Need estimate to replace the crankcase breather? Loud whistling noise f-engine

Check the crankcase breather hose under the manifold, near the power steering pump area. This is a common problem where the hose splits and makes a whistling noise. You may need a flashlight and a mirror to see it.

I had same problem. You have to replace the crankcase breather also called... breather box, flame trap, oil trap. 2 different Volvo dealers quoted me $800 and the other $1350. Go to a independent Volvo mechanic. I got mine for $450 installed. The part in not expensive, but the labor is around 4 hrs. They have to take apart a lot of the engine to get to it. If you don't have it fixed, it can cause your seals to leak.