I had the same problem with my 2007 V70. it appears I had a banjo bolt that was slightly longer than the original.

i cleaned the original and installed it. Problem solved.

if you lift the oil fill cap and feel a strong vaccume, it is the flame trap or Pcv system. this soln also stopped an oil leak at the cam seal.

I put the Cooper CS4 on about six months ago. I am happy and like you more concerned with noise but also cost. In GA we need good wet weather traction and this performs well on my V70. Cooper does not sell to the oem market and because of that, does not have to overcharge in the replacement market. ...

I had a problem when in gear, but not in park, with a flux in the idle. It took awhile to determine the PCV system was clogged. The indi dealer felt a strong vacuum when opening the engine oil cap. That was the hint to him. This was about 100,000mi. I also began cleaning the throttle body every 10K....

This car has 110K and the ac has begun to cycle quickly. The charge is between the 25 psi and 33psi as needed. I read several posts regarding the shim which keeps the ac clutch in the proper position. Rather than remove a lot of parts to reach the ac compressor, I used the "Getto Shim post"...