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I have a 2006 997.1 and I need some help from the interweb to diagnose a bearing noise.
Its very faint and I only hear when the AC is on, typically at idle or when pulling up to a stop light. It will last for a few seconds and then go away - and will immediately stop if I turn the AC off.
I first thought it was the AC clutch bearing. (My hypothesis was when coming to a stop the bearing would get thrown out of balance). I ordered a new one and was planning to replace it today. However when I pulled the belt off, the clutch bearing seemed fine. No play, no noise when I spin by hand.
Upon further investigation I think the noise might be coming instead from the alternator pulley or the upper belt roller.
Video attached here. You can faintly hear a bearing noise either from the alternator or upper roller, it almost sounds like a rattle. http://d.pr/v/UwNMT1
Im going to pull the belt and try to roll these by hand. However, I'm confused how/why engaging the AC could impact either the alternator or roller.
The pulley on ac comp would be turning all the time. When ac is on and comp in running the clutch engages the internals of the compressor. Possibly compressor going out. If unsure try using a mechanics stethoscope to touch the mounting bolt on idler pullies or the body of alt, comp, w-pump see what sounds the loudest...
Bruce - Are your referring to the noise in the video that kind of sounds like sticks being tapped together?
I have a very annoying sound when I engage my AC. I wasn't sure if the pulley itself could be replaced and if it could I was going to try that first. The compressors are pretty expensive. I could swear the dealer said it was one self contained unit. Where did you order your pulley?
Bruce - Are your referring to the noise in the video that kind of sounds like sticks being tapped together?
I have a very annoying sound when I engage my AC. I wasn't sure if the pulley itself could be replaced and if it could I was going to try that first. The compressors are pretty expensive. I could swear the dealer said it was one self contained unit. Where did you order your pulley?
Sorry I can't help otherwise.
@WhipE350 - Yup, thats the noise I'm referring to...however it seems to coming from my alternator pulley or upper belt roller on the left side of the engine bay. It does not sound like its coming from the AC compressor on the right side of the bay...unless somehow the noise echoes off the back of the air filter box.
Strangely, it goes away immediately when I turn the AC off. Is the alternator or pulley possibly under more load when the AC is on, thereby making the noise more pronounced?
I inspected the belt rollers and tensioner and all the bearings seem to be good. They are tight and don't run free when you spin them by hand.
I can't really tell anything by spinning the alternator pulley.
I read a few posts about people replacing the clutch bearing and clearing up any noises they had from their compressor. However, most reference the opposite issue hearing noises when the AC is NOT engaged.
The pulley on ac comp would be turning all the time. When ac is on and comp in running the clutch engages the internals of the compressor. Possibly compressor going out. If unsure try using a mechanics stethoscope to touch the mounting bolt on idler pullies or the body of alt, comp, w-pump see what sounds the loudest...
Thanks. I need to head over to Harbor Freight and pick one up. I can't tell anything by rolling the compressor or alternator by hand.
You will notice more noise with AC on, as it's adding Load, some suggest that the rollers get gunked up a bit and can make noise, some suggest cleaning them, but I don't think this is excessive, trust me, when you hear belt noise at idle you will know it, it comes on right behind your left ear with a window down (at idle).
I was having intermitted belt chirps, only way to duplicate at mechanic was to turn on AC. I am still having an issue after a car wash though, car makes a terrible belt shriek right after the wash, even though I am super carful to not get any part of the engine wet. I would love to hear thoughts on that one.
doesn't make any other belt noise otherwise.
When the AC is on and the compressor clutch is engaged, there is significantly more drag on the belt, which can add tension on any pulleys on the pull side between the crank and AC pulley.
A mechanic's stethoscope (as mentioned earlier) is a good tool for tracking down bearing noise if you can get the probe near the bearing without getting it caught in a belt. Just keep in mind that through a stethoscope, ALL bearings make noise at different levels and hearing bearing noise through the scope doesn't necessarily mean that something is wrong.
And, unless a bearing is about to fall apart, it's often difficult to tell that it is bad by spinning it by hand. If the belt is on and you're turning the crank with a breaker bar (as in your pic), you won't get enough speed to hear a marginally bad bearing make noise.
I took it by my local indy today for a quick look. They used a stethoscope and heard nothing out of the ordinary on any of the pulleys.
Mystery continues. Im going to put this one to bed and take the advice of my old Chang Jiang motorcycle mechanic in China "just drive it until it breaks...then I'll tell you whats wrong".
I have a similar sound, and the same symptoms. I thought, and still believe, it's partly from a bearing in the water pump. I ordered a replacement after hearing a bad water pump spinning on youtube. It sounds like i have another sound coming from the alternator. My diagnosis continues...we'll see if the water pump clears up any of the sound! 2007 997s with 46k miles.
Here is a post I found on Panameras that sounds similar. Looks like its pretty common and those owners seem equally stumped. A few replaced the compressor and one alludes to it being an issue with the clutch.
As I approach 50k miles, and my first 10k miles of 997 ownership, I'm on a mission to track down the 3 minor but mysterious annoyances I have with the car. This is the main one.
I spoke to an AC guru a few weeks ago who didn't think it was the AC clutch bearing. He said I would only hear that when the AC was NOT engaged, so it had to be the something in the compressor itself. Seemed logical but my indy listened to the compressor and said it sounded fine. He felt it was something in the cabin I was hearing.
After doing some more investigation I put my head down in the passenger footwell with the glove box open and it does sound slightly more pronounced there. Its really hard to pinpoint since it only comes and goes for 5-10 seconds.
So question is...what other components of the AC are located in the dash or frunk, that have some type of rotating bearing when the AC is turned on....?
My immediate thought is the AC blower fan under the dash; however this spins at the same rate wether the AC is on or off (I think).
I just started getting chirping belt noises a few days ago. Just dropped off at dealer for 40k service. And no I can’t do it myself as I’m parked in condo garage and I can’t do things like that. But in four years I’ll retire and sell condo and get a house with own garage and fiddle all day with my toys. I’m hoping it’s just the belt and pulley. It’s not chirping after it warms up. Just when it’s been sitting a while.
So I had a very similar sound, as i mentioned earlier. I had an unrelated issue that forced me to take my car to an indy for repair. During the repair they stated a bracket was bad, which needed to be replaced. i don't recall which one right now, i can check when i get home. That fixed the sound for me. I'll update later tonight.
09-10-2017, 10:45 PM
Replacing a bad AC clutch bearing
