2008 - noise changed after flame trap replacement

[smitty]

The car started making the whistling noise which eventually became an intense kazoo sound, and it threw CEL codes 0171 and 0174. Yesterday I replaced the flame trap (thanking my lucky stars it wasn't an earlier model where the dang thing is buried), which took all of 25 minutes. I checked the old boy, and sure enough, the diaphragm was ruptured.

Fired it up and cleared the codes, then took it for a test drive. Within a minute the CEL lit up again with the same codes, but after I cleared them again they didn't come back. Then after a 20 minute drive, when parked at idle there was a new noise. This is more of an intermittent huff or cough, about 1 per second, which ceased when the dipstick was pulled or oil cap opened.

Any ideas? For the life of me I can't find any schematics for the 2008 and newer flame trap or crankcase ventilation system to see where else a problem may lie. The crankcase vent system was pretty easy to understand on the old red blocks - not so much now!

[hoonk]

when parked at idle there was a new noise. This is more of an intermittent huff or cough, about 1 per second, which ceased when the dipstick was pulled or oil cap opened.

When a PCV box goes bad on the 3.2 you get too much vacuum in the crankcase, and you get noise from air being pulled past the rear engine seal, and the noise goes away by letting air in the dipstick or oil cap.

Same problem with "new" pcv box - what brand, where did you get this "new" part?

[smitty]

When a PCV box goes bad on the 3.2 you get too much vacuum in the crankcase, and you get noise from air being pulled past the rear engine seal, and the noise goes away by letting air in the dipstick or oil cap.

Same problem with "new" pcv box - what brand, where did you get this "new" part?

No, slightly different symptom - distinctly different sound. Official Volvo branded part from FCP Euro.

[hoonk]

You can measure the vacuum/pressure in the crankcase. Should be 0 to a slight vacuum. (simply remove the dipstick and attach a pressure/vacuum gauge to the tube)

[smitty]

Well, maybe it was just the new diaphragm settling in, or a slug of oil that needed to be digested. After 2 days and 50+ miles of mixed driving, the new noise has not returned. All is well for now.