The main vacuum line going from the UIM looked OK. No cracks, etc.

Below is a pic of the PCV housing. There are two o-rings in there...should there be more?


And, here'* proof of the oil fill cap o-rings!


Bugsi--how did you positively identify the alternator making the whistling? I have a spare alternator...maybe I'll bolt it on and see if it still does it.

Those o-rings all look like they're in the right places, vital. Check all your vacuum fittings and lines carefully. How old is your actual PCV valve? I don't know if it would help, but maybe you can throw another one in there.

I cheated. I had the car at the dealership for some other problem (brakes) and also told them I had some sort of weird whistling that raises in pitch with engine speed, and that I have it even when the car is in Park. They called me back after they checked it all out and told me it was the alternator, and suggested not replacing it unless I was *REALLY* annoyed by it. As it turns out, I'm not that annoyed by it, so I took their advice and didn't get it replaced.

As for how they diagnosed it, I have no clue. I just trusted that they diagnosed it correctly. I guess technically I'm still just trusting that their diagnosis was correct.

Unplug the connector to the alternator, not the big wire but the plug with 2 or 3 small wires. If noise is gone, it'* the alternator. You can also remove the drive belt and see if the noise goes away, but don't run the engine too long without a belt or you'll overheat it.

The cap I referred to was the PCV cap, not oil filler.

Alternator bearing are going bad?

In relation to whistling or whining noises, i'm always annoyed by the whine of alot of foriegn cars with the 4 bangers. Mazda'* are worst for it i think. I remember a Protege I had made a whine, which I sorta found annoying.

I don't have it anymore. I have something else better!!

:? Not sure why unplugging an electrical connector would stop a mechanical whistle.

But, I will bolt on the spare alternator I have and see if the whistle still exists.

Unplugging the connector would remove the load the car is asking for... however.. a bad bearing would and could still exist.

I worked on this issue last night...

I first replaced the PCV with a brand new one. Whistling was still present.

Then, I went on to the alternator. As suggested, I unplugged the 4 prong wiring harness off the bottom of the alternator. Went for a drive...still whistling. :?

My last resort was to replace the alternator with my spare. When I removed the old one from the car it spun freely, but I still had my doubts so I continued with installing the "new" one. Got it installed, went for a drive and STILL whistling.

I wasn't sure what to do at this point. So, I left the engine running and put a dowel stick as close to each pulley as possible and listened to the other end of the dowel stick for a whistle-type noise. I got nothing out of any of the pulleys other than the normal buzzing sounds from the bearings moving.

The only thing I can figure is that this is a vacuum related leak or my gatorback belt.

:?

Oh, you have a gatorback belt? They are known to make a whistle type noise. Do you have a regular belt you could toss on to check?