AOS breather line replacement
 

I managed to crack the lower breather line coming off my Air/Oil separater in my 2003 986s. (the plastic accordion style hose that comes off the lower port on the right side of the AOS when standing at the back of the car looking towards the front). I did a homemade glue+tape job on the hose but I don't think it's a good permanant fix.

I actually cracked the upper plastic hose last year but that one was easy to replace. Anyone know the technical name for the hose coming off the bottom right port and where the other end of it goes? I tried looking on pelicanparts and in my bentley manual but I can't find any info. Looking in the engine bay is making me wonder if this is a "drop the engine" professional kind of repair job..

Any help is greatly appreciated

For a 2003, the part number is 996.107.147.58.

Porsche calls that part a "crankcase breather hose".

Also, did you crack the actual hose or just the flexible circular connector on the end?

If that's what you cracked, you can replace just the end by swapping it from the end of a new part.

Regards, Maurice.

Amazing, thanks for the quick response. I can't thank you enough for taking the time to respond.

Wonder if I can manage to snake the old hose out and new hose in by taking out the throttle body or if I should just bite the bullet and have a dealer do it. I hate the idea of having to pay a ridiculous price for a (in theory) simple hose replacement.

Thanks again for your help

Sain0rs:

Before you go biting that bullett, why not inspect how much access you have if you just remove the two rubber intake distributors. That only involves unscrewing eight thin, large diameter screw clamps, two small vacuum connections and the throttle body.

Great opportunity to clean out the throttle body as well.

I recently did that with my friend Boxtaboy and it was very straightforward.

I'm not positive, but I'm reasonably sure that to be able to disconnect that end of the crankcase breather hose, you will also have to remove the driver's side intake manifold, but not the passenger's side one.

Here is a photo of that area after removing the two intake distributors and the throttle body:

http://i53.tinypic.com/a9qwit.jpg

The red arrow points to what I think is the crankcase breather hose in question. The yellow arrow points to the right rear corner of the oil cooler, for reference.

If you take a look at the parts diagram you can see the shape of that hose and the connection at the far end:

http://i55.tinypic.com/13yovf7.jpg

Regards, Maurice.

Great idea, just ordered the new hose so we'll see how it goes after it arrives.

Can't hurt to try first before taking it to someone else.

Thanks for the pics, I've been looking around at pedro's garage etc for reference pictures as well.

I recently broke this same breather hose and I'm about to tackle this same job. Anyone out there have photos, links, and/or insight they can share? If not, I will take pictures and jot down notes. Will post what I learn as I go through this job as I haven't been able to find much info on this task.

I recently did his with an engine on a stand in a well lit comfortable garage with all the tools and equipment. Awful !
1. the old hoses are very hard+brittle. This makes moving them into alignment very difficult.The consequences of a small crack/leak will drive you nuts with faults and problems
2.The old AOS connection used an "0" ring. This O ring swells slightly with oil+heat. When you try to refit ,the clip will not quite snap closed. Do not try force it ! Remove the old O ring an replace it with a new one Works just fine then!
3.The seal on the newer AOS is different. That may be easier ? The new seal looks like a sleeve on the AOS ,not an O ring in the hose. So figure out what you have first?There are some useful Youtubes on this.
4.Scrupulous cleanliness and a little Vaseline seem to help.
5.Be careful and patient because removing old cracked hoses and threading through new ones in such cramped conditions is difficult for a noob. I have no idea how anyone with large hands could do this.
6.Be ultra cautious about damaging other vacuum or electrical connections. There are many obscured ones buried underneath the inlet manifolds.
7. Ask for a referral to an Indie in your area?
8. Allow lots of time if you diy and have a backup plan in case any of the above happens
Good luck !Forewarned is forearmed

I am having my AOS and both lines (Top and Bottom) replaced by my Ind Porsche repair shop on Monday 12 Sep 16. Could do it myself but having it done professionally is a piece of mind for me.

p.s. $500 to get done and I bought all the parts myself.

Thank you both for your responses! SteelStroke, thank you for sharing your quote. I will use it to earn points with my wife when I tell her I saved us approximately $500 in trying to fix this myself. I hear ya on the piece of mind. Hopefully, I don't screw anything else up in the process...

I'm half way through this job or at least I have the old hose out. Gelbster, I can attest to how brittle those hoses are. That, in fact, is why I find myself where I am today; I originally broke the old (lower) breather line while recently replacing my AOS. Then, while removing the hose out from the engine, I broke it two additional times. To get the old hose and the "connection piece" (part #6 in the previously posted parts diagram) out, I've had to remove the throttle body, and the two intake distributors and their boots (4). The new hose is much more pliable than the old one and so I'm hopeful I'll be able to thread it in without having to take anything else apart. Fingers are crossed! To clarify for anyone reading this, I have a 2003 986 with a 2.7L and Tiptronic Trans.

Rooster,
I replaced mine a few months ago without removing the large intake hoses but I did remove the engine access behind the seats because it wanted to ensure that the hose will be properly connected to the breather valve on the crankcase.

Also as Gelbster mentioned, be careful with the small vacuum hoses and the electric connector (fuel breather valve?) that it is on the way of the AOS hose, just take your time and ensure with a mirror that the o-ring at both ends of the hose sits inside the connector all the way around.

Good luck!

Gilles, thank you for the good luck. Yes, I also pulled the front engine access panel. I did it so I could disconnect the hose and replace that breather valve/hose connector piece (996.107.047.00) that bolts to the engine next to the air conditioning compressor.

I've taken a lot of pictures to help me for when I go to reconnect all the vacuum lines and electrical connections so hopefully it all goes smoothly.

In regards to the o-rings you and Gelbster mentioned: neither my AOS (996.107.026.01) nor my breather hose (996.107.147.58) had an o-ring for the connection between these two parts. A new design? Not sure but my parts catalog shows 4 versions of this hose and 8 versions of the AOS with my part numbers being the "newest" for both parts. I'll look at the lower breather hose nipple on the AOS again to make sure but I didn't see an o-ring.

Anyway, the hose has been completely threaded across the engine to each connection area. Now, I have to install the breather valve hose connector piece (996.107.047.00). Not looking forward to that. The bolt on the forward side of the engine was a breeze but the aft facing bolt - I'll be doing it blind and if I drop it, it will be a nightmare retrieving it. Anyone know the torque specs for these two bolts? My guess would be something in the neighborhood of 10lbs?

Rooster,
Each end of the new hose should have an o-ring inside, where it mates with the AOS at one end and with the valve at also the breather end, and if I remember correctly mine where blue in color, you should lube these o-rings so they go in smoothly :rolleyes:

I stand corrected. There were black o-rings on both ends of the breather hose. The hose is installed. Now all I have left is to clean the throttle body & intake parts and reassemble!

I Congratulations!
Now you can tell your wife that you saved $500 towards that nice exhaust you always wanted..:)

I have an 02 Boxster S tiptronic. I cracked the lower AOS breather hose as well when installing new AOS. . It was brittle from heat and age. How did you get the new lower hose on? I have a new one but can’t even snake it in on the drivers side. Once one side is in how would you get in the other? Did you remove everything on top including the plenum? I’ve removed both cross tubes but still can’t get it in. Has anyone replaced this breather line with something more flexible like heat shielded rubber or silicone hose?

Hola Jose,

If you remove the engine access cover behind the seats you will have more room (and you will be able to see what are you doing..), that way you don't have to remove the intake plenum.

Good luck!

I removed the access panel behind the seats. Unfortunately, it’s blocked by pulleys and the view is terrible. I can’t really see. Has anyone done a write up, or can they tell me how they did it. I am stuck. I don’t really want to remove the intake manifolds.

I plead ignorance.
 

Is there not a workaround? Maybe employ the connecting ends of the tube with a flexible silicone hose or something along those lines? It's an obvious question for which I don't have the answer.

Actually, aren't there a variety of hoses and lines that could be replaced with less challenging alternatives?

I look at that hose and, not yet having seen the actual one in my bay, wonder why you couldn't cut off the ends and secure a flexible hose. It seems so simple, so I'm sure someone will tell me why you can't.

Thank you.

:confused:

In the absence of a why it can't be done, I'll assume it can. Gravy.

Perhaps it can be done that way, but all that fuss is completely unnecessary as the factory hose can be installed, albeit with a bit of effort, but without any cutting or folderol.....

Yeah... I've been reading about that effort, and it sounds like a real pain in the ass.

"Effort" sounds like an understatement, from what I've been reading.

Thank you for your response. With all due respect, "perhaps" doesn't answer my question.

Can someone tell me why you can't cut off the connecting ends... affix a silicone or rubber hose... then snake it to the fitting opposite the AOS? Is there a way to effect the replacement of the AOS absent the hard line that is a fuss to install?

Thank you.

I have the new hose sitting on my workbench ready to be installed. I took a look at where the hose terminates under the left (drivers' side) manifold and it doesn't look like an easy job. If you pull off the engine cover/firewall from the passenger compartment you can see (barely) the connection at the end of the hose. How to reach that without manifold removal is not real obvious.
I would be interested to hear how others have replaced that hose with or without manifold removal.

i'd love to get rid of that hose. impossible to get at, gets brittle, and is in the way of a lot of tasks on the engine - pretty much anything that requires moving the intake. and, with my ac, sai, and ps off the engine, it is the last piece of clutter. i've often thought of fabricating a replacement. doing as start says must be possible, as it is often done with with the shorter aos hose to the intake.

You know... specifically I was going to quiz you on my inquiry... but somehow I knew you'd chime in. I'm glad you did.

Since you've had the intake, sai and ps out... did never you say to yourself "I'm going to employ silicone/rubber."? Do you believe that it could be done with silicone/rubber tube/hose? isn't there an alternative to the hard line? Would it be terribly difficult to affix the new silicone/rubber to the connecting ends (once they've been sawed off the hard tube)?

Thank you.

Outstanding! Thank you.

That's the top hose. Do you believe the lower hose would be amenable to the same procedure... cutting the connecting ends... snaking the flex/sil/rub hos from the AOS to the final destination?

I'm just looking for finality. Don't want to beat this subject to complete death.

Thank you, RK.

i presume they are very similar - diameter, end connectors, so see no reason why not.

Is there a lot of vacuum in that line that could cause a softer hose to compress, thereby causing problems?

don't think much of an issue - all kinds of aftermarket aos systems for flat four subuarus on the market - use whatever hose they do.

The collapse under full vacuum issue is a wise question. In general the larger the diameter for a given wall thickness and compound, the more likely it is to collapse. So suggest you avoid cheapo hose , try thick wall or reinforced wall. The problem is that may be too stiff ??
If someone ever finds the 'sweet spot' for the spec of the required silicone hose, it would be very useful for some Forum members.
For the picky, it may not be Smog-legal but at least it would never fail again ?

Well, mine was totally brittle and cracked the corrugated part right off.

Has anyone come up with a replacement for this yet?

Thanks.

The best replacement is the factory one. Can't really come up with something different due to the way the lines connect at each end, but that doesn't mean you can't come up with a solution.

True dat, as the kids say.

Ok, I'll bite....anyone have a solution for one of these hoses where the end that connects to the AOS has broken off? I can feel there is an inch or more of corrugation left before it appears to move to smooth rubber.

This is an older parts car that I am working on, but it is in the way of construction that will be happening soon, and I'd like to be able to drive it away, so second thought is will it actually drive with this breather hose disconnected? For about the distance of 1/2 a city block?

if the car starts and engine runs, then drive it. will not run well and expect you would spray oil, not have any vacuum but if you could move the car. If you dont want to replace it with a factory one then make one from the hose you have that's broken, pictures are right above.

That would work. I just don't want to damage the car by not having it connected....could be possible to block it off before moving it I guess in the short term.
Not necessarily planning to NOT replace it with stock, just under a time limit here.

dont block anything. just start it, move it to where it needs to go and then park it.

Sounds good. Hopefully she starts after sitting for the winter.

Where are you located?

Central Alberta, Canada. Not on here much, but I will edit my profile.

The best upgrade for the AOS hose should be a material unaffected by oil,heat and vacuum. The 2 obvious candidates are reinforced silicone(see #21 above) or corrugated (yellow) natural gas line(Home Depot). You'd have to adapt some fittings and paint it matte black to look stock for Smog.