Alternator Humming?

[1owner1990]

Hey all,

I've entered the 'systems check' stage of a nut & bolt restoration and upon keying the ignition switch to the 'run' position, a faint 'humming' can be heard from the alternator. The hum can really only be heard from a fairly close proximity and IS NOT accompanied by warm wires, odd smells or warmth on the alternator itself and it goes away when keyed 'off'. The alternator is a reman Delco (see photo). Googling 'humming GM alternator' got me nowhere, as half the posts say the vehicle is about to burst into flames, while the others say it's perfectly normal (some even point to reman Delcos being particularly notorious for humming for some reason?). Not clear which vehicles all the posts were referring to, and I really need a sanity check at this point. I'm hoping someone here would run out to the garage, key-on their 400 and put an ear about a foot from the alternator to see if there's a hum. In all the years I've owned this truck, I've never noticed a hum (nor have I had a reason to have the key on with the hood open). I look forward to your input, thank you for any help here.

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[Erik the Awful]

Key on, engine off? There's a thread on the HAMB about this. https://www.jalopyjournal.com/forum...s-great-but-hums-when-ignition-is-off.853425/

 

[eran tomer]

is it a cs144?

 

[454cid]

is it a cs144?

That looks like a CS130, to me.

 

[eran tomer]

That looks like a CS130, to me.

according to the parts diagram the brace that connects to the exhaust manifold doesn't exists on cs130.

 

[454cid]

according to the parts diagram the brace that connects to the exhaust manifold doesn't exists on cs130.

You've got a newer truck. Are you thinking of the CS130d?

 

[clgodwin79]

I also Googled this but used the word buzz instead of hum and found several people who have had the same issue and it didn’t affect the operation or function of the alternator at all. Definitely very strange though.

 

[1owner1990]

according to the parts diagram the brace that connects to the exhaust manifold doesn't exists on cs130.

I knew y'all would ask for specifics. I don't know cs130 from cs144. The part # is in the pic. The bracket is irrelevant. It's a GM crate motor, not original.

 

[1owner1990]

Key on, engine off? There's a thread on the HAMB about this. https://www.jalopyjournal.com/forum...s-great-but-hums-when-ignition-is-off.853425/

Thanks buddy, that's one of the posts I found. Makes me feel like its ok.

 

[1owner1990]

I also Googled this but used the word buzz instead of hum and found several people who have had the same issue and it didn’t affect the operation or function of the alternator at all. Definitely very strange though.

Thank you.. hearing others with the same question makes me feel a little better.