d6lc

Looking for some input and feedback from the guys who have already gone through this.
I'm working through fixing my 'new to me' 2007 S8. I've had it a few weeks and the front end both sides dropped within 48 hrs when I picked it up.

When I took it apart the LHS was the original strut (with 96k), yet to my surprise the RHS was an Arnott replacement with a build date of 11/15.

I decided to replace the OE strut with another Arnott as I thought that maybe the issue, and hoped the Arnott already fitted was good.

So fitted the new Arnott on the LHS yesterday, and refitted the RHS 'old' Arnott. 24 hrs in and the new front has dropped 3-5mm and the 'old' Arnott has dropped around 15mm. So I guess my hope that the dropping front was due to the original strut, is not the case.

According to the info, I got with the car, the compressor, relay and valve block has already been replaced, in he last 18 months/30k mikes. I've sprayed down the 'old' Arnott and can't see any leaks. I plan to pull out the fender cover and spray down the valve block to test that.

My presumption, was that both of my front struts were leaking, and it's not the valve block as the 'new' Arnott is staying pumped up.

Any feedback, ideas?

blazej01

If I was you I would check the air spring while it is sitting on all 4 wheels on ramps. I could not find a leak on my car while in the air. Once I whent up on ramps I could spot a leak.

MP4.2+6.0

Sounds like it is the Arnott to me. The side that drops first or more is the bad one. Need to replace already swapped out Arnott's is easily in the double digit percentages from my informal reading of posts over the years. Some owners have run three of four OE struts past 250K, so I would not assume it must be the remaining OE one that is failed when a new leak issue appears. My own sense of posts is to assume the opposite--that the rebuilt ones are the ones more likely to go again. Same with the other brands too; not just an Arnott thing. On yours, the greater drop on the Arnott side tells you it is that one; the other side still drops some due two added weight bearing down on it, and weight transfer across the sway bar given their design principles. Finally, when my one front gave out, I found no leak whatsoever from thorough soaping--struts or valve block. Thus, that diagnostic is worth trying, but hit and miss. A fair number of owners have reported both ways too--works on some, not on others.

d6lc

Thank you for the response. I don't have the details of the first Arnott shock being fitted. However checking the build date on the Arnott vs my carfax would suggest the original shock went out around 55-60k miles and the Arnott has 35-40k on it.

I'm disappointed that it's lasted 2 yrs/35k at best, as I don't know how long it has been leaking. I had Arnott struts front and rear on my wife's previous GL450 and sold that with 40k miles and no issues.

I just checked it again and the RHS has dropped 22mm in 36 hrs and the new LHS has dropped 10mm, as you suggest the LHS drop is more than likely due to the sway bar. Whilst checking the car out I should have discounted the sways to be sure.