Have a 2004 S60 with 185k miles, recently had oil pump seal replaced to correct oil leak. Car ran fine for several weeks, then developed a sort of howling/ whistling noise at idle and seems to labor at idle. Noise is not present while driving.

Had my favorite Volvo indy listen to everything, and it checked out OK. OBD posted a P0420 Cat code, which indy thinks is unrelated. We are stumped.

Ideas?

Thanks in advance,
Greg
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Greg Caggia '93 240, '93 940 & '04 S60

185K miles is a bit over due for PCV maintenance. The best thing you can do is ensure you are using full synthetic engine oil.
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My back feels better when I sit in a Volvo seat

Related: 2000 V70 SE with 207K miles

Since first oil change, car has always been filled with Mobil-1 10W-30 full synthetic; and regular oil changes.

There are no signs of PCV trouble and/or crankcase overpressure including weeping oil out of filler cap area or pushed up dipstick; but, then again that's high mileage for PCV that's never been serviced.

Options as I see it:

1) Keep a close eye out for PCV symptoms, or
2) Change out the PCV with new parts? (and at least a day's work!)

btw, five speed AW-55 gearbox fluid changed out every 70K or so with Mobil 3309, still shifting and running well.

Thanks,

Does the howling noise at idle diminish if you crack open the oil filler cap while it's idling/howling? That's what mine (non-turbo) did when the oil trap diaphragm ruptured.

Chris,
You nailed it. When I pulled dipstick, the noise disappeared.

Indy had to remove intake manifold to get at the PVC air box and had to replace whole unit. Cost - $110 for parts plus 3 hrs . Car is running fine now.

The unit was pretty plugged up - any idea on how to service it and keep it clean to avoid future occurrence's in future Volvo's? I miss the old flame trap on the 240's.
Greg
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Greg Caggia '93 240, '93 940 & '04 S60