My '87 740 turbo is noisy anywhere from no boost to full boost. I rebuilt the turbo once and the noise started which sounds like a flute. I then purchased a new center cartride that was vsr balanced and also replaced the turbine housing and exhaust manifold because of cracks. It is still noisy. I have taken all the large diameter intake hoses off of a another 740 and put them on my car and it is still noisy.
The cbv valve was checked and also bypassed once for checking. Any ideas out there?
Thanks