2001 A6 4.2, 105k miles. Well, I'm almost through the springtime from Heck. I had to replace my front outboard CV boots (ruptured within a week of each other, so I replaced the whole joint). Also my right front wheel bearing, my left front O2 sensor, and my air mass sensor. Also my front rotors and pads.....

That was failed stuff. And the car ran like new, maybe better, when I was done. So then I tackled what I had intended to do this spring in the first place- timing belt. I bought the kit from Blauparts.com, and went at it. A few stumbling blocks, but anyway it's all buttoned up again now. Started instantly. But there's a hum that I suspect is the timing belt.

I'm prettysure it's not too tight. I set the eccentric roller with the 5mm gap at the tensioner, and when I released the tensioner, it measured at 6mm- the high end of acceptable, which is the low end of acceptable tension.

Every idler and tensioner was replaced with new, as was the water pump. (Thermostat too, but I doubt that's what's whining.)

I've read that timing belts may whine when new, but settle out after a few weeks of driving. Well, that'd be great news. I have only about a half mile on this so far.

It could also be the new serpentine belt, I guess. I put a new tensioner in for that as well, but obviously the A/C, alternator, and power steering pump are original. Mileage is 105k.

Any suggestions??? I'm going away for a week, so it'll sit for now. Front bumper isn't back on yet anyway- I'll wrap that up when I get back.... Thanks for any insights, Jim

 

Make sure the timing belt cover is not hitting the belt. There is a smalltab on the cover that suppose to stick out on the outside. Common noise problem afterthe timing belt service. Almost thought about towing mine back to the mechanic but figured it out

 

My advise to you would be to call blauparts and consult. I installed a blauparts TB. kit myself and when I had quesions they were VERY helpful, although it was difficult to get thru the telephone maze. BENG

 

Update- turns out, JLaws was right. the front left (driver's side) cam sprocket cover must've been touching the belt. I took it off to observe, started the engine, and the humming was gone.

Also, beng is right as well. Blauparts are great about giving technical advice. Keith checked with their mechanics and called me back within an hour. Sometimes there is a hum with a new belt, due to the precise fit of the trapazoidal teeth into the sprockets. May take a short while for them to wear-in, but like I said, turns out that wasn't my hum.

The kit approach was great. I'll post some tips and observations I made whilst doing the job shortly.

Jim