Hissing near rear passenger wheel

[AudiDWK]

Hey everyone, just wondering if you might know what this is:

After go out for a drive and I put my car in park, I can hear a distinct hissing noise coming from under the body, near the rear passenger area. It's an intermittent hiss (hiss-hiss-hiss-hiss-his-hsisi-hshis-hiss-hiss instead of hissssssssssssssssssssssssssssssss!). I can only really hear if I step out of the car, and the noise stops when I turn the car off.

I'm not sure, but maybe it's a problem with the fuel filter??? -noob speculation.

[A4DJ]

I noticed this on my buddies A4 the other day when he popped his hood. His "hiss" was up near the cabin filter area and was present for about 30 seconds after he turned his car off, then it stopped. I would also like to know what this is to help him out.

[TCHUN003]

how many miles do you have on the car?

[AudiDWK]

how many miles do you have on the car?

I have around 38k miles

[phantom b6]

I have noticed the exact same thing! 49k miles

[AudiDWK]

I have noticed the exact same thing! 49k miles

So what do think? Fuel filter? I'm going to see the dealer today- I'll let you know if i find out anything

[has6]

Leaky prop shaft gasket?

[My OOOO My]

It is the fuel filter.

That symptom has been covered here on AZ many many times.

Since you have an '05, check with dealer if you are covered under warranty.

[Mikef5000]

I noticed this on my buddies A4 the other day when he popped his hood. His "hiss" was up near the cabin filter area and was present for about 30 seconds after he turned his car off, then it stopped. I would also like to know what this is to help him out.

AC system equalizing. All is good.

[A4DJ]

AC system equalizing. All is good.

I will be sure to let him know.. thanks he'll be happy.

[phantom b6]

I'm pretty sure it's my AC as well.... The fuel filter noise appears to be a humming or whining.. mine is just a hissing and I haven't heard the noise in the past few days since it's been cool and I haven't used the AC

[AudiDWK]

Hello - just got back from a drive - no A/C - came home, and the hissing is still there. If it is a normal function, I'm not sure it is a very nice design, because the noise can be annoying, and it's fairly obvious. I'm just not sure if Audi would intentionally make it that way, but we'll see.

Thanks for all your input guys. In summation, one person says: definitely fuel filter; another says: definitely A/C - basically, inconclusive =). But I'm going to the McKenna dealer in Norwalk tomorrow morning - I'll report back with whatever they tell me.

[EUROaleksey]

I also got a hissing noise when I replaced my fuel filter... passenger rear side... but it isnt high pitch hissing... it sounds like woosh... VERY quietly as if ur neighbour left water running and u can hear it through the wall...

is it bad for the car? should I have it checked out? I'm at 131,000 miles and no leaks no rust and gas milage is better than ever (if that's a factor)... can someone tell me? should I leave it? I drove like this for 10-15K and havent had an issue..

thanks :)

[Brian66D]

i have a similar sound coming from the rear underneath.

mine sounds more like a rubbing sound, and you can hear it inside the cabin too...it stops immediately as soon as the key is turned off

mine is a 5MT. and its been doing it for at least 20k miles, its just driving me crazy

[AudiDWK]

The verdict is in

I just came back from the dealer - they switched out the Fuel pump and Fuel filter. The mechanic told me it was pretty dirty (I have 38,000 miles).

I drove home, which was about 10 miles away, with the A/C on - parked in my garage, and lo and behold! Not even a peep - no more hissing. All I can hear from the rear now is the engine up front - it's like night and day. In my case, swapping out the pump and filter did the trick (Unfortunately, I'm not exactly sure which component actually remedied the hissing - but it was certainly one of the two). I knew that it couldn't be normal.

I hope this helps out for those who are experiencing hissing as well. If you've got an existing warranty go for it - it was covered! But warning: have someone come with you in a separate car so you have a ride back home, the wait will be several hours (unless they'll be gracious enough to offer a rental or loaner - probably not though).

['97 slvr bullet]

I have a '97 a4 body. for the drivetrain i have the 01 s4. Just the other day weather was nice outside. took it out for a afternoon drive, in the evening time is when i heard the hissing sound coming from the rear passenger side of the car where the fuel door is... also at the same time I am losing major power loss no turbo power under WOT at that point I thought that I had a boost leak. So when I parked my car looked under the hood checked for cracks in any of the hoses and couplings, no cracks were found. Jacked my car up looked under the car, all the couplings are fine under the hood. Car runs fine at idle, stepping on the gas pedal, i let it rev up to 6k rpm no hesitation, but when I take it around the corner in first gear it will go at half throttle, but when I try to go WOT it hesitates big time, turbo gauge looks likes it malfunctioning, but turbo gauge works fine. So I am thinking that I have a bad fuel pump and fuel filter.

Another thing that happen to me yesterday, while driving to meet up with a friend, I had no power at all, couldn't even make it up hills on the highway, only if I was doing like 60-70 mph. Then at one point I have to drive on the shoulder to get out of the way of traffic, when going up the hill on the shoulder no power car was still running, gas pedal to the floor, rpms not moving had to come to a complete stop, then try again in 1st gear. So now I am assuming that I have the fuel pump and fuel filter that needs to be changed.

Oh by the way when idling I have the usual clear white smoke coming from the exhaust, so I don't have any turbo problems, if I did I will have black smoke coming from the exhaust.

Any comments would be greatly appreciated.. Thanks