Whining sound coming from engine bay of my 2009 SR5 V6

Tonight, a whining sound started in my engine bay (1GR-FE). It's present at idle in neutral and while underway. It's proportional to RPMs, and definitely sounds like it's a higher frequency than crankshaft RPM.

It *almost* sounds like the transfer case does when it's in low range. Needless to say, I'm 2WD high.

I popped the hood. Two days ago I had the truck state inspected and serviced, which included an oil and filter change. It appears that when they changed the filter, some oil got on the alternator. Could this be causing the whining? Now to be fair, I'm not 100% sure that the oil on the alternator is new.

There are 125,000 miles on the truck.

Thanks for any replies.

 

Maybe a pulley is on the way out.

 

You could remove the serpentine belt and start the truck.
If the noise goes away, it’s a belt driven accessory.

 

This morning there was no noise. The truck was in the garage last night and was relatively warm.

Last night when I had the noise, the truck had been cold-soaked for a few hours.

Would a needle bearing noise be starting-temperature-dependent?

Thanks.

 

Alternator.

 

If it is the alternator or an idler pulley, how long until I'm left stranded? How high a priority should this be?

Thanks again.

 

I'd just spend the $100 on a rebuilt alternator if you're worried about it going out. Getting a tow truck around the holidays sucks.

 

Hasn't done it today at all, even after being out in the cold.

Strange.

 

Power steering pump?

 

There’s no good answer.
The best answer is, are you a risk taker.

I’d also recommend not throwing parts at it. Crawl under there take the belt loose.
You don’t even have to take it all the way off. Spin the idlers and pulleys. You will know when you hear and feel the one that’s bad.

 

Sounds like the noise is intermittent.. if/when it comes back try taking the belt off like Tn suggested. That will isolate it to something in the belt drive system.

If you suspect the alternator is whining, try removing the field connector with the engine running and see if the whine stops. That would indicate a failing alternator.

A mechanics stethoscope is pretty cheap and can help with noises

 

This. I would bet its an idler pulley myself.

Loosen the belt and give yourself enough room to free wheel each idler. You'll be able to feel and/or hear a bad one. Mine were noisy only under cold start conditions as you mention, once warm warm they quieted down for the most part.

 

The dealer worked on the truck this week (did front brakes and rotors and some other stuff). They also spent two hours trying to reproduce the noise (that's always present). They could not. They said they think all my idlers are OK.

The noise almost sounds like a small turbine wind-up.

WTF could it be?

 

Have you tried any of these suggestions yet?

 

The dealer tech did all that. I spoke to the service writer several times on the phone during the diagnostic work. I trust that they were thorough.

 

Almost 14 year old truck with 125,000 miles. I'd replace the pullys since they're relatively cheap (and the serpentine belt if you haven't already). Why risk it....

 

What does a set of pulleys cost?

Thanks.

 

Around $50, give or take, for a set. if you want toyota OEM brand about $150 for the set. But honestly for a truck that old, an aftermarket set is fine.

And they're easy to replace with basic tools. Took me about an hour to do a few years ago.

 

Thanks for the info.

How exactly would I remove all tension from the belt to test if the pulleys are bad? Is there a way to do that? How long can I safely run the engine with no water pump and no alternator?

Thanks.

 

https://www.fjcruiserforums.com/threads/idler-pulley-bearing-failure-what-to-do.127154/

Your thermostat will still work so if you see it getting hot then shut it off. You won't have to run it long to confirm the fix.