Unusual Noise....?

[Bagzy]

An unusual noise has appeared on my Gen 1 Cayman S[8|]
It seems to be random.. only occurs at high speed and only some of the time.
It appears to be coming from the area in or behind the dashboard, maybe at the very rear of the front boot area.
I'm no acoustic expert....and can only describe the sound as non mechanical, but a wining screech that is high pitched, that disappears when i slow down.
Apart from the sound there appears to be no other noticeable effect on the car, its functions/driveability etc

Before i enquire with my OPC and take them for a spin for a diagnosis.....does anyone have any ideas or had experience of this?

 

[Richard_Hamilton]

I would start by looking for loose trim, or the windscreen seal, along the area at the base of the screen. A small air gap can cause a reed-like sound as the air passes through. If you find something that looks suspect, try taping it down with masking tape and giving it a test run.

 

[Bagzy]

Thanks Richard. I've already checked to see if there's anything loose etc and couldn't find anything wrong. Windscreen seal is fine......it doesn't sound like a noise that could be a result of air/air flow/air leak etc.

 

[Motorhead]

Always difficult to track down this type of noise source Adrian. Being speed-sensitive and high frequency, as Richard says it sounds more likely to be airflow induced rather than having a mechanical source. I'd check that the wheel arch liners and underbody panels are firmly secured. You may need to duct tape over the windscreen seal to confirm that it isn't the culprit. Other ideas:- Try fiddling around with different heater configurations - including recirculation - to change the ducting flap positions. Have you tried opening the window(s) to gauge: 1) if it's external; and if so 2) its intensity? Are you absolutely certain that the noise source is from the front of the car? Sound in an enclosed cabin can sometimes appear to be coming from a different location from its source. Jeff

 

[Bagzy]

Thanks Jeff, definately a difficult one but some good food for thought there, heater configurations/opening windows etc. Yes, i'm certain that the noise is coming from inside or just behind the dashboard/bulkhead area, and centrally. I'll do some more investigation this evening[]

 

[kasspa]

Hi Adrian, I had a similar sound last year & can only describe it like Richard has said, a reed like sound. At 1st I thought it was interference with a speaker but definately wind related & only starts around 80mph.... Strangely enough it went away for months but returned the other day so l'm now thinking plastic trim that has perhaps become harder with the cold weather..... Drove 2k miles in Europe in June at speeds rather higher than 80 with no sign of the noise...... Will watch your post for any developments and if I identify my noise will contact you Rgds Paul

 

[Bagzy]

Hi Paul, thanks for the reply. I've been out over the weekend with no return of the noise[8|] I'll just have to persevere for now, likewise, will update you with any news.

 

[Buddy]

I take it that you've checked wipers and wiper arms etc if the blades are dry or perished they can behave strangely

 

[Bagzy]

Hi Kevan, yes all fine there. The sound is definately coming from within the car, behind or around the dashboard area . I've spoken with Jon Mitchell at JMG and from experience he's almost sure the cause is the blower motor or ducting. He's also known a badly blocked pollen filter to cause the noise at the blower. My filter was replaced as per service schedule but ill check it out anyway along with the above.