LADO

terrible thing has happened to me yesterday, my car is 04 c4s tip, at 6000 rpm suddenly engine started knocking and sound was like lots of metal things are smashing to each other (not very loud). at t the very same moment i looked in to the mirror and saw the cloud of white smoke, there was a lot of smoke. as soon as i saw it i shut off the engine and stopped the car. from starting the strange noise and shutting the engine off was just 1 or max 2 seconds. what do you think if it was an IMS failure is it possible that damage is not huge because it continued just 1 second? or was that something different? perhaps if it was an AOS failure could it make a knocking sound?? car is towed to the porsche center, but they are too busy these days and mechanic will check it after 3-4 days, i will not sleep these 4 days... so what is your ideas? at the moment all i know that engine oil is crystal clear and normal level (but on dipstick, how is on filter i don't know) coolant is in normal level and there is no oil inside. engine oil cap is clear. there are no oil leaks under the car at all. i 'm not able to find out any more details at the moment.. any ideas??

808Bill

Make sure the shop does not try to start it or they'll cause more damage (they don't care) and it will cost you!
Was it a knocking or screeching noise, like a belt slipping or bearing grinding? If you where close to the car there are some things to look for but it sounds like you just have to wait.
How many miles on the car?

LADO

everything happened so quickly that i don't remember exactly sound, as i remember sound was more like bearing grinding and knocking, but wasn't loud it was quite and not aggressive sound
car has 100K miles, and i dont know if IMS was changed or now, i was about to change it

808Bill

AOS is going to be my first guess, but make sure the shop does not start it! I just went through this a couple of weeks ago and thought the worst as the sound was horrific.

LADO

thank you for your advice, i will make sure that thay dont start it. hope you are wright and it's AOS. was that AOS in your case?? is it a costly repair if it;s an AOS?

808Bill

Yes but if you already planned on doing it all together it won't be that bad. See my "Blown Motor" thread Not Blown.
https://rennlist.com/forums/996-foru...ht=Blown+Motor

Imo000

The noises you've described is not the AOS. Sounds like your engine Fubared itself as the rotating assembly came apart at 6K rpms.
Even if you really did shut it off after only 2 seconds, that's 200 revolutions at 6K rpms ( (6000/60)x 2=200 ). A lot happens in 200 revolutions.

808Bill

I was trying to save the poor guy a few days of agony!

Astro

My water pump went out last year and sounded like this, but there was coolant leaking after I pulled over and shut it down

808Bill

Any update?

NuttyProfessor

First of all, sorry OP that you're experiencing this failure so soon into ownership. Seems like there have been more and more failure threads these days surrounding the 996 C4S. IMHO, the sounds and other symptoms leads me to believe the outcome is not going to be good. Once they drop the oil sump plate, you'll get the prognosis. I would speculate, based on the sounds, that you've broken a timing chain. Let's hope the engine can be saved regardless.

I hope for the best given the circumstances.

TomR9964S

I also have a 04 C4S tip and had the AOS go out. Big cloud of white smoke but I don't remember any noise. Hopefully, you just heard your heart go into overdrive thinking the engine is gone. Thankfully, the guys on here calmed me and it was just the AOS. I'll try to attach the invoice from my indy. I had some other stuff done, but when they dropped the engine some of those 14 year old hoses were brittle and broke.

LADO

thank you for your support

Very strange situation, but i'm very very happy

As i said before Mechanics had no time for my car for 4 days, this 4 days were very difficult for me, because i was afraid that it was IMS,... after 4 days of waiting finally came that moment when they started to take it apart. at first they tried to start it, but as i was told here not to start it i asked them to rotate it by the hand at first and it rotated, that was first good sign. after that i gave them permission to try starting it, and it started like nothing happened, for the first few seconds white smoke came out from the exhaust and then is cleared... so nothing was wrong with car, i was in shock, it was very very happy moment but obviously AOS is not working properly and i am changing it.
also please advice what else should i change to prevent an engine damage, apart from IMS.

also i just can not understand what was that terrible noise from engine if nothing happened?

808Bill

That's fantastic news. The AOS failure can make a horrific noise.

I am very concerned that your mechanics first instinct was to try and start it. This tells me to look for someone else that has more experience cause they could have cost you a bunch of money ruining your motor!

DBJoe996

When the AOS gives up a lot of engine oil, or coolant, or both gets dumped into the intake. When that is sucked into the combustion chambers, it is noncompressible and is sounds like someone dumped marbles in your engine. You may have dodged a bullet because the engine didn't hydro-lock. Hopefully it is just the AOS.