Jump to content

Server Lease Renewal/Software Licenses

Our yearly server lease, software licenses, as well as hardware operating costs, ARE due Dec 6th, 2021. Our current donations have fallen far short of the funds we need to renew. Please remember the RennTech.org community is Member supported so please consider a donation to help...  THANK YOU!

Welcome to RennTech.org Community, Guest

There are many great features available to you once you register at RennTech.org
You are free to view posts here, but you must log in to reply to existing posts, or to start your own new topic. Like most online communities, there are costs involved to maintain a site like this - so we encourage our members to donate. All donations go to the costs operating and maintaining this site. We prefer that guests take part in our community and we offer a lot in return to those willing to join our corner of the Porsche world. This site is 99 percent member supported (less than 1 percent comes from advertising) - so please consider an annual donation to keep this site running.

Here are some of the features available - once you register at RennTech.org

  • View Classified Ads
  • DIY Tutorials
  • Porsche TSB Listings (limited)
  • VIN Decoder
  • Special Offers
  • OBD II P-Codes
  • Paint Codes
  • Registry
  • Videos System
  • View Reviews
  • and get rid of this welcome message

It takes just a few minutes to register, and it's FREE

Contributing Members also get these additional benefits:
(you become a Contributing Member by donating money to the operation of this site)

  • No ads - advertisements are removed
  • Access the Contributors Only Forum
  • Contributing Members Only Downloads
  • Send attachments with PMs
  • All image/file storage limits are substantially increased for all Contributing Members
  • Option Codes Lookup
  • VIN Option Lookups (limited)

Rear hissing "shhhh" noise at rear - ideas?


Recommended Posts

Hi 996 friends,

 

I have a '99 Cabrio with 79K miles.  4 yrs now.

 

Just recently, I noticed at idle, or at any relative throttle, there is now a rear hissing constant "shhhhhh" noise that I can hear above the normal engine rumble when I'm inside the car.  It sounds like it's coming right from the other side of the rear bulkhead.  The noise gets progressively louder as the throttle increases.  When car shuts off, noise is gone too. 

 

The car's performance is unchanged, it is fully responsive in the full throttle range and at idle as it should.  The only difference is this new noise that has the same characteristic of like air constantly leaking.  The noise is constant and steady, no interrupted lulls or breaks.

 

When I try to hear the sound with the bonnet open and engine running, I can't really pinpoint where it's coming from.  I want to say from the middle to right side of the engine.  The engine noise from the outside clouds the "shhhh" , so it is most noticeable from the interior of the car with windows rolled up.

 

Also to note, there are no fluid leaks on the car or any other signs that could indicate a problem.  The only thing I did this weekend was have the convertible top changed, and when I drove it home from that it was fine.  Then on my next trip, I started to notice it.  Perhaps coincidence.

 

Anyways, thanks a bunch for any insight as to what the cause of this may be.  It surly has me scratching my head!!

--Randy

 

Link to comment
Share on other sites

So I believe I know what the problem is.

 

I'm getting random idle fluctuations at stops,  constant hissing sound from rear bulkhead,  oil cap with car on has a rather strong vacuum when I try to remove it,  and there is some light white smoke coming out of exhaust when I start car for 5 to 10 mins.  I think the AOS is the culprit.  No CEL.  Thoughts? 

 

Thanks.

Link to comment
Share on other sites

Thanks JFP for your insight.  Yeah, it took me a little while to understand it.  I guess I totally had forgotten about the AOS.  Although I'm a DIY fanatic, I called my indie mechanic to get an estimate on what the total damage is going to be.  This job may be a little more than I want to handle, especially since I want a warranty on this in case for some reason this goes wrong the first time.  . All the symptoms are making perfect sense to pointing tot he AOS.

 

-Randy

 

 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.