KeithManton

I have a 2003 A6 4.2 V8. Had an engine service by German Auto specialists in Marietta GA at around 135,000 when they said timing belt, serpentine belt and tensioners etc were fine. Not known if ever changed as it had 102,000 miles when I bought it.
Now at 178,000 the last few months have had a mechanical rattle when starting, lasts only 2 seconds and then smooth and quiet, pulls like crazy and no performance issues at all.
Oil is full synthetic and changed every 7,000 miles, uses about a quart in between services. Driven hardish, but not too hard.
Any thoughts on what may cause the rattle?

Prospeeder

Well if the timing belt was done its getting about due again. So plan on doing that soon. So the rattle is probably just one or both of the chain tensioners making abit of noise on startup. Rather common and considered normal. If the noise clatters on for 10+ seconds or never stops thats when the chain tensioners should be replaced before total failure. Does it sound like internal noise to you? Remember, The timing belt drives one set of cams, that each have a chain and tensioner inside the engine to drive the other set of cams. Thats probably what your hearing. Open the hood and listen while somebody starts it to see if you can distinguish if its side specific noise.

KeithManton

Thanks, I plan to take it to my local Audi specialist to see about getting this done but am looking at buying a 2007 V8 off e bay with 84,000 miles.
However, I would not try to sell this one unless I had it fixed.

Just Me

hydraulic lifter? As for the timing belt - you cannot check the belt, because its rarely the belt that fails - its a water pump, idler, or tension er that begins to wobble or seize, adn then takes the belt ( and your motor with it) out.

But your noise sounds like lifters. Mostly harmless. Could also be chain tensioners sticking.

Grant

KeithManton

Stop press, just after I posted the car overheated stuck in traffic in 100 f weather. My shop found water pump and tranny fan needed replacement and while it was all open they did a full timing belt service. The rattle is still there on occasion but not as bad or as frequent. They too, think it is a tensioner sticking and have put an oil additive in to free it. I am taking it back to have it drained and refilled....$2,100 for the lot which I was quoted more than that just for the belt service before, so a good deal me thinks