Winterreise

As described in this morning's video that I made, my C2 is making a little noise for about 1 minute total when starting cold. One thing I forgot to mention in the video is that one of the chain tensioners was replaced by ROCS in NJ last year along with a new coolant reservoir and cap. Being the 5 chain engine design (M96 Mk1) I don't know which tensioner it was.
Please have a look at the youtube video and thanks so much in advance for your comments.

Bob
https://www.youtube.com/watch?v=YlG-...ature=youtu.be

996_North

Is it just a ticking noise that goes away? Sorry your video is 6 minutes long, can you indicate the time the noise starts?

Ahsai

That's a very nice video with the detailed intro. A few observations
- your battery voltage looks quite low at ~11.5v but the alternator looks good as the voltage jumps to 14v once the engine is running
- there seems to be a yellow warning light ON?
- the SAI pump fan noise was quite obvious but that's normal
- there is some rattling bearing noise, which sounds external. You can remove the serpentine belt and hand spin each bearing and pulley to check for any free play and bearing noise. Could very well be the water pump or one of the idle pulleys, or the aternator. Can also unplug the SAI pump (so it won't drown out other noise) and run the cold engine with the belt off for a minute or two to see if the noise is there.

Ahsai

Just fast forward to the 3 minute mark.

996_North

I would agree that the rattling sounds to be external and maybe a alternator or pump bearing.

Hurdigurdiman

I have the same year and model with almost 74000 miles on it. I do all my own DIY apart from dropping an engine or gearbox. At first as you got the camera nearer to the engine I could hear something different to what I hear. Kind of a clack/clicking sound. To me a loose pulley sound or maybe a chain slap. This I am told is normal for a cold engine. Then as mine warms up it goes away as yours does. .. Again you have the same thoughts as I do. Maybe the water pump pulley. Remove the belt and try all pulley's. I never heard or felt a loose pulley on mine. I had seen the smallest of water drip onto the floor under the pump as the car cooled down. Therefore I changed the pump and thermostat. No drip afterwards. On cold start, same noise as always which quiets when warming. I am told on rennlist this is normal. I always let the engine warm for at least 5mins. Sometime even 10/15 minutes winter and summer. I have the original IMSB double race bearing. Not that THAT matters in this case. Just saying. Lets put it this way. Mine is louder when cold than it is when warm/hot so I would not worry about yours. I also keep my eyes on my gauges and ears pricked for any changes to the normal. My answer to you in one. Don't worry. It's normal but keep those ears and eyes open anyway. Safe driving and real nice looking car. 

Winterreise

Hello all:

So, I finally took some time to do a few diagnostic tests to see if I could isolate the source of the noise. I removed the air intake, bought a 24mm wrench and loosened the tension pulley, then removed the accessory belt. I spun all of the pulleys and all of them were smooth and quiet, including the water pump. I then started the engine (cold) with the belt still off, let it run 15 seconds before the clacking noise started as before. The car has had chain tensioners replaced in the last two years, not sure which ones but two of them had been done. The PO was probably trying to source the problem as I am. As explained earlier, the IMSB is one year old, an LN dual row. The original bearing was fine...
So, I am thinking chain slap noise until the tensioner involved fills with oil and stretches the chain taut. I have the M96-Mk 1, so there are 5 chains in this version. After one minute, the engine is quiet. The other thought is that one of my CATS is rattling. Tonight I will use a rubber mallet and tap on them both to hear if there is a different resonance between them. No CEL, no oil pressure anomaly... All normal and functioning beautifully except for the cold start noise.
All suggestions welcome and appreciated!

Bob

Ahsai

The video is no longer available?

Winterreise

No, to save my own space, I took it off

silotwo

Didn't listen to the video but as far as a suspect cat, I don't think the rattle will go away as the engine warms up. I had a bad cat and the rattle would appear whether the engine was cold or hot.

Rubik

That's what I thought. Why would the noise from the cat go away. But I hope is it's not the OPs other suspect culprit... yikes!

Winterreise

I am aware that many 996 owners have this quirky issue with engine knocking-pinging-ticking sound when those engines are cold. The Porsche Service manager in Rochester New York, where I'm from, says that these first-generation water cooled engines make a bit of noise until the oil circulates and the oil pressure activates the tensioners. So, I'm just not sure if ignoring this is appropriate or not.

Ahsai

I can not longer check your video but based on my post #3 at the time, I don't think you should ignore it. Oil circulates almost instantaneously at start up, at most a couple of seconds. Your noise is way after that if I remember right.

Winterreise

Yes even in the warm weather now, I'm hearing some artifact type noise for 45 seconds to one minute when the engine to start a cold

Ahsai

Not normal for sure. I think your dealer is not willing to diagnose it for you.