Jump to content

The RennTech.org community is Member supported!  Please consider an ANNUAL donation to help keep this site operating.
Click here to Donate

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)

Recommended Posts

My 2004 Carrera coupe has developed a leak.  It started after I flushed my cooling system.  Rather sure it is around the AOS/associated lines.  I've read various opinions about the difficulty of removing the AOS.  But what I am interested in doing is just replacing those lines.  Any experience or opinions on doing this?  Specifically, is it even possible?  Especially if this can be done without removing the intake manifold?


Also I am only finding the upper oil separator coolant hose.  What about the second one?

Link to comment
Share on other sites

  • 1 month later...

Having done an AOS replacement on my car, you cannot access the AOS coolant lines without removing the Bank 1 intake.  No way to get to those hoses and clamps, even with the motor dropped down to the lowest point.  You might as well just replace the AOS while you're at it.

The coolant lines #12 and #13 - #12 comes from the water pump and #13 crosses over and goes down underneath the engine.

See diagram here http://www.autoatlanta.com/porsche-parts/hardparts.php?dir=996-99-05&section=104-10

For a temporary fix, or total bypass of the coolant to the AOS, one just needs to plug the two hoses or find a way to connect them together.

Edited by DBJoe996
Link to comment
Share on other sites

  • 1 year later...



I just removed my AOS (detailed removal write up to follow later) and noticed that the 2 coolant lines located on the sunflower face area of the AOS have no hoses attached to them!  Obviously the AOS was previously replaced but the original hoses were never connected.  And these 2 nipples were not blocked off/bypassed or connected together as mentioned above. 


So my question is where do these 2 AOS coolant hoses go/connect to? 


When I was pulling the car apart, the thin coolant hose that goes from the engine block cap (right below the alternator and connected to the joining socket part Number 99610622652) was connected directly to the 3 way splitter hose (which connects to the water pump and the expansion tank).  I'm thinking this is hose 13?


I'm thinking this coolant hose should originally be going to the AOS (right side nipple of the face) and then the left side nipple of the AOS coolant hose (hose 12?) should be going to the connection on the 3 way splitter hose?   I'm really confused now.


Car is a 1999 manual cab C4.

Edited by rhkwon
Link to comment
Share on other sites

That doesn't make much sense.  The coolant lines going to the AOS are under constant pressure from the coolant system from the connection on the water pump, so they have to either be internally blocked or connected together to make a loop bypass.  The coolant lines to the AOS help heat up the AOS during low temp running/first start up to assist with air/oil separation.

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.

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.