Engine Making Whining Noise, Alternator Maybe?

[Unner]

Hey everyone. Yesterday I noticed my engine is starting to make a whining noise almost like a supercharger, but I don't have one... The noise increases with RPM, and seems most noticeable around 1500-2000 rpms. After that it gets kinda drowned out with the regular engine noise.

At first I thought it was the power steering so I siphoned some of it out a few times and cleaned the filter in the process. I got a little dirt off of it, but it wasn't bad and the noise is still there.

The noise isn't in the drivetrain as it still makes the noise while sitting in park.

I think it may be the alternator because after running it for just a few minutes from a dead cold start the silver case on the alternator was too hot to touch. Everything else was still cool enough to touch, the scangauge said the coolant temp when I shut it off was 114*F.

I let it warm all the way up and all the pulleys are still cool to the touch, including the alternator pulley, but the alternator case itself was very hot at this point. I think the two things it could be are the alternator or the lower tensioner pulley, but that pulley was cool to the touch so I wouldn't think it would be that. It also kinda sounds like it is coming from the alternator area, but it is hard to tell.

The truck is just a few miles shy of 170k right now and the alternator appears to be the original. I'm leaning towards it being that.

Here's a video showing the noise.

Any suggestions or help is greatly appreciated. I'd like to get my truck back to full strength as quick as possible.

 

[Unner]

Actually the pulley on the alternator is warmer than the other pulleys, especially when I put my finger inside kinda where the bolt that mounts it is. The other pulleys weren't warm at all but that one was even after cooling for 30-45 minutes. I would think that means that the bearings in it are bad causing it to heat up and also make the noise?

I assume a new alternator is in my future?

 

[Squirt]

I would most definitely start with your alternator... go get it tested before you pull the trigger on a new one though. AUTOZONE or CARQUEST will test it for you for free.

 

[jhfleet]

Actually the pulley on the alternator is warmer than the other pulleys, especially when I put my finger inside kinda where the bolt that mounts it is. The other pulleys weren't warm at all but that one was even after cooling for 30-45 minutes. I would think that means that the bearings in it are bad causing it to heat up and also make the noise?

I assume a new alternator is in my future?

If you have a few tools, remove the belt from the alternator and start the engine.

 

[Unner]

I just bought a new alternator at advanced auto. I'm gonna do what jhfleet said and pull the belt and see if the noise stops, and if it does then I'll put that new alternator on and hopefully the noise will stay away. If the noise continues I'll return the alternator and look elsewhere. The only other part that had similar symptoms was the AC idler pulley, but when I used a large screwdriver as a stethoscope that pulley seemed to be turning smoothly and not making noise, and the same goes for the power steering pump. I pulled my Supra out which has the same style alternator and is easy to access and it sounded much smoother and quieter than the 4Runner one so I'm nearly certain it is the alternator at this point. The noise seemed to be coming directly from the alternator when using the large screwdriver as a stethoscope.

 

[Alabamaguy]

Check the alternator, have it tested, put a multimeter on the battery and see what the voltage is at idle. I had a similar noise and it was the transmission/tq converter bearing. Just thoughts. Try not to throw money at it when you can test for free.

 

[Rock_Rat]

Timing belt and water pump?

When did you change your belt and pump last? Is your scan gauge showning 13+ volts? if you have a long stick you can place it on the parts and listen for any noise. Just be careful with the engine running. Works like a stethoscope. Take your time troubleshooting for sure and hope you isolate the problem.

 

[Unner]

Thanks for the help everyone. It was the alternator as suspected. The scangauge was not showing anything close to 13 volts, more like 11.5-12.3 at idle... I did what Rock_Rat mentioned with a long screwdriver and prybar I had and that made it pretty clear that the noise was coming from the alternator. I got it swapped and all is good now. I hope this one lasts a while. I couldn't get a Denso locally so I went with a generic Advanced auto one that was half the price of the Denso. I had them test it at Advance when I picked it up and he said sure enough, that the alternator is on it's way out.

And just to answer the question, my last timing belt change was 86k miles ago so I plan to have it changed here in the coming months once I am a little closer to the 90k interval.