I have learned so much from this board.... I have had a 2004 A6 2.7t for 2 months now and fixed a few minor things, but this one I am really worried about. It is my first Audi, so I don't know all of its noises. Any help...since I live 2 hours from Audi dealer.

It makes a loud whine when I start it up from cold. I also hear an escaping air noise with a roar. It sounds like a car that has a muffler problem or something. I have tried to find where its coming from but can't narrow it down...definately coming from engine bay...don't hear it under car. Top of the engine towards the back but closer to the passenger side. After a min or two, the whine stops and the air sound stops, but I can still hear a small rumble, like a hole in the muffler sound. It runs fine and no lights on. I just had the passenger side tensioner seal fixed, (small oil leak). Seems that this started afterward. I am not sure if the engine is supposed to have that deep rumble or not. I know the whine and air escaping noise is new though.
Any advice please help!!!!

 

The whine could be your ex-girlfriend in the trunk. lol. But seriously folks; it could be dry starter bushings, a power steering pump bearing, alternator bearing ready to die, idler pulley, or other stuff. You really need a mechanics stethosope to sort that out. You just put the probe on the suspect part, your ears do the rest, lol. What is the duration and location of the noise?

Sure sounds like a possible exaust leak or a crack in front of the cat. Is it a hissing or a popping, what does it sound like? Can you make a wav. file with your camera?

I am thinking that you have a loose seal flange, and when it is warm, it expands and seals. I would tighten your exhaust pipe connections from the headpipe to behind the cat.

Let us know...

 

Hi,

It only happens when I crank it from a cold start. If its an exhaust leak, what does that entail? It is a whine that is pretty loud, and kind of shifts like louder then softer. While that is going on I hear the sound like air suctioning/blowing, like a compressed air hose. Sounds almost like the suction sound from a vaccuum cleaner hose when you move your hand over it. (sorry im bad with the descriptions). It sounds like its from the back of the engine closer to the passengers side. I hear the roar (air pump) and both sounds stop after a min. or two. BUT... I still hear the sound like a deep rumble like a muffler would sound in the same area but its not loud....so I don't know if that engine is supposed to be like that.

I was wondering if it would have anything to do with the work I had done on the car with the tensioner.

I went and cranked the car a little while ago and no whine or air noise but I did hear the rumble like the muffler sound....of course the car has been driven. I did smell exhaust but not bad, thought it was because I was in the garage (with the door open).
Sorry If I don't make much sense but I really appreciate the advice!!!
The car seems to run good and no lights or problems.

 

If the air pump roars, you have a hose off of the intake or discarge somewhere.

 

Im gonna say its an air pump. Do you have a cel yet?

 

I had a 94 mercedes E420 V8 that had an air pump and it would take a min or 2 to warm up to temp, but it delayed the shifting and the rpms would rev up if i tried to drive it right away without it up to temperature. Is the A6 like that too, cause it seems to be doing that.

No check engine light yet. Engine seems to run good though, no skipping or popping exhaust. After the whine and air suction sound goes away, engine sounds like deep rumble from exhaust but when I get under the car its not as loud. Maybe I am just not used to the way this engine sounds!

Could my indy mechanic have not tightened something when he did the chain tensioner seal? He worked on the passenger back side of the engine and this is where i hear the noises. This engine was running perfectly before and it ran good after I got it back, but started this a few days after.

 

It is possible you have and issue with the secondary air injection system. (I assume this is a Tip tranny because the lucky dudes with 2.7t's with the manual trans do npt have this system.)

Background: The SAI pump, mounted on the top rear of the engine -- just to the left of center, only runs for a short time during a cold start. It pump air through a plastic tube (known to break easily) to two Combi valves mounted on adapters at the rear of each head. The Combi valves are also called Kombi or even EGR valves. These valves are opened when the pump is running to inject clean air into the exhust to help the cats warm up. Failure of this system SHOULD pop a code for low flow. (or something like that) It may need to be bad for a few start/stop cycles before you get a CEL.

Now for your problem: I suspect a broken or disconnected plastic hose to the kombi valve. (The escaping air noise with a roar -- exhaust back feeding through the kombi.) Your injection pump may be starting to go bad. (The whine)

 

I too have the same problem, mechanic changed the pass side gasket and now I have the exhaust leak noise... checked the kombi valve connection and feels OK don't know what to do ... change valve or hose ?

 

if it sounds like this its your secondary air pump.

Audi secondary air injection pump - YouTube

if you have this sound then it means the pump is on its last leg. my pump just died after a year of making this sound. so you have time no worries. pump is 400 on ecs tuning and almost 1000 at the dealer.

 

If you only hear the noise only on cold start-up and have no CEL...I would say that its perfectly normal and sounds like the air pump is doing what it was designd to do. You should remember that most cars have smog pumps/air pumps that are driven off of the engine drive belt. Most Audi's, BMW'S and Mercedes have electric air pumps that are noisy for the first couple of minutes after cold start-up and aside from the whining noises you will also hear a noise similar to an exhaust leak. If you don't have any CEL, I wouldn't worry about it.