atx.911

Since the weather has gotten colder, I noticed that my 996 03' has been making a noise when starting when the engine is cold. I am down in Austin tx so it hasn't been like north US cold.

It first started happening when I had it parked on a 60 degree incline and 32 degrees outside.

It sounds like it is coming from the alternator or one of the belts around the alternator.

Right when I start the engine, it sounds like something is hitting up against a belt similar to a rubbing noise more or less then the sound goes away after 2-3 seconds everytime.

After the engine is warmed up, it doesn't happen anymore on startup.

Anyone have similar experience or know what it could be?

atx.911

And it is not a high pitched whining noise - when I did a search I noticed a lot of posts for those saw like high pitched noises - that's crazy!

It is more of a deep belt rubbing noise just 2-3 seconds at start.

redridge

Sound clip?

nazhat

how many miles? has belt been replaced?

himself

As mentioned, a sound clip would be helpful.

FWIW, you should year my car start up in the morning - all loud and metal-on-metal clangy for a couple seconds. It made my skin crawl for the first few months.

-td

Pac996

At 60 degrees I'd imagine even the motor mounts could be near rubbing their limits of play or the airbox is hitting or binding on something when it cools down the the vibration of starting gets it shaking out of the being stuck to whatever position it was in when hot. Can we see a picture of this 60 degree incline?

brnrkm

I think that I know exactly what you are hearing. Mine does it sometimes too. Cold night, first start of the morning.

I think (hope) it sounds that maybe when the motor spins up and then down on start, the sprag clutch on the alternator is making noise.
My theory is that the motor and accessories spin up together on start and then the alternator doesn't spin down quite as fast as the motor.
Assuming that the alternator has a one-way clutch on the pulley (anyone confirm?) that is exactly what it sounds like to me. Kind of a buzz/whine/fine-ratchet sound, high to low (but not very low).

Loud enough to get your attention, with the windows up no less. Haven't noticed it when I park it butt in, but it's been warmer too.

As much as what goes on when this thing starts, I've about decided to ignore all the noises. This particular one though is such that it could be disturbing to some.

an 03' 4S 6spd with 84k miles

Brian

fpb111

disconnect the power to the aux air pump. Then see if you get the noise on cold start. It lives by your left knee when you are standing looking at the engine scratching your head.

atx.911

I'll try to get a sound clip, it's an 03 56k miles and belt never replaced.

AOW162435

Andreas

Byprodriver

Could be the IMS chain tensioner oil is bleeding down & chain is flapping around until sufficent oil flow pressurizes the tensioner enough to control the chain slack.

brnrkm

With our recent cold snap I had an opportunity to record a sound clip.
Also decided that my alternator pulley theory was pretty far fetched.

http://www.youtube.com/watch?feature...&v=02El-EUWJBQ

Is this the sound you have?

Brian

redridge

^^^ that sounds like a sticky starter plunger. My .02.

atx.911

That is exactly what it is. Here is the same noise on my car...that is exactly the same noise I get. (By the way, I stop and restart my car so you can hear the sound a cpl times)

http://www.youtube.com/watch?v=ZZXvdP4TCC4

http://www.youtube.com/watch?v=decfd5zCIDc

http://www.youtube.com/watch?v=y9cgnP5ilq8


Anybody have any idea what this noise could be?

Byprodriver

After hearing your soundclip I withdraw my previous guess. No new guesses but it sounds distinctive enough that a mechanic with experience with this issue should recognize it right away.