve due to the high pressures generated in the air spring from road movements. My technical notes of 2003.5 state a normal working pressure of between 7 and 9 bar, and full bump pressures up to 20 bar. That is an awful lot of pressure to resist ! However all is not lost when the spring unit drawing is carefully examined.

The photo is pointing to what is actually, (from the cutaway drawing), a rather large rubber sealing and possibly anti-vibration moulding, and the path for compressed air to exit to atmosphere around this seal is quite long, so the pressure at exit point may be able to be resisted with a suitable sealant. If it were me, I'd give it a go. After all, it will be cheaper than a new/rebuilt shock !

So I would fill that space with a robust silicone sealant, leaving the space for the shock switching connection. It may well work and even if a bit of air is still lost, it'll be less than before, so the compressor wont get so much use, and hopefully the fault messages will disappear.

All the above is theory, of course, it has to be tested in action !

 

Fraser,

Thanks for your encouragement! Your thoughts echo my own. The cutaway drawing in the manuals does not show the CATS solenoid, which makes me wonder if the drawing is generic, either from Wabco or Bilstein, and may differ somewhat from the actual units in the X350. I still assume the seal in question is not too dissimilar from the one depicted in the cutaways. My thinking is that if I can fabricate an injection nozzle that is either small in diameter or flat in cross-section, and bent at an angle near the end to clear the CATS solenloid, I will attempt to slide the tip deeply under the seal, toward the outer circumference of the metal top plate, and inject a strong sealant that will bond to both the rubber seal and the metal top plate. This may have a chance of reducing the leakage and extending the useful life of the shock.

It doesn't help that temps have dropped in to the low 30s (F). More to come.

Thanks again for your thoughts!

Cheers,

Don

 

I just went for a 5 mile drive on Sunday and in the last half mile got ASF then just approaching home vehicle too low. Quick check under the hood and I'm getting major air leak just like DonB describes on top of the front left strut

I'd love to find a quick fix until the weather turns warmer but looks like I may be out of luck

 

Didn't someone try to put in some two part epoxy all around the top seal?
High pressure, but the leak is probably fairly small, or it wouldn't pump up at all.

I did find an older post where tightening the big nut on top sometimes helps, one of the gurus. (tried it on mine, no luck).

Yes, too cold to put my new arnotts on


*on a side note, I rebuilt my air pump with the bagpipeandy kit just before the cold hit. My jag will drop on it's front haunches and looks like a low rider in front, but the rebuilt pump puts it back up under a minute. It used to cycle out over two minutes before the rebuild and it would sometimes take me 3 on/offs to get it to rise. It's a round about non-fix, but at least I can get going now!

 

I also used the kit to rebuild my air pump last winter and didn't have any problems until it got cold again this year. Now it's warmed up and things seem to be working fine. Seems to be an issue when the temp drops below the magic number of 40 degrees F.

 

What if you used a hypodermic syringe with cyanoacrylate glue? Hobby shops have higher-viscosity cyanoacrylate glue which might be advantageous.

 

Hi Gazoo2,

Thanks for your thoughts!

I do have low- medium- an high-viscosity cyanoacrylate for guitar work, but I'm still researching the best sealant options for bonding metal to rubber and also resisting high pressure. Here's one that looks interesting:

High Pressure Sealant - High Temperature Sealant | Copaltite


As to applying the sealant with a hypodermic, I don't think it will be possible to get any straight insertion tool very far under the edge of the seal due to the limited angle of approach. I've tried to work a thin, flexible pallette knife under the seal, but the seal seems to be very hard, either from age or compression between two metal components, or both. Since I'd like to make only one, successful, attempt to seal the leak, I'm currently assuming I will need to at least partially disassemble the shock in order to apply sealant deep enough under the seal to make a permanent, or at least long-term, repair.

Thanks again for your thoughts - I do need to look into the properties of cyanoacrylate to see if it is a suitable candidate.

Cheers,

Don

 

Have you considered using Loctite Black Max 380? It works well for sealing rubber to metal.

 

Hi Dave,

I have Loctite Superbonder 494 on my list of adhesives to research, but I'll add Black Max 380!

Thanks!

Don

 

Don,

Looking at the photo you posted at the top, the red rubber you call the red seal for the shock, is actually part of the Upper Shock Mount, and has nothing to do with the seal for the air shock. Why it is partly shown, I would just assume the Upper Shock Mount is about worn out and allowing the shock to move around a bit exposing the red rubber to be shown there. After awhile, it will more then likely be located somewhere else.

I had to replace my left rear airshock and believe me when I say, unless you have some real special tools, there will be no way to seal the shock your self. Thus the reason people just replace the shock with an Arnott reman.

This is just MHO.

Chuck
05/XJ8L

 

Hi Chuck,

The cutaway of the air spring/shock assembly from the Dealer Training Manual does not show the CATS solenoid, so I don't know how closely it matches the actual units in the X350. I assume it is a somewhat generic illustration from either Wabco or Bilstein.

In the cutaway, it appears to me that the Top Mount (Part 6) does contribute to the sealing of the upper end of the air spring, perhaps with the help of the circular object shown at the very top of the damper rod.

The lower end of the air bladder (Part 5, the "Rolling Bladder Membrane") is clamped to an inner, lower tube, and is otherwise self-sealing as it rolls upward on itself as the suspension compresses.

But the upper end of the bladder is open to the rather complex upper assembly of the spring/shock housing. The damper rod appears to be one path leaking air could take, but as Fraser has noted, there does appear to be a path for leakage around that top mount and seal, though the air path is rather long. Whether there is an additional seal below the top mount is difficult to determine from the illustration:




I do have a lot of less-common tools, and have been known to fabricate tools for specialized purposes, but if you can describe any specific types of tools you think may be required I would be grateful. I'm prepared to eventually concede that I need a rebuilt shock, but not before I make an attempt to determine the source of the leak and whether I can do anything to improve or resolve the issue.

And as far as Arnott's goes, they advertise that their rebuilt units use Goodyear air bladders. One of the things I intend to do is to contact Goodyear to see if those same bladders might be available to the DIY community.

Thanks for your contributions.

Cheers,

Don