What causes the air springs to fail? Does the rubber degrade?
Would injection of rubber lubricant into the unit increase service life?
Just a thought.

 

I think not as there is nowhere in the air spring unit that the diaphragm slides on anything. Experience of owners on here is that the diaphragm suffers catastrophic failure, ( a big bang followed by the car dropping down), needing the diaphragm replacing, OR slow leakage from the rubber seal at the top of the unit. This seal ages and then allows air to lead slowly out. The air compressor is normally able to more than keep up with this leakage, indeed Jaguar themselves in their technical notes state that some leakage will always be present. Of course on a new car there won't be much leakage.

The shock, (or damper) part of the unit normally lasts almost for ever, but eventually the hydraulic seal will fail and let fluid leak out.

There are now a few rebuilders of these and other units fitted to Mercs etc. They take your old units in as exchange items. You pay a surcharge for this which is returned when your old units are assessed as OK.

 

Our 05 XJ8L has 120k on the original units, and we just replaced a catastrophic blowout of the front right with an Arnott AS-2888 . It sounded like rats fighting in the dash area as we were driving home, then suddenly BANG!...and the rats got quiet.

Yesterday I got in the car and just before starting it heard "HISSSSS" from the front left side (still original unit), and when I turned the car on the leak was just as fast as the compressor. Why? It was the air temp. That night was the coldest we have had since we got the Jag a month ago. It got just cold enough to separate the metal from the rubber seals.

I figured this out by trying to inject some fluid (I tried some power steering fluid with leak stop) in and around all the flanges on top. It had warmed up yesterday, so when I turned the car on again in the evening, it aired up fine and had no leaking or bubbles at all. Great!

So this morning, it was cold again (about 38 F), but the air leak had returned just as badly. When I started the car, you could see plenty of bubbles coming out around the urethane bushing flanged area. I think it may also come out around the outer flange too, but that was not as visible. Regardless, the leak returned in the cold. I shall keep checking it every evening and morning again to see if the fluid had done any good at all, while we wait for the next AS-2888 to arrive next week. At least we will have matching units again!

 

A good shop that is replacing the air diaphragm should use some sealant on the inside of the top seal whilst the diaphragm is removed. Of course they may already be doing this, who knows ! Certainly if you don't want any returns, it seems a prudent service action.

 

I got the Arnott AS-2888 installed last night (YEAH!). Everything is working today, but then wife got an air suspension fault on the dash. Anybody get that after replacing fronts with the Arnott? Is this typical? It might be coincidental and caused by the rears or something else. We'll see.

FYI, the leak stop (steering pump fluid) that I put in the flanges seemed to work for the areas it could seep into, but since the strut is installed at an angle, it was only able to do anything on the downhill side. I'm curious if it would be helpful if the strut was removed and set vertical with plenty of fluid in the flanges where it could seep down to the rubber.

 

Make sure the electrical connector at the top of the shock is seated correctly. If that doesn't fix it - Contact Arnott Tech Support Mon-Fri - 800-251-8993 or 321-868-3016 or email info@arnottinc.com