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D3 - Axles, Brakes, Suspension and Steering Brakes, Springs, shocks, steering racks, steering columns, suspension arms, wheel hubs etc. |
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#1
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Persistent knocking - diagnosis elusive
Hi Everyone
I have a 2005 A8 quattro SE 3.0 Tdi which is excellent in every aspect except for a persistent knock from I suspect the front suspension, or second guess the gearbox/engine mounts. I have had it checked out by two different specialists to no avail. If we were in the 1960’s or 1970’s it would be easy to diagnose as it sounds just like the exhaust knocking on bodywork when a strap has broken. It isn’t that though. The car is due an MOT which it will pass as there is no play, or worn parts, no air leaks and the suspension operates on all levels. There are no fault codes using VCDS either It has been suggested I have a “lazy” nearside front strut and replacing it might solve the issue. I think it is false economy changing one so I would change both sides and this leads me to the next dilemma. I can get Aerosus exchange “bags” at a fair price or Chinese manufactured ones also at a reasonable price, both with two-year guarantees. I am not adverse to buying either, I just want the best option so any positive comments would be appreciated. This with fitting, which I am not capable of doing myself (not a technician, no tools, no inclination and no self-confidence) means a budget of £1,000 and not a cast iron assurance that this will cure it. This makes it a gamble. I like my cars to be as they left the factory so I do not want upgrades, go faster spec, lowered, widened or stiffened anythings bolted on. I simply want this knock resolved. The alternative is to sell it and buy a D4, but I could conceivably spend another £7000 (minimum) and be faced with another set of elusive issues as with my buying power I would be looking at an eight-year-old car. So, the other man’s grass may not be any greener. What I am hoping for, is some advice, suggestions, recommendations or an offer to solve this. This cannot be the only D3 with this noise It is annoying because apart from this knocking, which resembles a persistent door-to-door salesperson hoping to sell me Betterware, Avon, or eternal salvation, the car is great. Any help would be appreciated
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Audi A8 2005 D3 3.0 Tdi quattro in Aurora Blue with cream sports seats, DAB Bose sound, 19” five spoke alloys, fingerprint technology and SatNav, wooden sports wheel and gearchange knob |
#2
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If the knocking is coming from a strut then its the damper portion of it, not the airbag, so changing the bags won't do anything. You'd need a good used strut assembly instead (Prestige have a D3 in at the mo I think).
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#3
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Thanks, that is great advice it never occurred to me to just change the strut and keep the rest. I will investigate....
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Audi A8 2005 D3 3.0 Tdi quattro in Aurora Blue with cream sports seats, DAB Bose sound, 19” five spoke alloys, fingerprint technology and SatNav, wooden sports wheel and gearchange knob |
#4
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I would have a look at the sway bar links.
I noticed massive decreases in clunking after changing these shortly after I changed the upper control arms. Unfortunately, the knocking came back so I was gearing up to check the struts. Until i looked under the car and found the sway bar link bolt in the bar had sheared off. Removing the sway bar completely (until the new one comes from germany) and taking the car for a drive eliminated all suspension noise on my car. Mike
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04 A8 - 4.2 Sport Indigo Leather Sports Seats - Sports wheel - Sports Air Suspension Auto Boot - Double Glazing - AMI - Solar roof TV - Bose - Voice Control - TPMS - AFS- TINT Power Blind, Fingerprint - Light package (in and out) Retrofits: OEM Auto headlights & rain sensing wipers OEM Bluetooth phone Bluetooth Audio Streaming Reverse Camera OEM Aluminium Package Auto boot close using remote/door button |
#5
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Quote:
I am very likely going to invest in a front pair of struts as apart from this fault the car is excellent. I have had D2’s previously, the best being a 3.7 quattro and although a D4 is an attractive proposition they do not look to me somehow as sleek and poised as their predecessors. I will update the post in the next few weeks, thanks
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Audi A8 2005 D3 3.0 Tdi quattro in Aurora Blue with cream sports seats, DAB Bose sound, 19” five spoke alloys, fingerprint technology and SatNav, wooden sports wheel and gearchange knob |
#6
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Quote:
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Present cars Daily driver: BMW e65 730d Batmobile: 2006 S8, D3, 4E 5.2L V10 BSM with (loud) Miltek SS exhaust, Carbon Fibre trim, Alcantara headlining, soft close and keyless entry. |
#7
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Why not just buy the offending corner?
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Phantom Black 2008 A8 3.0 TDI SE ASB |
#8
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^^This. Unlike normal springs, you can replace just the one corner
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2008 (facelift) S8 with B&O, ACC, glass sunroof, reversing camera, front and rear heated seats, ceramic brakes, homelink, electric side and rear blinds, ski load through, heated fan washer jets, remote boot closing, de-flapped manifold, fridge, umbrella holder |
#9
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If there was anything wrong with the shock I would still be tempted to replace both sides.
That being said the fault has not been diagnosed and I would not be throwing huge amounts of money at the problem replacing parts and hoping that it will cure the it. I don't think you get many issues with struts other than air leaks either bag, o-rings or residual pressure valves all of which could be replaced for a lot less money than whole strut. For all we know it could be lost nut, screw or socket rolling around somewhere making the noise. If it was me I would leave it alone and live with it after verifying that it is not something that affects safety.
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Currently 8less 2011 Q7 S Line 3.0TDI, 2016 Tesla Model S 90D 8 history: 2006 A8 Sport 4.2TDI quattro SOLD, 1997 S8, reached end of life with gearbox failure |
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