Engine noise?

This morning I noticed a new engine noise when I started up. I couldn't tell at first what the noise was, just that something was louder. When I turn the engine off, the last sound is about 1 second of a pink noise type sound that I haven't heard before. It's like the sound of a worn bushing rotating to a stop. It's hard to hear from the cab except for that feeling that there's more noise in general while it's running, whether at idle or moving. To really hear it I have to be either in the cab turning off the key inside my garage where the noise echoes good, or standing by the engine bay while somebody else does it. I had a friend help and it sounds like it's inside the engine, straight in the middle. Not the serpentine belts, not the fan. Hoses look fine. Everything in front of and on top of the engine looks fine. No leaks. No CEL. Fluids all good.

As noises go, it doesn't sound terrible, in my opinion. No noticeable performance difference.

 

It's not the A/C?

 

The AC is off when I shut off - Would that matter? It's possible it started yesterday when I did use the AC briefly and I didn't notice the noise.
Is there something in particular about the AC system that would start making noise? I am not familiar with where it is, other than the belts diagram shows a cooler compressor pulley kind of on the left bottom.

 

Hark ye!
Thou approaches with false pretense.
There be another expression instilled,
Its clamor not immense.
Lest ye look with thine mind,
Thou can never find,
The sound which boggles so,
In phase change it resides.

 

Would some kind of AC service fix this? Could it be anything but the AC? I don't have it on. The noise increases as I hit the gas more, drowning out the stereo when I accelerate from every stop. It was not like this before a few days ago.

 

Check your idler pulley, below the AC condenser.

 

The noise isn't coming from the three drive belts or their pulleys. It's further back, something not visible I think.

 

Are you using a stethoscope to track down this noise? If not I'd highly encourage you go pick one up [they're only like $10 at O'Reilly's]. These noises can sound like they're coming from a totally different source, and the stethoscope is the best way to track down the true source/location. I had a bat idler pulley, that I was literally positive was coming from the upper engine area [near the throttle body], and it sounded like a vacuum leak to me. Stethoscope helped prove I was wrong

 

x2 on the auto stethoscope- they are a game changer.

I'd also just throw out there, to check the power steering fluid.

 

I'll work on using my stethoscope soon. I don't suppose there's an easy and safe way to kill the engine from the engine bay?

 

Not other than to yell at someone else sitting in the driver's seat to turn it off. They're may actually be a way, but I'm not aware of one

 

Here's what I found with the stethoscope. When testing with a friend I couldn't get the lingering 1 second of friction noise to pin it down when shutting off the engine, so that appears to be intermittent. So this is just testing at idle.

- AC belt tested from center bolt sounds very quiet! (yeah the belt is on, ha)
- Alternator and PS pulleys have a center bolt that spins with them, but the metal and bolts nearby have a significant but low pitched rumbling sound.
- Fan/water pump pulley tested from the bolts nearby has a higher pitched sound. Maybe a little suspicious.
- Idler pulley, which the AC belt goes over, tested from the center bolt has a higher pitched sound like the water pump, but even louder.

What do you make of this? The idler pulley is making the worst noise in my estimation, as @Red_03Taco suggested. How did you guess? Is it common for that to go out first? The others I'm not sure what to make of.

All pulleys I believe are original. Alternator belt and AC belt have 40k on them. PS belt I replaced to successfully fix belt squeak a few months ago. I tightened the PS belt and alternator belt during that job to spec. I did not have to tighten the AC belt, according to my notes.

I stethoscoped various other parts of the engine bay just in case but didn't find anything of note.

 

I'd suggest removing your idler pulley (with the engine off of course), and spin the pulley by hand, and listen to see if it spins smoothly. You'll feel a roughness in how it spins in your hand if its shot.

To answer how I guessed it: I had my idler pulley go out a few months back, and it sounded like all sorts of other things before I tracked down what it was. Doesn't help that I'm deaf in one ear, so tracking down noises without the stethoscope is near impossible for me. When you originally described the noise (as nothing real distinct, just generally louder engine noise all the time) that reminded me of what mine sounded like. Also, yes the idler pulley commonly goes out, and does so more frequently than most of the other drive belt components. I suspect because its lower down on the engine, it sucks up more dust into the bearings over time, which implies to me that the stock Toyota dust shield that sits in front of the bearing is important, so make sure to put that back on once you replace your pulley.

AutoZone carries a pretty decent idler pulley for our trucks (Duralast brand, model #: 231038) for about $30. It uses the same type of bearing as the stock Toyota one, and the stock dust shield fits in front of it. Or you can keep your Toyota one (I hear the Toyota one is of higher quality), and can press out the center bearing and replace it with a

$17 6301-2RS Bearing - Lubricated Chrome Steel Sealed Ball Bearing - 12x37x12mm Bearings with Rubber Seal & High RPM Support

6301-2RS bearing (very cheap to buy the bearings on Amazon). Pictures of both options included below for your reference.

 

Or you can buy just the bearing for around $8 at a motorcycle or bearing shop and replace the worn one in the pulley.

 

I got the Duralast idler pulley, which spun with my hand smoothly and quietly. My old pulley I pulled off is indeed noisy and has a wobble.

I installed it, and on startup it's making a bad screeching sound. I shut it off immediately. Am I supposed to grease anything on the fittings?

I thought I replaced it like it was. I cleaned the parts before reinstall. First I put on the small stepped washer. Then I put on the pulley, with the indented side facing in so that the washer slips into it. Then I put on the larger fitting, and the nut. I tightened the tensioner bolt to the same belt tension I had before, then tightened the pulley nut.

 

Here a pics of the parts in the order I installed them. I didn't lose any parts. The belt is in the grooves on all pulleys. I even wiped down the area of gunk before reinstalling. The pulley spins good on my desktop and when installed before I put the belt on. What could be causing this noise?

Maybe I got a little gunk on the belt when pulling the old pulley off? I wouldn't think it would cause this kind of noise.

EDIT: Nevermind, see below.

 

OK I'M A DORK.

I left my shop light deep in the engine bay and it was rubbing against the alternator pulley to cause the noise. No damage as far as I can see.

New idler pulley is good. No test drive yet but it sounds good. However when I had the belt loose I noticed the AC pulley has a wobble. Oddly enough, that was the one that sounded the most quiet per my stethoscope test. Is it easy to replace, or to put a new bearing in it?

 

I've never had to do my AC, PS, or alternator pulleys, so I can't weigh in on how difficult it might be. I'm sure someone else will reply to this thread and answer that question. Glad you figured out the screeching noise lol

 

Turns out the original noise is unchanged. Alternator pulley bearing is fine. So it's either the AC pulley which is known bad, or PS pulley which is a pain to even check, or something else entirely.

There are some other threads on the AC pulley/clutch. It's more work but might be doable.