I know there are a ton of these but none seem to be having my problem. I have a loud Whirring noise coming from my drivers side under the engine. It is not affected by pulling the oil dipstick or removing the oil cap. I have a 98 v70 turbo AWD XC. It has 179k. I experience no loss in power while the sound does get louder and then quiet at about 4500 and change pitch slightley with RPMs. There is also a P0442 code being thrown every once in a while which I clear commonly (not the gas cap). The sound is at start up and is there the entire duration that the car is on, whether idle or under load or driving or not driving. Also the interior lights have started flickering (very sparingly and not for any obvious reason). Everything but the P0442 code just started after I turned my car on after a quick trip to the quickmart by my house.
Any ideas would be super helpful! Thanks!

 

The P0442 is related to the evap system - likely a hose is leaking. Check Youtube for the vid on how to inspect the J-tube (a common issue with V70s) - its in the rear by the charcoal cannister. As to the noise, I'd suspect either your hearing some turbo whine or the air pump - (Google "V70 SAS"). Its also possible it could the the idle air valve vibrating or the vacuum pump but they make less of a whine and more of a buzz. Still you should probably listen around to the alternator and power steering pumps as well as the drive belt idlers and timing belt idlers/tensioner. Does the noise change if you put a load on the alternator (headlights/blower/rear defrost)? When you turn the steering wheel while parked? Does it get louder if you remove the timing belt cover? Try taking a section of hose (ie garden hose or fuel line), put one side to your ear and listen around to various components to see if you can find the source (including relays). The flickering lights are a concern - that's either a connection problem or your alternator/voltage regulator or a relay.

 

The sound doesnt change at all when a load is applied to alternator. It changes pitch as the RPMS go up if im driving or in park. Also havent tried removing any covers yet but it is coming from the drivers side, so the side opposite all the pulleys and the alternator and water pump. the side by the air filter housing. it sounds like it is coming from between the air filter housing and the engine, but under the housing.... its very odd, and it is a very loud whine, not a buzz. kind of like a pulley is slipping but rhere are no pulleys there. i already bipassed the SAS using the ECM sodering bipass on pin 37 and 35. did that awhile ago.

 

Sounds like the transmission pump. Not going to be a cheap fix if that's what it is.