AOS is bypassed

[mjdown2971]

Recently purchased a 98 boxster. Some oil leaks led me here. I've changed the plugs and tubes, and replaced some missing bolts in the coil packs. Still ended up with leaks that pointed to the AOS. I open her up and the AOS isn't there, it's capped off at all hose points! Has anybody else ran into this? What are the dangers of doing this?

[JFP in PA]

Welcome to RennTech

The reason you are getting oil leaks is the missing AOS.  You could literally blown out every seal in the engine running it this way.  Bad idea.

 

Why wasn't this caught during the pre purchase inspection?

[mjdown2971]

This is my first Porsche, I didn't even notice anything missing and the car ran great except for a few drips that I thought was from the tubes. Wasn't familiar with aos until researching.

There are 4 connection points for the aos right? The intake, the block, the crank, where does the back smaller in diameter lower hose go to? Oh and all the hoses are missing too.

[JFP in PA]

6 minutes ago, mjdown2971 said:

This is my first Porsche, I didn't even notice anything missing and the car ran great except for a few drips that I thought was from the tubes. Wasn't familiar with aos until researching.

There are 4 connection points for the aos right? The intake, the block, the crank, where does the back smaller in diameter lower hose go to? Oh and all the hoses are missing too.

 

On your vehicle, there are two hoses on the AOS, one running to the PCV valve on the engine, the other back into the engine case, plus the arm that allows the oil to drain back into the engine, plus a third vacuum line:

 

[mjdown2971]

Yeah I'm pretty sure I'm going to have to replace all the lines along with a new aos. I'll have to get in and see if there's anything left of the old lines when I get home, but they appear to be removed.

Hopefully no major damage has been done, I've only put about 100 miles on it since owning it, not sure how long this hack has been in place.

[JFP in PA]

2 minutes ago, mjdown2971 said:

Yeah I'm pretty sure I'm going to have to replace all the lines along with a new aos. I'll have to get in and see if there's anything left of the old lines when I get home, but they appear to be removed.

Hopefully no major damage has been done, I've only put about 100 miles on it since owning it, not sure how long this hack has been in place.

 

Some simple rules on the AOS: Only use factory parts; the aftermarket units are terrible, often failing right out of the box.  The AOS is a consumable, it needs to be monitored and replaced when necessary.  Porsche shops typically use a digital manometer (around $40 online) connected to an old oil fill cap to test the AOS; when the vacuum on a fully warmed up engine exceeds 5 inches of vacuum, it is time to replace it.

[JFP in PA]

[mjdown2971]

Thanks for the help Jeff, I'll let you know how it all pans out once I get everything back in. 

[mjdown2971]

Any tips to where to get the best price online for the parts? Is that ecs tuning reasonable?

[JFP in PA]

ECS tuning is one of the last places to go; board sponsor Sunset Porsche has the best online prices for factory parts.

[DBJoe996]

Good technical article on 986 Boxster AOS replacement - https://www.pelicanparts.com/techarticles/Boxster_Tech/09-ENGINE-Air_Oil_Separator/09-ENGINE-Air_Oil_Separator.htm

[JFP in PA]

His problem is probably worse; he needs to replace more than just the AOS, he probably needs new hoses as well, including the dreaded one that runs over the top of the engine beneath the intake manifold, always a treat to replace

[kbrandsma]

Yes tough work putting that all back together.

Edited August 4, 2018 by kbrandsma