It sounds to me like the source of noise is outside the timing chain cover like some other bearing that's driven by the accessory belt. Did you check all of them or just the tensioner? Maybe try to localize the sound better. Did you replace the whole tensioner or just the bearing?

 

I replaced only the bearing. I really thought the tensioner bearing was the issue because it was definitely loud and rough before and now it is quiet and smooth, but it must be a coincidence because the issue still occurs. With the belt off, none of the bearings seemed to make any noise or have much play, but maybe it wouldn't be noticeable when turning by hand?

I'll try the screwdriver milk jug trick and see if I can localize it more.

 

Does not sound like a timing chain to me as it is too loud.

Check the radiator cooling fans, these have been known to fail in your model.

The other thought I had is that there are two idler pulleys for the accessory belt,, did you change the bearings in both of these?

Seagrass

 

I only changed the one on the tensioner because the other one is dead silent and smooth.

 

I'm also wondering if your tensioner was leaking and if a weak tensioner can cause this kind of noise. I'm not a mechanic just a regular guy.

 

So I just ran the car without the accessory belt and it did not make the noise, however the RPMs were also higher than they normally are because it had no load. I spun everything by hand and it all seemed totally fine. I tried the screwdriver + funnel trick and it seems to be pretty equally loud between the power steering pump and the alternator, but quieter on the engine and the AC compressor. Given that I've already replaced the power steering pump, could it be the alternator? I'm thinking that at lower RPM the alternator has to work harder and maybe something is making that noise?

 

I don't know - that rattle sound you had doesn't seem to me like what I would expect bearing noise to sound like but it does sound like something in open air, not something that's bathed in oil inside a timing chain cover. There's a slight chance that it's something else rattling, making contact with something else, only at a certain RPM under load causing it to move or vibrate just-so, like a hard line. Heck it could even be a heat shield or something?

 

Okay, I'm about 90% sure I've figured it out. I noticed when taking the belt off again that the tensioner is quite hard to push down, and makes a creaking sound when it does. I drove the car to warm it up, and with the air breather off of the car I can see the body of the tensioner vibrating when the noise is happening. As soon as the noise stops, the tensioner is no longer vibrating. Noise starts again, and the body of the tensioner is shaking back and forth again. I put the screwdriver + funnel contraption on the body of the tensioner, and the noise is way louder than when it's on any of the accessories. The tensioner also sits inbetween the alternator and the power steering pump, which is why they both sounded pretty equally loud. I'm going to replace the belt + tensioner tomorrow or this weekend and will update to confirm if that was the fix.

I think the bearing was bad, but since it was driven with a bad bearing for so long it damaged the actual tensioner itself.

 

Is it possible you got the wrong pulley?

 

I actually only replaced the bearing inside of the pulley. Comes out pretty easy with a little gentle persuasion from a hammer and a socket. My tensioner is different though because my car is a 2012 and has a traditional power steering pump. I guess the new ones must have an electric PS pump and so the belt routes differently. In this video, the blank space to the left of the alternator is where my PS pump is. My tensioner is spring loaded and non-adjustable

 

It's funny your avatar is a cat but your name is about turtles? Is your cat named turtles?

 

Just in case anyone finds this via google search because they have a rattle in the front of their gen 4 Subaru outback that isn't caused by the tensioner bearing, it was indeed the tensioner assembly. In my case the bearing was also bad, but replacing only the bearing did not fix the issue. Replaced the tensioner and it's quiet now, thanks everyone for your help.