Very strange low whistling buzzing noise

[Jimbob]

My Williams has developed a very strange whistling / buzzing noise which starts at exactly 3500 rpm, and onwards through the rev range. It only does this after it has been subjected to a burst of hard acceleration (if driven gently its normal above 3500), then it does it all the time before going away as quickly as it came. But here's the odd bit. The sound seems to come from the front passenger footwell!!!! It doesnt seem to come from the engine, as outside the car you cant really hear it.... No loss of performance, just the whistling / buzzing sound. Its totally related to engine speed and not the transmission as if you dip the clutch the noise goes with the revs. Any ideas?

[AmDaMan]

weird mate, double check it's not electrical interference being transmitted through your speakers.

[Jimbob]

Yeah, that was one of the first things I thought of. I even went as far as to disconnect the speaker but it still did it!

[MatBrown]

Do your heaters work?
Cos it sounds like you have a blockage somewhere.


Mat.

[Allan]

yeah could be a leaf or somthing similar, i remember summys RT used to do it when you booted it hard :D

and also i have heard his williams do it a few times too :D

Was just more of a whilstle then anything else, kinda like if you have a blocked nose and try and blow out :D

[Jimbob]

Tried the heater out, seems fine! Only thing I can think of is a split or perforated vaccum hose, but the sound is too far back and I cant see any damaged hoses... Its still doing it so may get it looked at over the next couple of weeks.

[MatBrown]

Check the hose going to the heater matrix for a restricter valve.
If it has one, take it off and reverse flush it.


Mat.

[Jimbob]

...will try that today.

[Daz0371]

Check the heat shielding around the cat area if you still got it on, mounting screws came loose on mine and it made a noise like you said after about 3500 rpm

[scubaman44]

Mine does the same, only within last couple of months i've noticed it. Mine does this at 4000rpm tho. Same noise as you have, driving it above 4k the noise becomes progressively louder, then if I slow below 4000rpm it fades out.

Cruising at 80-85 in 5th the noise is constant, a whistling/buzzing sound. Slowing down it goes.

I have posted on cliosport and they thought Heater Matrix but wern't sure. I'll ask craig on fri as i'm having afew bits done at APD. I'll let ya know if I sort it.

Steve.