I have a 70 cutlass 350 that has a slight but annoying whistle at idle. When I remove the alternator belt the noise disappears. So I replaced the alternator and belt( fusick ). Whistle still there. Next I replaced the water pump. Nothing. Next the crankshaft pully. Still nothing. Also replaced the voltage regulator, positive batterycable, battery and stranded engine ground which was missing. Seems to get louder when I turn on the headlights. Goes away when in drive with foot on the brake. Any thoughts?

 

Possibly a vacuum leak

 

If the noise is definitely alternator related, it's likely the front bearing in the alternator going bad.

 

Thanks. Just wondering if I need to drive it for a while and let the battery fully charge and let the alternator break in. I’m baffled because Fuscik always has quality stuff and since it’s the same noise as the previous alternator. Frustrating!

 

QUESTION: Can you duplicate the exact same condition as your previous ALT? IOW, when you remove the belt from this new ALT, does the whistling noise disappear?

It's tough determining what a "whistling" sounds like. Everyone may have a different opinion - a squeal, a high-pitched whistle, low-pitched, etc. - constant whistle or intermittent? I'm posting the following ONLY to help understand what the whistle sounds like (regardless of any viewer comments on the video). Does it sound like this video? Constant, intermittent? High-pitch, low-pitch?

 

We used to use a load tester on cars to see if it was charging. When load was applied you could hear the alternator whine.... is battery fully charged?

 

Change your bearings.

 

Whine is nothing as bad as the video. Just let it idle for about 20 minutes. Whine eventually mostly stopped and greatly reduced when I turned on the headlights. I’m guessing the new battery has to fully charge and maybe the new alternator break in. Hoping. Thanks again for responding .

 

You'd change the bearings on a brand new ALT you just purchased from Fusick? Not sure how that works.

 

I suspect the whistling will stop after you drive it several times. If it were bearings I suspect it would be loud and continually very noticeable. I've replaced a newly rebuilt ALT & upon start up for several days it whined for 5-6 minutes (at startup). Noise stopped under load i.e. in DRIVE with foot on brake and couldn't hear a thing while driving. It did this for 5-6 days and finally the noise was completely gone. Take it for some drives for a week or so. I'm hedging under various loads of normal driving the noise will be gone. Ensure you have the ALT belt tightened correctly. You should have ~1/2" movement - you can tighten them pretty snug.

 

No. Not at all. I would just send it back. But since it’s producing the same whistle as my previous alternator it’s probably not the issue.

 

Of course you would. My comment was not directed to you, BTW.

 

Thank you Vintage Chief. I think that’s it.