Strange loud knocking type noise from engine bay when AC activated

[CDN_135i]

As the title says I am getting some strange loud noises from th engine bay when AC is activated. Do our cars normally produce an audible difference in engine noise when AC is on?

I will post a video probably tomorrow.

Thanks.

[alvitdk]

Originally Posted by CDN_135i

As the title says I am getting some strange loud noises from th engine bay when AC is activated. Do our cars normally produce an audible difference in engine noise when AC is on?

I will post a video probably tomorrow.

Thanks.

Absolutely, the clicking noise you hear is the compressor clutch. sometimes the rpm will go down a bit as well, not much on my bimmer but on all te other cars I had.

[CDN_135i]

Ok so it definately isnt AC related. I met someone today that says he thinks it's the pilot bearing. Have a listen and let me know what you think.

http://s1153.photobucket.com/albums/...t=4a1ec1bc.mp4

You will notice at the 39s mark or so my wife presses the gas and it goes away until the engine rests at idle again. I also had the clutch stick half way today while driving.

Now here is the thing, the car sat and cooled for a few hours and it went pretty much completely away?????

It goes from sounding like a diesel to back to normal and the only thing I can think of is that after some spirited driving it was worse so im assuming that is a symptom.

[RimasRS]

Originally Posted by CDN_135i

Ok so it definately isnt AC related. I met someone today that says he thinks it's the pilot bearing. Have a listen and let me know what you think.

http://s1153.photobucket.com/albums/...t=4a1ec1bc.mp4

You will notice at the 39s mark or so my wife presses the gas and it goes away until the engine rests at idle again. I also had the clutch stick half way today while driving.

Now here is the thing, the car sat and cooled for a few hours and it went pretty much completely away?????

It goes from sounding like a diesel to back to normal and the only thing I can think of is that after some spirited driving it was worse so im assuming that is a symptom.

If it's only when AC is on. My guess would something is not right with your AC compressor maybe lack of oil and you can hear compressor pistons.

[CDN_135i]

FYI it was a flywheel dowel pin that was loose.