3.0L M54 engine whirring noise

[Effduration]

Congrats on the big project.

Take some of the cash you saved doing it yourself and buy a mechanics stethoscope for <$20 on amazon. Its a very handy tool.

You will narrow down that sound pronto.

[rmr2122]

I just ordered one!

[andrewwynn]

That sound could be a DISA valve. I think you can unplug to confirm.

[80stech]

As Wpoll points out, the bearings are possibly going to be a problem down the road after pressure washing. Alternator bearings are high speed and non-contact seals so NOT water proof.

[andrewwynn]

On second listen I'm only hearing valve train noise. Let us know if you locate a distinct source.

[oldskewel]

Originally Posted by rmr2122

I did power wash the engine pretty aggressively during the maintenance! The alternator was completely coated in oil and grime so I couldn’t resist cleaning it up. I wonder if I could’ve misaligned during power washing or even removing/reinstalling for the oil filter housing gasket.

I power wash my alternators every chance I get. ( but not completely kidding) I definitely wash oil off them when I can. And yes, I've been reading what the intertubes say about this for decades now . I try to do it when the engine is warm so any residual water dries off quickly. Any sensitive electrical components are generally well sealed, and anything that is not sealed is generally very durable and resistant to water. Yes, I'll agree that if everything is kept perfectly dry, that should be OK too.

I rebuilt my Valeo 120A alternator when the slip rings wore out, also replacing the bearings since they had to come out anyway. Here they are, NTN 6303LU front bearing and NSK 6202DU rear bearing. Both have contact seals, and both were working just fine when removed at around 170k miles. These cars alternatively came with Bosch alternators - I don't know details on those.



From my experiences with my own old cars, I believe the thing that kills alternators other than normal wear and tear, is when they get wet with oil (or PSF, etc.). They are designed so the soft carbon brushes eventually wear away, hopefully after 150-200k+ miles. The powder debris from the wear escapes from the brush assembly through carefully designed ports. It has to go somewhere.

When oil (that won't evaporate, as water will) gets in there, the powder debris does not dissipate as it should, it collects and forms an abrasive paste that is always there, and accelerates wear on the slip rings, leading to alternator failure. Slip ring replacement is at least 10x tougher than any other alternator repair, so failure of that component usually means the alternator is dead.


Also - don't read all this talk about alternators to mean I think you have a bad alternator based on your video. You might. Tough to tell. It definitely does not sound right. Well done on getting all that work done. I'd spend some time with the diagnosis. Good luck.

[rmr2122]

Thanks oldskewel for all that helpful info. I just took a long screwdriver out to my car and can confirm that the high pitched whirring noise is definitely coming from the alternator. I'm leaning towards replacing with an OEM Valeo 140A alternator (which is what's in the car now) from FCP. The noise doesn't really bother me, but I need to drive my car from NY to Chicago and back over the next few weeks. Should I look to do the replacement before I leave for the trip? Or...I could get the new alternator and throw it in the back of the X just in case I run into trouble along the way.

[rmr2122]

I just remembered that when I went to reinstall my alternator after removing it to replace my oil filter housing gasket that I was having a hard time getting the alternator bracket to seat into the correct position on the OFH. So I tapped the top of the alternator very lightly with a mallet which seated it immediately. After reading the responses to this thread I'm guessing that hitting it with a hammer was the wrong move!

SO I power washed and hit my alternator with a hammer. Oops! I guess this is a live, learn, and order a new alternator moment.

[Bdc101]

When I replaced my alternator about 1.5 years ago (3.0), it was an absolute nightmare of a job to get the alternator bushing seated in the correct position to put the screw back through it. It took me twice as much time to perform that one operation than to do the entire rest of the job. What a nightmare.

[rmr2122]

How did you end up getting it seated?