Looks like AOS, but engine WOES - 986 Forum - The Community for Porsche Boxster & Cayman Owners

al83s · 08-17-2009, 06:58 PM

Long story short, I got a CEL, drove to Oreilly and pulled codes 1128 and 1130.
Restarted the car - cloud of smoke. Thought it was an AOS, but after a minute of idling - engine started to WOE. I turned it off and towed the car home.
Restarted it w cover off - no woeing at first, just sucking noise and rough idle started to woe after about a minute again.
Oil level is fine, no metal in the oil or on the drain plug. coolant is clean.
Any input is apreciated.

Jake Raby · 08-17-2009, 07:08 PM

remove the oil cap while the engine is running and see if the sucking sound goes away..

sd_boxster · 08-17-2009, 09:58 PM

Maybe it's too late and I'm just not putting it together... WOE?

al83s · 08-17-2009, 10:27 PM

Sorry. English is my second language.
Engine makes noise that sounds similar to wheel bearings going out but more constant. Humming I guess. I will see if I can post a vid tomorrow. No rattling though so I hope its not IMS. Fingers crossed.

Jake Raby · 08-18-2009, 10:10 AM

This may be the IMS bearing!! Is it high or low pitched?

rob76turbo · 08-18-2009, 10:50 AM

I know it could be very dangerous to run an engine with (potentially) the IMS getting ready to fail, but if we could all hear what it sounds like.... it would help us in the event that we are facing the same set of circumstances. Be careful!!!!

al83s · 08-18-2009, 01:09 PM

Taking the oil cap off w engine runing was a PITA, deffinately alot of vaccum there but hissing went away.
Low pitched humming noise was not there today, just a puff of smoke, hissing and ocasional backfiring.
I went ahead and ordered new AOS, Id rather spend 90 bucks before I pull the motor out.
Thanks for the input guys. I will post an update when AOS arrives.
Alex

Jake Raby · 08-18-2009, 01:24 PM

The AOS has two different modes of failure.. Based on the fact that you had vacuum on the oil cap and the hissing went away when the cap was removed, I'd say the AOS has failed in mode #2.

When this happens the engine can be compromised as the extreme crankcase vacuum pulls oil from the oil pick up tube, reducing oil pressure at idle and low speeds..

I just had this happen to me on a test drive a few weeks ago, the event almost cost me my life when the AOS failed and oil vapors lit up behind the car like Haley's Comet...

When the AOS fails with method 2 you need to ensure the front and rear engine seals have not been sucked into their bores by the vacuum too deeply and that the oil fill tube wasn't broken when the vacuum sucked it flat..

Did your oil pressure light illuminate?

sb01box · 08-18-2009, 06:13 PM

When the AOS fails with method 2 you need to ensure the front and rear engine seals have not been sucked into their bores by the vacuum too deeply and that the oil fill tube wasn't broken when the vacuum sucked it flat..

is there a room for improvement here. an anti vacuum value on the main crank case such that the seals does not get sucked in??

BoxsterS21 · 08-18-2009, 08:07 PM

Mine is doing the exact same thing... It does smoke every start up... What do you mean by the two methods of failure?

I have been fighting a non Porsche dealership on this, I am now going to take it to the real guys.

Jake Raby · 08-18-2009, 09:54 PM

AOS MOF#1= Clouds of white smoke, CEL, the engine runs like crap.

AOS MOF#2= No smoke, no CEL. High pitched squeal at idle, collapsed oil fill tube, FMS and RMS pulled into their bores due to high crankcase vacuum, oil pressure indicator may illuminate if oil is at temperature, at idle.

Its all according to what part of the diaphragm fails.... Thats what dictates the symptoms.

and a Dealership may not be the best place to go, some of them have never seen a MOF2 from an AOS and they may tell you that you need a new engine.

I received a perfectly good core this way.. I threw a used AOS on the engine and it still runs today without issues... I bought the engine as a "blown Core" for 300 bucks.

BoxsterS21 · 08-19-2009, 04:51 PM

Mine is doing Failure number one... Thank you sooooo Much! :dance:

944boy · 08-19-2009, 08:55 PM

This post was in good time!! I stopped today at the bank and heard a squealing (motor never makes noise) and when I realized it was my car I popped the oil filler cap and there was a ton of vacuum and the noise went away when removed.

I stopped the car immediately. I will grab a new AOS at the local dealership ($163!!!) but its in stock. I hope I caught it quick enough before damage was done.