spender

Greetings - my 2003 C4S has been making a squeak on cold startups (first thing in the morning and then when I leave the office) - but never on warm starts. I had it at the dealer yesterday, and they couldn't figure it out, but suggested that if I could leave it with them for a few days they could hook up microphones and whatnot and figure out where it was coming from - but I don't think it's really that complicated - it has to be a belt or a pulley bearing. It's coming from near the top of the engine compartment on the passenger (right) side.

My indy (not the dealer), when I asked them about the squeak (which it's been making for a while, although it does seem to be getting worse as of late), said it was related to the brake in the starter or something like that.

Anyway, interested in your thoughts and ideas!

Barn996

Check your front grille, sounds like a bird chirp. Don't really know, sorry.

Macster

Can't play the clip but when my Turbo was making a dry bearing sound from that same general vicinity the source proved to be a noisy idler roller bearing located next to the power steering pump.

But it could be any idler roller or belt tensioner roller bearing or even one of the accessory drives.

With the engine cold and off give the belt a feel. If you feel any sharp edges this is a sign the belt's rubbing an accessory drive pulley which is a sign there is sufficient bearing/shaft "slop" to let this occur.

That ain't how a healthy accessory drive system should work.

Then you have to remove the belt -- note carefully (take pics!) its routing and its direction of travel so you can reinstall the old belt (or better yet a new belt *once* the source of the rubbing has been found and fixed) -- and give the accessory drives a feel looking for the one with the most (any) play.

Odds are if it is an accessory drive it is the water pump.

However another source of the noise can be a noisy secondary air injection (SAI) pump which only runs when the engine is cold.

You might be able eliminate this by as soon as you note the noise after a cold start turning off the engine and then restarting the engine. My experience -- not sure this is consistent though since I only very very rarely do this -- is the SAI pump does not come on at the restart.

So if the noise is present at cold start but not present at restart and the SAI is not running then you know...

Or if the noise goes away concurrent with the SAI shutting off -- you have to be outside the car and have the engine compartment lid open -- avoid sticking hands anywhere in the engine compartment with the engine running! -- this a pretty good sign the SAI is the source of the noise.

I doubt the shop will use microphones.

If anything is used it will be a mechanic's stethoscope.

The car will be left to get cold and the circumstances of when the noise appears will be verified and then allowed to occur while the car in on a lift and in the air and techs will be under/around the car to pinpoint the source/location of the noise.

Often the source is not obvious and it takes some listening, eliminating where it is not coming from, and the consensus formed from the input of several techs.

Sincerely,

Macster.

spender

Hi - if my embedded video doesn't work, try this one:

https://vimeo.com/51775214

I guess I should mention that it just squeaks once, and then that's it.

street rod

Yours doesn't sound like the SAI. They have a whine like a table saw. Ask me how I know.

txhokie4life

Starter??

Not disengaging the solenoid?

mike

fpb111

Pull the belt and then cold start. No noise = check all of the accessories for loose/tight/binding/freedom of rotation. If all seem ok replace belt with a new one.
Still noise, check AOS at cold start.

Pac996

I didn't see any mice hopping and running away so maybe its the belt since that cheaper.
My old engine had the chatter when first snapping it out of sitting around. If your car has been sitting around maybe the belt is getting a scrub-in to get rid of dryness.

gprosser

my 2002 996 4s made this noise for the first time this morning. also cold start to get it onto the driveway for a clean. be interested to hear if you discover the cause.

Laura

Check your spark plugs, Make sure they are all tight,.

Macster

Clip complains about my browser being out of date.

Anyhow,

For a single short squeak upon cold start my WAG would be the serpentine belt is just old or old before its time and slipping a bit. It could be helped by a dragging idler roller bearing or tensioner roller bearing even an accessory drive that for some reason requires extra effort to spin. A water pump comes to mind, of course since these go bad more often than the other accessory drive systems, but each accessory drive has to be considered and checked.

A sign perhaps that an accessory drive is acting up is if the belt has any sharp edges which comes from an accessory drive with play that allows the belt to mistrack and rub against the accessory drive pulley that is on the problem accessory.

None of my cars has ever done this initial squeak upon startup -- with one exception which I cover below -- even though both sit outside and sometimes even in bad (rain) weather.

The exception is the Turbo belt squeaks when I start the engine after washing the car. The belt is obviously slipping - though it does not squeak the whole time just very intermittently for a few moments until the belt/accessory drives lose the water. I know the belt is slipping from the way the engine behaves as the load from the accessory drive drops/climbs again as the belt slips then grips.

There are other explanations possible too.

It comes down to a pro tech either recognizing the source of the sound because he had heard this and fixed its cause before or tracking down where the noise is coming from by reproducing the noise with possibly other techs present since it is a brief noise.

One might focus on the accessory drive area while another might be near the starter.

Sincerely,

Macster.

swepersson

I have had the same sound for 2 years. Only appers when it´s cold outside. Dosn´t get worse so i have learned to accept it.

spender

So, I had the car in at the dealer for the last 2 days, also to look at other things. The shop guys started the chase the noise - but were unable to find it. According to my bill (they didn't charge me for the time, however, which I thought was nice), they installed microphones on the fuel injectors, fuel rail, cam position sensor, oil pressure switch, exhaust brackets and suspension components - but none of these positions isolated the noise. They also noted (as I told them) that the sound disappeared on startup once the car was warm.

Personally, I really think that it has to do with the belt or something that the belt is turning...

spender

And the winner is -- LAURA! When I brought it in to my Indy this morning, he found that one of the spark plugs was loose and very carbonized, as was the spark plug tube. He also found that my belt had some damage (cracks and a groove had worn down). He hasn't restarted it yet, but he's pretty confident this is the cause.

Now, the LUCKY part of the story is that while he was doing this, he noticed the water pump had a small leak, and he will be changing that as well. It is a small leak that I would have been unlikely to notice. Given the apocalyptic stories about 996 water pumps that are circulating thanks to that Excellence article, I am feeling pretty lucky right now!

Perhaps the startup squeak was some kind of built-in diagnostic warning me of the imminent failure of the water pump? You never know with those Germans, they over-engineer everything...

Barn996

Glad to hear that the problem is solved. Good catch on the water pump as well.