Re: bearing noise s70
Michael Pardee wrote:
> "My_roller2000" <My_roller2000@yahoo.com> wrote in message
>>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.
> 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.
The noise is present with the ac off, I actally did not try listening
with the ac on as I figured the bearing was in motion even with it off
as the belt is turning the pully on the ac, I realize the ac clutch is
not engaged so other ac internal parts are not turning.
I will look into the "mechanic's stethoscope" and see if that helps.
thanks for the suggestion and quick reply too.
I look forward to other suggestions also.