Whirring sound from new tensioner?

[nyan]

Hey all, just want to see if anyone has had any experience with this. 1996 Z3 1.9 M44 engine.

A few weeks ago I replaced the belt tensioner and idler pulley on my M44 engine because old tensioner was squeaking. I put in a new one from Continental. After the new one was put in the squeak went away but I started noticing a faint whirring sound from the engine bay. It's RPM dependent and present in all gears and also in neutral. Most noticeable driving in the neighborhood in 1st, 2nd, after getting to 3rd the loudness of road noise kinda takes over volume-wise.

I figured whatever the source of the whirring might be I never heard before since the tensioner squeaking was masking it. I used a screwdriver pressed against different components and there was a whirr coming from the alternator, so I figured maybe the bearings were going out. I rebuilt the alternator with new bearings and new brushes, which was timely because it turns out one of the brushes was on its last legs. But the whirring is still present.

While the alternator was out I also dismounted the PS pump to clean it up and address the seeping hose issue. The PS pump was reinstalled and rez was filled with new fluid (Dex III) and bled. I should also note that I did a cooling system overhaul last year so the water pump is only a year old so I don't think that's the issue either.

At this point by process of elimination I'm figuring the thing that kicked off me noticing a whirring is the new belt tensioner. Being a bit short on foresight I threw the old one away after removal so I can't pop the old one in to confirm

Has anyone experienced this symptom before? Tips and tricks to diagnose? I'd rather not have to buy a new tensioner to test this hypothesis. Save me some $$$ Thanks

[Vintage42]

... replaced the belt tensioner and idler pulley on my M44 engine because old tensioner was squeaking. I put in a new one from Continental. After the new one was put in the squeak went away but I started noticing a faint whirring sound from the engine bay...

Continental -- is that the tensioner or pulley or both? Is that the brand or the vendor? If the tensioner, did you tension it right, and have you tried re-tensioning it? If your are sure it's the tensioner, get a more expensive OEM part.

[nyan]

The Continental tensioner came with a pulley as an assembly. Continental part number 49310. BMW P/N 11281432104 per RealOEM. I got it from RockAuto. I think INA might have made the original that came on the car. Is the tension adjustable on these things?

I'm convinced it's not the tensioner. I had the car running just now and applied pressure clockwise and ccw on the tensioner via the torx head and the whirring sound didn't change. It's something connected to the drive belt though because if I take the belt off the whirring goes away. I'm going to get a stethoscope tomorrow and dig deeper. If I can't find anything I'm just going to leave it alone. The whirring is very faint.

Continental -- is that the tensioner or pulley or both? Is that the brand or the vendor? If the tensioner, did you tension it right, and have you tried re-tensioning it? If your are sure it's the tensioner, get a more expensive OEM part.

[lyunardo]

How did this turn out for you?
Did you find the source of the noise?
I'm getting ready to replace the tensioners too, and want to avoid this.
thanks

The Continental tensioner came with a pulley as an assembly. Continental part number 49310. BMW P/N 11281432104 per RealOEM. I got it from RockAuto. I think INA might have made the original that came on the car. Is the tension adjustable on these things?

I'm convinced it's not the tensioner. I had the car running just now and applied pressure clockwise and ccw on the tensioner via the torx head and the whirring sound didn't change. It's something connected to the drive belt though because if I take the belt off the whirring goes away. I'm going to get a stethoscope tomorrow and dig deeper. If I can't find anything I'm just going to leave it alone. The whirring is very faint.