My mum went off to the grocery, after having the car sit in the garage all night, and it made a very odd whirring sound for approximately 30 seconds. I had her drive around the block, and the sound did not return. Tomorrow morning my father is leaving bright and early, and I will listen to see if the sound makes an appearance once again. I made sure that there was oil in the engine-completely full-and had a look at the drive belts, but there didn't appear to be anything amiss. I know that the information is vague, but this is all I have at this point. Thank you one and all

check out this link - http://volvospeed.com/Repair/airpump1.htm , it will show you how to remove and check the air pump. the typical problem is water in the pump, when i removed mine on 1998 V 70 it was clean and dry inside. I understand that the pump should make a high pitched whine at cold startup, for 1-2 min. i found several bad vacuume line elbows and replaced them. Mine still isnt working properly, i never hear it at startup, but when i shut it off after a short drive (10 min.) it may be running after shutoff, maybe a bad relay near radiator?

Your cold start air pump may have water in it. Normal fix is to drill 2 1/8 inch holes in the plastic to let it drain. You will need to disconnect the battery to get to it, so have the radio code on hand first.

Klaus
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(V♂LV♂s 1975 164, 1995 854T, 1998 V70R)

Air pump maybe?

It normally runs for a couple minutes at startup only. Is a bearing going in the pump? Has this sound only recently started?

The airpump is located under the battery behind drivers front headlight.

A DIY job if it needs replacement.

UPDATE: The sound disappeared for a few days, then this morning when the car was started it made the whirring noise again. The timing belt and tensioner were replaced in late September, so I am highly doubtful that the problem resides there. I am almost certain that it is an issue with the air pump, however intermittent. The one thing that has been a constant is that it only happens when the car has been sitting overnight, and the temperature drops into the 30's. The car does sleep in the garage, however :)

Could just as easily be a tensioner bearing in the timing belt or serpentine belt circuit taking a dump. I replace more of them for "whirring" noises in the morning. Next time it does it shut the car off real quick and remove the serpentine belt and the timing belt cover, restart the car and see if it still does it. If it is still doing it use a mechanics stethoscope to locate the bad bearing and be damn careful with the probe around all of the spinning stuff. If the noise goes away after you removed the serpentine belt then you will need to figure out which bearing it is in the serp system. It is usually the tensioner or the idler and rarely is it an accesory like the alt, p/s or a/c. To diagnose the faulty pulley/bearing in the serp system put the belt back on it and use the stethoscope to locate the offending part. Obviously when it makes the noise you need to have ruled out the air injection pump first.

Mark

SECOND UPDATE: I just performed another "hearing" test, and there was absolutely no sound. I am certain that there is no issue with the timing belt set-up, and if a problem does exist, it is with the air pump. I am wondering though why it only happens every four, or five, days,-twice in total- and why the check engine light isn't spitting out codes if it is indeed an issue with the air pump. I checked out IPD's website, and they sell a air pump kit($595) for the '96 850-so if it does indeed need replacing, IPD will be getting a ring from me :) Have a splendid weekend one and all!