Squeak / chirp at low RPM - AOS related?

[John V]

My car (2000 Boxster S, 42,000 miles, 6-speed manual) has developed a chirp, or squeak, at startup, idle, and low RPM. It is rhythmic and varies with engine speed. It will happen in gear or out of gear, moving or not, but the engine must be running. I cannot replicate the noise by simply prying or shaking the engine. I cannot replicate the noise by pushing the car forward or backwards in gear with the engine off.

Here is a quick video that demonstrates the noise quite well.

Right click, save as

The noise appears to emanate from the left rear of the car. It is very loud in the driver's rear wheel well. Removing the wheel, it seems to be occuring near or above the head of the motor on the driver's side. I put a screwdriver blade on the valve cover with the handle end in my ear (cheap mechanic's stethoscope), and the squeak doesn't appear to be an internal engine part (good news).

I removed the front access panel and the noise doesn't appear to be coming from the belt area. Nonetheless I removed and checked the belt and it looks fine, and all the pulleys and tensioners spin freely and smoothly. It is unaffected by having the A/C on, and unaffected by me turning the steering wheel.

The interesting part is it appears to be much worse with the oil cap removed. I get moderate suction from the oil fill tube with the motor idling... not enough to suck my hand down painfully but there is a bit of suction there. I have a puddle of oil under the throttle body and there is oil in the AOS tube leading to the manifold past the throttle body. I get a bit of oil smoke on startup occasionally, but no CELs and no oil while driving. I have heard that the AOS failing can cause a squeak - does it sound like what is on my video?

Last bit of info - I changed out the driver's side spark plug tubes and o-rings last week. I cleaned that valve cover with solvent to get the old oil off of it. Is it possible this is related to that? I can't see how it would be, unless solvent got somewhere it shouldn't have.

Thanks for any help!

Edited April 28, 2007 by John V

[Chris_in_NH]

i don't know what the sound is, but it sounds like something loose/rubbing due to the engine vibration.

if you have oil around the TB and in the J-tube, you need a new AOS, period. i would not drive the car until you've replaced it. once a cylinder fills with (uncompressible) oil, that's it. you're done.

[John V]

i don't know what the sound is, but it sounds like something loose/rubbing due to the engine vibration.

if you have oil around the TB and in the J-tube, you need a new AOS, period. i would not drive the car until you've replaced it. once a cylinder fills with (uncompressible) oil, that's it. you're done.

Thanks, Chris - I will definitely replace the AOS.

But I don't think it's going to stop the squeak. :angry:

[evansaero]

Does it go away when the car is warm.? If so if you let it set to warm up does it go away or do you have to drive it for it to go away

Could it be the Trans?

[John V]

Does it go away when the car is warm.? If so if you let it set to warm up does it go away or do you have to drive it for it to go away

Could it be the Trans?

It does it warm or cold. Seems to be a bit worse when the car is hot.

I removed the serpentine belt and started the car momentarily. The squeak was still there. Therefore I don't think it is related to the pullies or multirib belt.

It certainly could be in the transmission but it would have to be on the input side as the sound it engine speed related. It is unaffected by having the clutch in or out. It happens in gear or out. I'm at a loss. I'm driving my other vehicle until I get the AOS in.

JV

[evansaero]

If you notice my squeak is also engine speed related. It is coming from the trans. I just haven't had time to take it in

Mine only happens when cold. Goes away after driving for a few mins. I have done all the same test as you. Belt, let engine warm up without moving,clutch,gear change.

Sorry I guess this doesn't help, but know that I feel your pain

Edited April 29, 2007 by evansaero

[986Jim]

A bearing is toast in either one of the idler pulley or an accessory pulley. I hear cars with that all the time, typically its the power steering pulley or the timing belt tensioner. In this case won't be the timing belt tensioner but quite likely one of the tensioner for the accessory belt.

Have you had your belt changed yet? If not pull it off and start spinning things to see which guy is the culprit then order a new one.

[John V]

A bearing is toast in either one of the idler pulley or an accessory pulley. I hear cars with that all the time, typically its the power steering pulley or the timing belt tensioner. In this case won't be the timing belt tensioner but quite likely one of the tensioner for the accessory belt.

Have you had your belt changed yet? If not pull it off and start spinning things to see which guy is the culprit then order a new one.

I removed the serpentine belt and started the car momentarily. The squeak was still there. Therefore I don't think it is related to the pullies or multirib belt.

It's not an accessory pulley.

Edited April 30, 2007 by John V

[986Jim]

Dang my bad, I missed that in your post. Thats very odd then. Unfortunately it sounds like you have eliminated all the small easy stuff, guess what that leaves... I have a sneaky suspicion that it's something inside the motor now based on it being louder with the oil cap off and not the accessories. Unfortunately I think you had better go into a qualified mechanic (Porsche Shop) or to the dealership themselves as I'm not sure there is much more anybody can tell you without having it on the hoist and really pin pointing the sound.

I could toss it up on my hoist at the shop, however I am neither local to you nor a "qualified" Porsche mechanic so that won't help you much.

[wvicary]

I had a noise very similar to this and thought it was coming from the A/C compressor....removed the belt and the noise was still there...... it turned out to be the oil separator.

[John V]

I had a noise very similar to this and thought it was coming from the A/C compressor....removed the belt and the noise was still there...... it turned out to be the oil separator.

I had the car on the alignment rack at the local VW / Porsche dealer and one of the techs said it sounded like a bad AOS.

I should have my AOS from Sunset in a couple days, so I'll know by the weekend if this is the problem or not. I find it hard to believe the AOS could cause this particular noise, but I've been (Very) wrong before.

[911-996]

I noticed this noise with my 01' s a couple of weeks ago, It hadnt been started in a while and for the first minute or two on idle it was there

Havent noticed it since luckily :)

[John V]

Well it wasn't the AOS. I replaced it (it certainly was leaking a large amount of oil into the throttle body tube - needed to be done) and the noise is still there.

[wvicary]

Hmmmm...... I've no idea then. Does it change pitch at all when the clutch is disengaged?

[John V]

Hmmmm...... I've no idea then. Does it change pitch at all when the clutch is disengaged?

Totally unaffected by the clutch being in or out, unaffected by gear selection.

It varies with engine speed and it doesn't happen (or it isn't noticable) above 3,000 RPM or so.

I'm going to check the engine mount next, which was replaced recently.

[John V]

Problem solved. One spark plug was just slightly loose. The air pressure rushing out of the spark plug tube past the coilpack seals caused the chirp. The plug was probably loose for some time, but I never noticed it because the spark plug tubes had oil in them and it probably muffled the sound or didn't allow the chamber to resonate.

Anyway, torqued all the plugs and I'm a happy camper!

[wvicary]

lol... well thats a new one. Glad you got it sorted.

[FrayAdjacent986]

Good find! I'm glad it turned out being something simple! Now get out there and drive that sucker!

[Baconaire]

Well its still good that you replaced the AOS anyway and cleaned it up nice. Must be running good.

Edited May 8, 2007 by Baconaire

[leeg]

Hi this is the first time i have ever written here! but i just wanted to say thanks a million in sticking with resolving your issue. I have had this noise for two months and its driving me crazy! I downloaded your sound file and its the same noise as mine down to a T! As soon as its daylight i will get out there and check the plugs, i am sure that will cure the noise! god its cost me so much time and money trying to resolve this noise.

Thanks again!

Lee

Silver 2.5, with my04 full upgrade!

[John V]

Hi this is the first time i have ever written here! but i just wanted to say thanks a million in sticking with resolving your issue. I have had this noise for two months and its driving me crazy! I downloaded your sound file and its the same noise as mine down to a T! As soon as its daylight i will get out there and check the plugs, i am sure that will cure the noise! god its cost me so much time and money trying to resolve this noise.

Thanks again!

Lee

Silver 2.5, with my04 full upgrade!

Glad I could help. Let us know if that was the problem. Loose plugs suck!

[Daryl80]

Hi All

Sorry for re-opening an old post, but I guess its better than starting a new one.

Anyway, went for a drive this evening, and went over some bumpier country roads. However when I returned back onto the highway, the noise that John V posted started occurring. Again the symptoms are the same (chirping increases at higher revs, after 3000rpm, exhaust note drowns out the chirp, happens at low idle, regardless of clutch is in or not)

I'm hoping its something as simple as the spark plug being loose, however as I'm a total newb, can somebody please advise on how I can tighten it. Reading in another post, I believe the instruction to change the sparks plugs are:

Safely Jack Car, support on Jack Stands

Remove Rear Wheels

Remove Plastic Wheel Well Liner in forward location of each wheel

Remove Spark Plug Ignition Wire

Remove two hex hed screws holding each spark plug coil in place

Pull gently on rectangular spark plug coil to remove

You'll be left with spark plug still in car, about 6" inside the outer edge of the motore

Remove and replace each plug.

Can somebody please advise at which step, should I tighten the spark plug. Also, I'm aware there is a torque limit, and that I shouldn't over tighten. Is there any tools, or advice I should use to tighten this up?

Appreciate any feedback and support on the matter.

Thanks in advance.

[czier]

I torqued mine at 22 ft lbs (as per spec), but they were new plugs.

[Loren]

22 ftlb. for new spark plugs

18.5 ftlb. for remounted spark plugs

[mrcheeseman]

My car (2000 Boxster S, 42,000 miles, 6-speed manual) has developed a chirp, or squeak, at startup, idle, and low RPM. It is rhythmic and varies with engine speed. It will happen in gear or out of gear, moving or not, but the engine must be running. I cannot replicate the noise by simply prying or shaking the engine. I cannot replicate the noise by pushing the car forward or backwards in gear with the engine off.

Here is a quick video that demonstrates the noise quite well.

Right click, save as

The noise appears to emanate from the left rear of the car. It is very loud in the driver's rear wheel well. Removing the wheel, it seems to be occuring near or above the head of the motor on the driver's side. I put a screwdriver blade on the valve cover with the handle end in my ear (cheap mechanic's stethoscope), and the squeak doesn't appear to be an internal engine part (good news).

I removed the front access panel and the noise doesn't appear to be coming from the belt area. Nonetheless I removed and checked the belt and it looks fine, and all the pulleys and tensioners spin freely and smoothly. It is unaffected by having the A/C on, and unaffected by me turning the steering wheel.

The interesting part is it appears to be much worse with the oil cap removed. I get moderate suction from the oil fill tube with the motor idling... not enough to suck my hand down painfully but there is a bit of suction there. I have a puddle of oil under the throttle body and there is oil in the AOS tube leading to the manifold past the throttle body. I get a bit of oil smoke on startup occasionally, but no CELs and no oil while driving. I have heard that the AOS failing can cause a squeak - does it sound like what is on my video?

Last bit of info - I changed out the driver's side spark plug tubes and o-rings last week. I cleaned that valve cover with solvent to get the old oil off of it. Is it possible this is related to that? I can't see how it would be, unless solvent got somewhere it shouldn't have.

Thanks for any help!