2009 volvo s40 t5, loud whistling while idling.
 

Hi all! New member here. I looked through the threads and didn't see quite what I was looking for. Ok so down to the problem.. a few months ago my car slowing starting making a light whistling noise when it idled. It's gotten very loud now. When we accelerate, it completely goes away. I know it has something to do with the Pcv system we just cannot pin point it. We took it to get serviced today (full tune-up, oil change etc..). I included photos of the receipt that lists all that was done to the car. We specifically mention the noise and the machanic said it was definitely the pcv valve. First of all it took them 8 hours, up until the last few minutes they were open. We couldn't tell right away that the whistling was fixed as it takes the car to warm up before we hear it. Obviously it started whistling on the road and is just as loud as before. We are not 'car people' but tried as best as we can to research online and we think it might be the pcv diaphragm. Does this sound accurate? We are really trying not to spend the $160+ to replace the whole system if it possibly can just be a small $20 part. Any help would be muchly appreciated. Also help finding part numbers or directing us to websites to look up the parts would be great too. Thank you so so so much again for any suggestion.
-sara
https://cimg2.ibsrv.net/gimg/volvofo...9e1b04c55e.jpghttps://cimg1.ibsrv.net/gimg/volvofo...b734c98934.jpg

The PCV system on these cars sits under the intake manifold and the standard R+R is to replace the oil separator (aka flame trap) and associated hoses that might be gunked up and not allowing the crankcase gasses to vent back into the intake. The quick test is to pop out the dipstick or open the oil filler cap when the engine is running - if the whistle goes away you know you have positive pressure. Another PCV system test is to pop a latex "surgeons glove over the oil fill and if it inflates with the engine running again you have too much pressure. If it sucks in or puffs in and out your PCV is ok. Two things to note - if your engine was really gunked up, the mechanic should have rodded out the ports in the block in addition to replacing the hoses and separator - if the car is really gunked up, the oil pan can be dropped to further clean the bottom end. If those quick tests don't stop the whistle, then I'd be looking elsewhere like the brake booster etc