I have a 2000 A4 Quattro and there is this weird sound coming from the engine. im not exactly sure from where but it sound like every 10 to 20 seconds. it almost sounds like if something is releasing air. this even sounds when the car is off and when the car is on and running it dims my lights. this morning my batery was dead. what can this be? please help? i really need my car running! any feedback will be apprecitated. Thanks a lot!

 

a/c compressor? maybe the lines got crushed or punctured and it keeps cycling. that wouldnt be when the car is off though. possibly an electric fan or something else thats pulling a lot of power?

you really need to get in there and figure out where its coming from. that description is very vague.

 

Whoa.. wierd. You have air suspension or something?

 

If you have the means, and audio/video clip or a picture of where you think the noise is coming from would help us help you

 

Is it an air sound or are you sure its not a short making that sound? A video clip would definatly help you get more feedback

 

how about your air lock pump

 

I actually know the exact sound you're describing, or at least I think I do. One of my 1.8T's did this once and I'm trying to remember why, I have the noise stuck in my head but I'm starting to think it may have been on my E46 BMW when the cooling system was screwed up, all these cars I've owned are blending together in my head. Either way is it like a loud air-like click and then you're RMP's drop a little and lights dim, then it goes away for 20 seconds and comes back? Did this start after your battery was dead or before, It could just be your alternator and fan straining the engine while its idling and trying to recharge the battery.

 

Its not very loud. you have to really listen to it or has to be super quiet for you to hear it. this happened before my battery died. thats the reason it died because the noise keep sounding even when the car was off so it drained my battery i think. i seriously dont know whats wrong and i cant afford a mechanic right now.