buzzing like noise?!

Hi first time on the forum and first buyer of a Buick.

I just recently bought a 1971 Buick skylark 350 4 bbl with auto trans

it has added on tac and oil pressure and temp gauges


now my question the other day took it for a drive and i got it on the highway heading to work and i was nearing 3000 rpm and all the sudden i hear this weird buzzing type noise but when i let off the pedal below 3000.
RPM it stop making the noise i had a person tell me it was my belt for my fan im not to sure but other than usual oil leaking not to bad of a ride i also noticed the speedometer its way off so when im in the 3000 rpm range i get to about 55 or 60 mph i think it might be the speedometer but im not for certain

any ideas would help a ton thanks

 

Silly question but does your speedometer have the speed alert function (a knob at the bottom of it with an extra hand)?

 

Also consider the speedo cable.

 

Excellent point. Sometimes it really is the simplest of things that trip us up. If not, I'd pull the cable core out, clean it up good, wipe a thin coat of lithium greae on it and put it back in. I would also disconnect the other end and spray some brake clean in there and blow it out good with compressed air if you have it available.

 

ha, oh man the first time I figured out what that thing did.
I forgot I set it and finally got to that speed, scared the bejesus out of me. ou:

 

yea this moring i went to get me a drink at my local gas station asked my papa
he mention the whole speed thing ill check that when i get home and ill let you all know
how it worked and id put a pic up of the car but i dont know how to do it yet.


thanks' guys

 

I do not see one? On here

 

If your car has the Speedminder, it'll have a little black knob sticking out of the lower face of the speedo, and an extra indicator "hand" inside the speedo face that moves when you turn the knob. No knob, no Speedminder.

Did '71's have the seat belt warning system? If the buzzing is coming from the dash area, fasten the front seat belts and see if it stops.

 

The same buzzing noise can seem to come from the dash but is actually the voltage regulator mounted on the engine side of the firewall.
Showing up at lower RPM has me thinking this may be your issue.
Easily replaced with a solid state regulator available at any parts supplier.
Take the cover off & put the cover on from your original.

I've tried a modern wound coil regulator available but the buzzing remained. No adjustments on them like the originals.

 

Need to have ten post on the board to post a picture.

 

ill see if i can upload a video or somthing i cant really describe the noise

 

This is my guess.

 

If its not the speed alert I agree it could be the Voltage Regulator

 

Fixed it

it barley had any steering fulid in it

 

Considering this I suggest you carefully investigate the reason it became low on ps fluid.

 

Ok guys, took car out for a few days ago, and getting the same buzzing noise, and noticed that my voltage under load is way down. car running voltage gauge at 13-13.5 or so, lights on voltage down to 8 to 10. battery not being re-charge at all, constant jump starting. Took alternator to A/C shop andall good. Now i have chrome alternator from advance auto with internal votage regultor so instead a external one i have a voltage conversion harness from year one, any chance that can be bad ?

 

Very good chance that it is in the wiring.

With the wires being 41 plus years old, if not the wires then some of the connections could be what is bad.