Porsche 997S-2005: Screeching noise from Engine
06-22-2017, 09:33 AM
#1
5th Gear
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Porsche 997S-2005: Screeching noise from Engine
Hi,
I hope somebody will really help me as i don't know who to turn to.
There is really loud screeching noise coming from fly-wheel engine area. In my desperation i got it towed to a local garage. They said they isolated the engine by removing the gear box and then removed the timing belt and the nose was still there. They didn't remove the fly wheel.
I have upload the video of the noise looking from underneath the car on YouTube. Please have a look.
I can really do with some advice.
Thanks in advance.
I hope somebody will really help me as i don't know who to turn to.
There is really loud screeching noise coming from fly-wheel engine area. In my desperation i got it towed to a local garage. They said they isolated the engine by removing the gear box and then removed the timing belt and the nose was still there. They didn't remove the fly wheel.
I have upload the video of the noise looking from underneath the car on YouTube. Please have a look.
I can really do with some advice.
Thanks in advance.
06-22-2017, 11:16 AM
#3
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This noise only starts after 10mins or so from a cold start. The noise is still there when accelerating and shifting.
I only drove it only 200meters to a mechanic as i was worried i would damage the engine. Can it be engine related and it is possible i need to rebuilt the engine?
I only drove it only 200meters to a mechanic as i was worried i would damage the engine. Can it be engine related and it is possible i need to rebuilt the engine?
06-22-2017, 11:39 AM
#6
Race Director
It is a good chance the AOS has failed and the noise you hear is air being pulled past a seal (RMS or the FMS). The fact the noise continues a brief time after the engine is shut off is the air pressure equalizing between the inside and outside of the crankcase.
If I'm right I would expect with the noise present you or a tech would find it hard to impossible to remove the oil filler tube cap due to the excesisvely low pressure in the crankcase.
However, I would prefer you and the tech use a more "scientific" test/check to confirm the AOS is bad. There is a check that can be made that measures the amount of low pressure in the crankcase with a customized oil filler tube cap with a connector to which a vacuum gage can be connected and the low pressure measured while the engine is running at idle.
AFAIK Porsche doesn't publicize any numbers but others have found what a good AOS and what a bad AOS produce and have posted this. Pelican Parts has a write up on this.
The info there gives 4 to 7 inches of water for a healthy (Boxster) AOS. More is a sign the AOS is bad.
Here's a link to the Pelican write up:
http://www.pelicanparts.com/techarti..._Separator.htm
I didn't look for one for the newer models like the 997.
If I'm right I would expect with the noise present you or a tech would find it hard to impossible to remove the oil filler tube cap due to the excesisvely low pressure in the crankcase.
However, I would prefer you and the tech use a more "scientific" test/check to confirm the AOS is bad. There is a check that can be made that measures the amount of low pressure in the crankcase with a customized oil filler tube cap with a connector to which a vacuum gage can be connected and the low pressure measured while the engine is running at idle.
AFAIK Porsche doesn't publicize any numbers but others have found what a good AOS and what a bad AOS produce and have posted this. Pelican Parts has a write up on this.
The info there gives 4 to 7 inches of water for a healthy (Boxster) AOS. More is a sign the AOS is bad.
Here's a link to the Pelican write up:
http://www.pelicanparts.com/techarti..._Separator.htm
I didn't look for one for the newer models like the 997.
06-22-2017, 12:08 PM
#7
Rennlist Member
That seems to make the most sense and also doesn't seem to be related to the rotation of the engine, which is good! Equalization of the vacuum does make sense.
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06-25-2017, 10:51 AM
#8
It is a good chance the AOS has failed and the noise you hear is air being pulled past a seal (RMS or the FMS). The fact the noise continues a brief time after the engine is shut off is the air pressure equalizing between the inside and outside of the crankcase.
If I'm right I would expect with the noise present you or a tech would find it hard to impossible to remove the oil filler tube cap due to the excesisvely low pressure in the crankcase.
However, I would prefer you and the tech use a more "scientific" test/check to confirm the AOS is bad. There is a check that can be made that measures the amount of low pressure in the crankcase with a customized oil filler tube cap with a connector to which a vacuum gage can be connected and the low pressure measured while the engine is running at idle.
AFAIK Porsche doesn't publicize any numbers but others have found what a good AOS and what a bad AOS produce and have posted this. Pelican Parts has a write up on this.
The info there gives 4 to 7 inches of water for a healthy (Boxster) AOS. More is a sign the AOS is bad.
Here's a link to the Pelican write up:
http://www.pelicanparts.com/techarti..._Separator.htm
I didn't look for one for the newer models like the 997.
If I'm right I would expect with the noise present you or a tech would find it hard to impossible to remove the oil filler tube cap due to the excesisvely low pressure in the crankcase.
However, I would prefer you and the tech use a more "scientific" test/check to confirm the AOS is bad. There is a check that can be made that measures the amount of low pressure in the crankcase with a customized oil filler tube cap with a connector to which a vacuum gage can be connected and the low pressure measured while the engine is running at idle.
AFAIK Porsche doesn't publicize any numbers but others have found what a good AOS and what a bad AOS produce and have posted this. Pelican Parts has a write up on this.
The info there gives 4 to 7 inches of water for a healthy (Boxster) AOS. More is a sign the AOS is bad.
Here's a link to the Pelican write up:
http://www.pelicanparts.com/techarti..._Separator.htm
I didn't look for one for the newer models like the 997.
06-25-2017, 12:18 PM
#9
Burning Brakes
Most reports of failed AOS include the screeching noise you describe and also a lot of smoke out of the exhaust.. If the AOS is making this much noise, I'm surprised that you're not getting any smoke.
However as already pointed out in the thread, it is easy enough to test by attempting to remove the oil filler cap while the engine is running (so it is definitely a worthwhile test).
Here are 2 more AOS threads. Although the values for for 997.2, hopefully it can be of some help.
Good luck. Hope you find the problem quickly.
https://rennlist.com/forums/997-foru...-resource.html
https://rennlist.com/forums/997-foru...l#post13848924
However as already pointed out in the thread, it is easy enough to test by attempting to remove the oil filler cap while the engine is running (so it is definitely a worthwhile test).
Here are 2 more AOS threads. Although the values for for 997.2, hopefully it can be of some help.
Good luck. Hope you find the problem quickly.
https://rennlist.com/forums/997-foru...-resource.html
https://rennlist.com/forums/997-foru...l#post13848924
06-26-2017, 01:14 AM
#10
AOS and I did mine and everything else belt driven last summer. It's a PITA. You will shred your hands and curse the car. I did save a lot of cash though. Just a bitch to work blind and use wrenches blind....but very doable if you are spirited enough.
If you can't remove the oil filler cap while car is running that's the culprit.
If you can't remove the oil filler cap while car is running that's the culprit.
06-30-2017, 06:33 AM
#11
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Here's an update for you guys. I took your advice and had the car towed to a specialist. It was the AOS - It cost me £100 for the part and £200 labour. A little different to an engine rebuild that the original mechanic advised.
I would like to thank every one of you for your feedback, support and guidance for what was quite a stressful period whilst trying to sort this problem out.
I would like to thank every one of you for your feedback, support and guidance for what was quite a stressful period whilst trying to sort this problem out.
06-30-2017, 08:33 AM
#12
Glad to hear..just saw a boxter with same screeching and no smoke.. and it was aos..noy all cars smoke when aos goes.. best sign is the hard to take off oil cap..so much vaccum it doesnt want to come out..