Hello,

I posted a little bit ago I posted a message regarding a sound coming from the exhaust side of my '85 740 turbo.

To reiterate: there's a moaning sound coming from the exhaust area of my engine bay when the turbo goes from boost to vacuum. Mind you, it spools up fine, sounds like the good ole Garrett, but as soon as the meter leaves the yellow boost section and heads into the black, I hear a groaning sound that continues till the turbo has slowed down.

And it was suggested by some folks on this board that it's my compressor bypass valve. They said the little allen wrench bolts needed tightening, perhaps, or the gaskets need replacing.

However, as far as I can tell, neither needs doing. Those bolts don't move, and I can see no breaks in any of the gaskets.

But I've noticed that there're so many OTHER things on the valve: the nut at the top, a bolt at the bottom, some other things that all look adjustable. Is there anything else on the valve that would need adjusting to keep the sound from happening?

I hope it's something like that; it makes the most sense that this would be the problem, as well as the cheapest fix.

I appreciate any information very much.

Thanks,

vincent