1. Home
  2. Volvo automobiles
  3. bearing noise s70

bearing noise s70

Hello, I am hearing a knocking - tapping noise that sounds like it is coming from one of the accessory items. The AC compressor, alternator, PS pump, are my primary suspects. I have tried touching these items while the engine is running to see if I can narrow it down and I can not reach the AC compressor and can not distinguish between the others. These parts are so close to each other and are mechanically bolted to virtually the same place it is hard to tell where the sound is coming from by feel. The idler and tensioner are possible too, but the noise seems to be more forward than those parts. The car has about 130K miles on it and this is the first of any these parts to give any trouble. It is a 98 model year.

My question is what are the best ways to narrow down the problem ? I don't want to guess or use the shotgun method and replace them all, as all the parts seem pretty expensive and it is a tight place to work. To get to the alternator out, for instance, looks like the PS pump must be removed from the car to get to the alternator, hope there is an easier way if the alternator has to be replaced. I would guess the AC compressor might be possible to access from below?

Funny thing is that, for now, everything seems to be working fine. I don't want to let this go and have it strand me at the side of the road.

Thanks for all suggestions and help.

Reply to
My_roller2000
Loading thread data ...

I am dubious it is coming from any of those items, although the PS pump is a possibility. The A/C compressor is actually a very strong suspect except for something you didn't mention: does the tapping go away when the A/C is off? If so, you've found the source, otherwise, look farther. When disengaged the A/C compressor just presents a bearing to the rotation. The bearing could have a broken ball, but those usually result in intermittent jamming of the bearing. Just about the same with the alternator; knocking-tapping doesn't square well with the mechanics of it.

The P/S pump could certainly do it, but I'd be reluctant to shotgun it. Auto parts stores (and Sears) sell a "mechanic's stethoscope" that fits a metal rod to a stethoscope earset to help in finding noises like this. My experience is that metallic sounds seem to be everywhere, but at $20 US or so it might be your wisest approach at this point.

Mike

Reply to
Michael Pardee

Remove the accessory belt, start the car and see if the noise has gone away. If it has, manually spinning the accessories, idler and tensioner may indicate which one is bad.

Reply to
Mike F

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.