Hi guys

This engine noise is baffling, was positive it was the air con compressor bearings. Loud rattling sound from around air con compressor on starting. Took the car to an auto electrician/air con specialist. A rare breed of man, spent 30 mins testing and probing, he said there was nothing wrong with the bearings. He tested on and off, under load and nothing. Also said all the belts and tensioners were fine. I told him it only happened when it was cold and lasts about 5mins. He said it could possibly be something with the exhaust, I have read on here about engine y pipe divider making a noise, can anyone give me an idea what that is all about. once the engine reaches operating temp no noise whatsoever. He didn't even charge a cent.

Tell me - where is this unique man! Service like this deserves recognition. Back to your pronlem - it is most likely the splitter in the exhaust headers. I had the same noise for years. Eventually it seemed to disappear. It was more like a buzz rather than a rattle.

Considering you first thought it was aircon bearings, and now think it is the "Y" pipe, two things that are far apart, tells me you really haven't tracked this one down too well.

Try the old stethoscope trick. Beats guesswork every time!

Even a simple thing like a short legth of garden hose can be used to narrow down where a noise is coming from....

When you start the car, if you hear the noise, shut it down, let it sit for 20 seconds and restart, let us know the result

Thanks Madmagna I tried that, I read it in another post. Turned it off and left it for 30secs, then turned it on again. It was still there. I'm trying to organize a mechanic and leave the car overnight, so he can start it cold and hopefully find it.
I did notice today that if the vehicle is in drive and foot on brake give it a little power you can hear rattles. Coming from the air con area. Hopefully someone can sort this out lol. Did try the stethescope and was positive it was the air con compressor, couldn't hear any other noises when i listened to alternator, power steering or tensioner pulley.

Is sounding more like the engnie pipe then or the pre tensioner is really stuffed.

Noise can transmit all over the place and make things hard.

Can you take the belts off and run it to eliminate the possiblity of it being the aircon/alt/pwr steer?

No Jimbo, I used to tackle anything on cars when I was younger lol. Now i'm old hands have trouble moving lol. I'm organizing it for next Tuesday MadMagna, one of the few mechanics I trust will keep it monday night and have a listen on tuesday morning. He did mention the exhaust but like you said the tensioner may be totally stuffed. Either way it shouldnt cost an arm or leg to fix.

I had a rattle coming from the AC compressor area as well, and took me a while to find the problem.
It sounds like your problem is sometime different to mine, but still, watch the video on my thread just incase and let us know if it's the same as what you're hearing on your car
http://www.aussiemagna.com/forums/showthread.php?t=103799

Noise can transmit all over the place and make things hard.

Checked the tension of the belts? They need to be really tight (compared to the older "V" belts), 10 Kg of force at the centre of the longest run should only move the belt 1 cm. If the belts are not tight, they flap about when cold at low RPM and the noise appears as resonances in other parts of the engine.

Also check that the mechanisms for the belt tensioners are seated properly. Tension on the adjuster bolt while tightening the belt tension can make the whole thing tilt over and the centre bolt (nut?) appears tight when it isn't. Back off the adjuster screw a bit, and check that the centre bolt (nut?) is tight. If it isn't tight, repeat the adjuster back off and centre bolt tightening until the centre bolt is tight, then nip up the adjuster bolt.

I have a noise like this.
Only happens when its cold and only really as I put a bit of load on engine up to around 1500rpm.
Will try the pretensioner trick

OK guys thanks for all the info. It turned out to be the air con, Mechanic said with age of the compressor might as well get a rebuilt one, trying to repair the old unit is like opening a can of worms. Have ordered a rebuilt at $385.