Thread: High pitched whine from engine bay.

Sounds like the Alternator to me. Especially since it gets louder as the engine revs. Take the belt off and spin the pulley to see if it spins freely or if it feels rough. You can also start the engine with the pulley off to see if the sound is gone.

I'll give that a shot this afternoon, possibly the alternator going out?

Removing the accessory drive belt, then start the engine and listen for the noise. While the belt is off check all the accessories
for free movement, could be a bad bearing somewhere. Don't run the engine for too long without the belt.

Just check all of the accessory drive pulleys for freedom of movement? How long is acceptable to run it without the belt?

When you say back left, do you mean driver side or passenger side? It could be the abs module going out

You may be on to something here depending on where the ABS module is. It's the passenger side back near the alternator. I have been noticing my ABS activating at weird times, like turning hard left out of a parking lot, going down over the little ramp to the road and I can hear the sound of the ABS going.

the abs module is on the driver side, but if you have a wheel bearing going out, it could be giving bad signals to the abs module, and the abs could be pulsating the brakes at strange times. abs module is right in front of the brake booster.

Gotcha, I don't think I have any wheel bearing issues at the moment ha. I was tracking down a warbling sound from the tires so no more than a month ago I had all the wheels off checking the hubs only to find out one of my tires is dry rotting and has a major flat spot. So the ABS thing is still odd, albeit infrequent, but that's a whole other ball game for a different day haha

the wheel speed sensor in the wheel bearing could be the only bad part on the bearing, or it could be a wire issue, both situations are entirely possible.

Hmm I might have to check that sometime soon then. It's been pretty infrequent but unnerving when it happens because, well... you know, it's the brakes. Assuming it's just the wheel speed sensor which iirc is built into the hub, there's no easy way of narrowing down which is culprit without swapping and testing correct?

sometimes you can see the wires are F***** up, if you have an abs scanner, you take the car for a drive and watch the left and right wheels, if one doesn't match the other, then it is a problem.

the brakes will still work, I wouldn't sweat it too much.

I'll have to dig in there and check the wiring on them at some point. I don't have an ABS Scanner unfortunately, just a bluetooth OBD2 reader which I'm fairly certain doesn't read the ABS stuff sadly.

My Alternator was charging fine when there was a noise coming from it. Long story short, bearings were worn out and I replaced it with a used one from local pick and pull $20.00. Problem solved.

Oh yeah, I will definitely have to check my local pick and pull considering new ones are in the neighborhood of $130-$200.

My alt does the same thing. The old one did too and it finally quit charging one day. I slapped on a spare I had and it still does it. Sounds like junk and the pitch is ear piercing. Love to figure out if this alt is going bad too.

Originally Posted by FordMan77

My alt does the same thing. The old one did too and it finally quit charging one day. I slapped on a spare I had and it still does it. Sounds like junk and the pitch is ear piercing. Love to figure out if this alt is going bad too.

Think you answered your question. If it's making noise, something inside is going bad. It will keep charging if it's just the bearings, but eventually it's going to fail completely.

I just found it strange that the spare that I swapped on made the exact same noise right off the bat. Guess I'll add a new alt. to the list of stuff to get.