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Discussion Starter #1
Hey guys, I am curious what specifically is causing this noise, and if it is easily fixable. Here is a video, where the noise becomes clear ~:05 seconds in. It is relatively loud for the first couple minutes, and quiets down a bit once the engine gets warm, although the sound never seems to entirely go away.

Anyone know what could be causing this, and if there is anything I can do about it?
 

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03 H6 OBW & 06 WRX Sportwagon
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exhaust manifold leak?

I dunno what I'm hearing.

Is it central or louder on oneside vs the other?

you could 'briefly', idle the engine with the belts removed. Then see if it sounds the same.
 

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Onyx, 2008 LL Bean 3.0R and 2017 Honda Civic Hatchback Sport Touring
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My vote is for alternator pulley bearings. Like 1 Lucky said above - remove the belts and let it run for a minute without them. If you don't hear the noise then you know it is belt related due to the process of elimination. If you do hear the noise with the belts off, then it is something engine related, like a failing timing belt pulley. Given a choice, I vote the alternator pulley bearings. Much easier to get to. :)
 

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Go to an auto supply and buy a cheap stethoscope. You'd be amazed at what you can pinpoint. if you place it on your alternator you'll hear the bearings, if you place it on the motor you can pinpoint which lifter is noisy.
 

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Discussion Starter #5
Is there an easy method to remove the belts? They are super secure and the last thing I want to do is try to force them...

On another note, while scoping around the engine compartment I found this screw (the one marked with a '9') that was completely loose, and came right out when I pulled it. The noise seems to be emanating from right around this area... Could this be related? Anyone know what this is?



 

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Discussion Starter #7
Man, you scared me for a second! I did a google image search, and all the pics I found of a 99 OBW engine have this same bolt without a pulley attached. Still, I'm sure it shouldn't be falling out...

 

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2009 Tribeca Now - 2004 Outback EJ259 - Sold
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That bolt you pulled out should be threaded into and holding the RH side of the alternator.
The long threaded bolt through it is used to apply tension to the belt then the bolt is tightened to hold it.
Either someone forgot to tighten it, or they stripped the threads out of the alternator (which can happen, especially if it was crossthreaded.)
Explains the squeaky belt when the alternator is loaded & tries to output current, or the power steering pump.

1 Lucky you posted up the tensioner for the other belt running the A/C.
 

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The tensioner/pulley that 1 Lucky Texan refers to (and pictured above) is for the AC compressor drive belt. It's visible in the last photo above, down and to the right (about 4:00 O'Clock) of the blue, hand-drawn circle.

The short bolt that is loose is part of the alternator/p.s. pump belt tensioner (circled in red in the next-to-last photo above). The long screw with the hex head at the top is used to raise or lower the block that the short bolt is set into. The short bolt goes through the block and into a threaded hole on the alternator frame. When the long screw is turned, it raises and lowers the block, and because the short bolt is screwed into the alternator frame, the alternator is moved up and down, thereby adjusting the drive belt tension. When the belt adjustment is set, the short bolt is then tightened, which pulls the alternator frame against the adjuster frame (attached to the engine block) and locks the alternator in position.

With the short bolt out, there's nothing to hold the alternator in position other than the tightness of the alternator mounting bolt at the other side. The alternator has probably dropped drop down a bit on the left side, and the noise is the loose alternator drive belt slipping.

[edit: guess I doubled with ntippet . . . .]
 

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Discussion Starter #11
I got the bolt back in there and raised the alternator about a 1/2", which got rid of the noise too :D

I have always been intimidated by the complexity of my car's guts, but every time I try to fix something myself it is MUCH easier than I had anticipated. This forum has definitely saved me a couple hundred in mechanic fees over the last couple weeks! Thanks a ton!!
 
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