ROE SCRATCHY WHINE IS BACK NEED HELP

[blackviper]

After removing the K&N heatshield the initial noise went away. Now, a day later a similar noise is back. I have actually recorded it. It is still most prevelant at 50 MPH. I went on roadtest with a BMW Master tech and after hearing the noise we pulled over. THe noise can be reproduced while power braking at 1750 RPM. Wih the hood open it sounds like it's coming from the S/C. When we got back to the dealer we popped the hood open check the S/C oil level and it showed about a 1/4 of the way up the window with foam accumalated on the top. After we let it sit for a few minutes, the foam went away and the oil level is just below half. I will be calling Sean this morning. Can you guys please provide any feedback? I see a nightmare coming.By the way, how do I attach a WAV file.

 

[stick]

sorry to hear that man, I think these engines just dont like FI. I hope things work out for you

 

[Prof]

put the wav file on photobucket.com then copy it here.

 

[Silverback]

Does it change pitch with engine RPM?

Does it do it only under boost, or does it make a difference?

I would suggest that you pull the inlet off of the SC and take a look at the rotors. I would not be driving it if they are going bad. After all, that material would be going through the engine. In fact, you should do this prior to driving it any further.

 

[blackviper]

Prof, Photobucket does not take WAV files.

Silverback, You can actually drive through the noise. I spoke to Sean this morning and he doesn't seem to think it's the S/C bearings. He said if it were, the noise would probably be constant. He did ask me to apply presuure to the aluminum piece that is at a 45 degree down angle behind the throttle body and see if the noise goes away. He mentioned that this piece sometimes vibrates, resonates or even sometimes comes loose.

 

[blackviper]

Here is Sean's response.

"Check the back cover to make sure it’s tight.

2mm allen key.

It appears that it happens at load transition / near 0 vacuum, which corresponds with when the blower has the most pulsation noise in the inlet.

Sound doesn’t travel through vacuum and is probably why you only hear it at the time you do.

Check the cover."

What do you think?

 

[Prof]

What do we think????

Sean designed, developed and hand built it...his guess is the best guess, no assurance that it is the only answer, but I would not spend time on anyone else's idea until I had fully checked out his input!

 

[blackviper]

Well I got home today and had a chance to give everything a good look over. I checked the cover as Sean requested and it was tight. I did tap on it and it is very thin aluminum. I did find a vacuum hose laying up against that same back piece. The hose is one of a few that come off the brake booster goes up and over the S/C and goes thru the firewall. Maybe that carries some of the resonance of the whine into the cab.

I also check the entire engine area and everything seems secure. I also checked all the pulleys to see if they were tight. They were. One interesting thing is when I put a wrench to the S/C pulley to make sure it was tight, I was able to turn the pulley. It actually slips on the belt and turns the S/C.
Is that normal?

I will roadest the vehicle in the morning and post the results.