Chirping noise from engine on 996

http://youtu.be/575JKEOZBNc . Hi, I have read through the forum to see if anyone else has the same or similar problem but as yet I am at a loss and so is my local OPC. Above is the address for the video of the chirping noise and apologies for the erratic videoing. This chirping noise has been going on for months as it was initially suggested by my OPC that it sounded like a pulley on the water pump. Today it went in to the OPC for what was supposed to be a water pump replacement but alas they confirmed this wasn't the problem and they were at a loss to diagnose what other than it was coming from the left bank side of the engine. They ruled out IMS, AOS and Serpentine and suggested that until they got inside the engine and even then no guarantees, would they no what the problem is but so far its a head scratcher. I should note that the noise stops on long runs when the engine is really up to temp and there are no diagnostic issues, it doesn't use much oil and touch wood, runs sweetly. Any help suggestions would be greatly appreciated. Thanks, D

AOS..!!!!!!!!

AOS ruled out

Suggest the usual test. Remove the belt & run for short time; if noise is gone, rotate turning components by hand for excess play, resistance, etc. GL with fix.

Done all the belts, AOS and IMS tests and the OPC has ruled these out. New suggestions have been a loose spark plug or exhaust gaskets so will take back to garage to check.

does the noise vary with engine RPM, or only occur at idle? Sounds silmilar to when the idler pulley on mine started to go. It eventually turned into a aweful grinding noise that sounded like my motor was self destructing. I'd take it somewhere else to get another opinion (and don't tell them what's been looked at already) before tearing into the motor.

Does it go away when the clutch is depressed? Sure sounded louder on the drivers side by the exhuast manifold. Lose plug.

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Assuming the OPC's correct in eliminating the source of the noise is belt or accessory drive related, then my money is on an exhaust leak. A not too close second is a loose spark plug. In the case of a plug the noise I believe would be present all the time, while an exhaust leak can go away if the hole closes as the exhaust system heats up and the hole (probably a crack) closes. A suggestion: You really should arrange to get the car in the air safely and arrange to get under the car with a stethescope (or with a mechanic who has one) and give a listen to narrow down the source of the noise. Now not only do you use your ears, you use your nose to detect any smell of a leaking exhaust. It may have a bit different odor than the exhaust from the exhaust outlets, depending upon where the leak is and how severe it is. You can see if you can spot the leak by using a feather. Buy a feather duster and use a feather to run it along side but avoid touching the feather to the hot exhaust and see if you can spot the feather react (flutter?) when it passes through/by the exhaust leak. If you touch the feather against the hot exhaust just toss it and grab another. (As an aside: to find leaks in high pressure/high temperature (hundreds of PSI and hundreds of degrees above boiling) steam piping such as are found in ship propulsion systems instead of a feather a wooden broom stick is used. When the broom stick is passed through the leak the steam cuts through the stick like a band saw blade.) But before you do the feather test you need to get the car in the air and pinpoint as close as possible to where the noise is coming from. You might get lucky and find the source without having to use a feather. Sincerely, Macster.

For a new one I thought maybe a motor mount till I listened to the video. Since the noise increases "when the vlave covers are viewed" it made me think uh oh miners trapped in thee trying to pick axe their way out. But trying to think easy fix it could still be the motor mount <crossed fingers>. Just because the video shows the valve area doesn't mean it isn't reflecting off of parts in there or noe being transmitted through metal paths. My seat of the pants estimate of rpm and valve activation tells me its 700rpm/30=23.3 intake or exhaust manipulations per second. Not like that matters to a gummed up or collapsing lifter. Since it sounds like a chirp there is exhaust bracket loose hint hint, internal exhaust loose instead or rattling its rubbing its dry metal chirping, and plain old proof the end of the world really is coming this winter I'd go simple with the engine cold checking header bolts and exhaust for tightness by first trying to move then trying a slight tightening of each and every bolt you can get to. Even the hangers. Good luck with it not being internal.

The frequency of chirp suggests accessory belt, idlers or bearings in generator, pump, A/C or servo. How did they rule those things out?

Was this ever sussed out? I have a similar albeit less prominent noise from the same spot. It goes away after warm up etc. I just had the aos replaced less than 1000 miles ago.

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Ian, have you tried running it briefly with the belt off? If no belt = no squeak, it's an accessory or idler pulley.

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Possibly the coolest thing I've read all week...

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No, I haven't tried that. There seem to be mixed reviews on running the engine without the belt on. I am thinking of doing the plugs, maybe racking it and use a stethoscope to pinpoint the sound. What are your thoughts on running it without the belt on?? BTW- thanks for the response!

Run with belt off for a very short time, because of coarse you'll have to water pump etc.,,

Running with no belt should be done VERY briefly...but if your squeak is constant with the belt on, it should only take a few seconds to verify whether it's present with the belt off. If it doesn't squeak when beltless, further troubleshooting can be done with the engine off... Spin each accessory/pulley by hand to figure out which one is squeaky...

I have the same sound...took to my local dealer to investigate/do a post purchase inspection. I asked how much a belt change would be (ever though its very easy) and they quoted me a modest $150 installed...including the belt, so they did it. The squeak has not gone away. During the inspection they noted the oil boot was ripped (cheap part, I think about $20) plus 2 hours labor...they did the change. Squeak is still there. (also did front upper control arm, I wouldn't do this myself, either way). Anyways, I'm sure they've looked at the AOS and didn't note that, could it really be as easy as a spark plug? My squeaking sounds 100% like the OP's, it only does it at low RPM/idle over 1,500 rpm it stops.

It COULD be a spark plug, but the fact that it goes away completely makes that seem less likely to me.

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Why didn't you let the dealer techs diagnose the source of the noise? I can tell you that rarely is the belt the source of any noise. But the belt should be changed if due on time or miles, regardless. I listened to the clip again and after having heard something similar from my 996 Turbo a few months (or more) back my WAG would be the noise is an idler roller bearing. But there have been enough cases of a loose plug that I couldn't dismiss that out of hand. That is none of my cars has had a plug go loose but other owners have, a few at any rate. When were the plugs last changed? Are they due to be changed again? If the idler roller bearing is the correct diagnosis you can confirm this by starting the cold engine without the belt. I assume though the noise is present at cold engine start? If so then this test at least lets you know something with the accessory drive is the source of the noise. If the noise is still present with the belt removed, then a loose plug, or possibly an exhaust leak is the source of the noise. If you do the engine start with the belt removed be sure you take pics, make a drawing of the proper belt routing and note the belt's direction of rotation so you can afterwards install the belt back exactly the way it was installed before. Added: Here's a clip of my Turbo making noise that proved to be from an idler roller bearing. View My Video I have two clips. This is the 2nd one. I mention this because the first clip I took from the very start of a cold engine start and the noise was not present. However, it didn't take very long, 15 to 30 seconds, before the noise appeared.

Here it is a couple years later and I had this exact same chirping noise on my 2001 911 996 and it happened to be the furthest rear drivers side spark plug had backed out and was loose. I changed all six plugs and coil packs as part of my 60k service along with the serpentine belt. Found this low mileage gem last fall when the original 74 year old owner traded it for a new 2016 911 because she was done using a manual transmission. My win!

I have experienced a similar sound when cold and idling. My guess is that the noise is less than 30 hz, doesn't seem RPM related, and gets louder when the AC is engaged. I have recently had the IMS, clutch, and water pump replaced recently - and the sound is still there. I did the belt off experiment and did not notice the noise. Also did a stethoscope probe and couldn't find a piece close to the noise. Coincidentally, the sound got significantly louder and more persistent just before the water pump went up. We were using the AC extensively, the water pump failed at a bad time, and the noise has me worried. My current guess is that it is in the idler pulleys, or ???. 2004 C4S with 110,000 mi. Runs like a champ and uses no oil between 5000 mi changes. Oil has always been clean between changes.

Well, the good news is that it doesn't reproduce with the belt off. As long as this is accurate, you know that it's not an internal issue. Since you have had the water pump replaced, the list of suspects is now everything else driven off the belt: alternator, air conditioner, power steering pump, idler pulleys, belt tensioner pulley. "Louder when the AC is engaged" seems to point to the air conditioner compressor, clutch, or bearing. When the AC is not on, the clutch makes the A/C compressor a very expensive idler pulley; when it's engaged, more stress is placed on the compressor pulley; a failing bearing seems like it would behave as you describe. With the belt off, is there any play in the AC pulley? If it wiggles side-to-side, the bearing may be shot.

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Chanel, I squeak with my belt on or off. But I agree, no one should run around with their belt off.

JRB37 Spark plug check to identify for a loose plug! I wouldn't have thought it was that, and just knew for sure it was an exhaust part touching and metal on metal chirp or the idler pulley or water pump that was chirping. The fact that it wasn't missing or running rough and did it with noise only at idle or with little gas given, I don't know how it wasn't running like crap? Mine was literally almost backed out into the coil pack with maybe a quarter turn from being able to pull it out! Just glad it didn't damage the threads so when I replaced it all was good. Both back plugs are a beast to get to and torque unless you remove the wheels and have it up in the air with some things removed. You can do it without doing that if you have small arms, hands like me and the right extensions, etc. I would give the plugs a check! I will do my own and not trust them to a shop cause that's how they ended up loose on the rear two spark plugs! Good luck!