Strange whine/moaning sound from engine

cbpitt01 · Post by **cbpitt01** » 12 Feb 2018, 22:51

2006 V70 2.5t, 209000 miles. About 1 week ago, the sound started. Car drives fine, engine temp fine, mpg normal, alternator and battery check out fine, no codes thrown. The noise is definitely coming from the belt side of the engine. I’ve a feeling it’s not electrical. Sound is not present when cranking the car from cold, but starts after car has run for 5 minutes or so - or immediately if car is cranked while still warm. Sound is most evident at idle and low RPMs, but not noticeable once engine speed rises. In the beginning, it did sound like an electrical hum, but now it’s coarser and not as steady - it rises and falls somewhat at idle speed. I read somewhere this had happened to someone before, and it needed up being failing hearings in the accessory belt tensioner pulley. Just trying to get ideas before I go into the dealership. Any guesses are appreciated! (I tried to post a 5-second video clip, but it tells me the file is too large).

Post by **RickHaleParker** » 12 Feb 2018, 22:57

Get a stethoscope and play doctor with your Volvo ... pinpoint where it is complaining.

Post by **oragex** » 12 Feb 2018, 23:04

Going to the dealership should be the last option.

I'd check the power steering pump fluid level and color (green), or a clogged PCV (test on Youtube)

cbpitt01 · Post by **cbpitt01** » 12 Feb 2018, 23:15

I forgot to mention that I checked the power steering fluid level - level and color are fine, plus the sound doesn’t change tones when I turn the wheel. PCV service was done about 6000 miles ago, and there’s no suction at the dipstick tube nor the filler cap.

cbpitt01 · Post by **cbpitt01** » 12 Feb 2018, 23:21

RickHaleParker, I think I’ll try that. Harbor Freight has an el-cheapo one for $3.99 - before the 20% off coupon even! Don’t know how good it’ll be, but better than nothing.

cbpitt01 · Post by **cbpitt01** » 12 Feb 2018, 23:32

Posted it on YouTube so I could copy it to here. This is the sound when it started about a week ago...

cbpitt01 · Post by **cbpitt01** » 12 Feb 2018, 23:33

And this is how it sounds today...

Post by **RickHaleParker** » 13 Feb 2018, 00:12

Hum ... watch, listen and compare.

Post by **abscate** » 13 Feb 2018, 04:17

A stethoscope or a piece of hose will isolate that noise. You want the end right near the appliance in question..I got fooled by an AC compressor that was noisy through the alternator and replaced both.

cbpitt01 · Post by **cbpitt01** » 08 Mar 2018, 15:16

Sorry I disappeared for a while. I got a cheap mechanic’s stethoscope the next day, but then was ill for a week and didn’t drive the car much and didn’t try to pinpoint where the noise was coming from. Scheduled an oil change at the dealer (I take my own Mobil 1 and a filter - my old neighbor gave me 15 free filters when he sold his Volvo - and they do it for $19 labor), and when I cranked it to drive it in, the sound was gone. I told the dealer about it, showed them the videos, they checked and listened, and said nothing was out of the ordinary. Said both accessory and timing belts looked great, pulleys were quiet, all fluids (power steering, brake, coolant, auto trans) were at correct levels and all were correct color and none had burned or otherwise odd smell. Only additional thing car needed was an alignment, and I didn’t doubt that, as I had hit a huge pothole a few weeks before that wasn’t there one day and was the next due to heavy rains. And car didn’t show any codes to them when they scanned. So who knows what it was? But I’m glad it cured itself. Thanks, guys, for the suggestions.