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03 Forester XS and I my girl's 04 Outback H6
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319 Posts
Discussion Starter · #1 ·
I recently had to drop the exhaust so I suspect an exhaust leak but I'm curious to hear some thoughts please.

The sound just goes away at about 0.25 seconds in that video.

I feel like I heard something like this before after doing the heads and once I tightened up the exhaust manifold better it went away.

I noticed it this morning on my way to work, all of a sudden it was super loud and within a minute it quieted back down.

I recently disconnected the exhaust at this point here:
Automotive tire Automotive exterior Tints and shades Gas Wood


I just now loosened and then tightened it further and the noise still happened again. I'm not sure if it's completely sealed as that part seems pretty rusty and flaky so I suspect it's not sealing all the way.

I'm going to completely loosen it, try reseating it and tightening to see if it goes away.

Whatch ya'll think?

Thanks!
 

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2003 Forester 2.5X 5MT & 2008 Impreza WRX 5MT & 2009 Impreza 2.5i 5MT
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325 Posts
Yeah there should be a gasket there like Mr.AC pointed out. Probably a donut gasket. I would check Napa Auto for the proper gasket. You may need to replace that gasket and it uses a spring and bolt kit. If your bolts are bad you may want to replace them too.
 

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2008 LL Bean (4EAT)
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5,244 Posts
The sound seems to be coming from the engine, and an exhaust leak would not sound or stop suddenly like that.
The exhaust joint should have a solid steel gasket like a donut or O-ring that fits into the flared flanges of each pipe. P/N 44022AA123
The flange bolts have springs whose compression allows sealing with some movement of each pipe around the joint. The joint is not tightened until the exhaust system is hanging freely in its hangers without stress.
No point in tightening a joint that may not have a gasket, as the flanges cannot seal without the gasket.
 

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03 Forester XS and I my girl's 04 Outback H6
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319 Posts
Discussion Starter · #5 · (Edited)
It definitely has the donut gasket in there. It’s just old and flaking apart so I’m tempted to replace it. I unbolted it entirely last night and reseated it. Got it seated decently and held it together with vice grips while bolted it again. Better than my first attempt by hand. How would I know I need new spring and bolts?
sound seems to be coming from the engine, and an exhaust leak would not sound or stop suddenly like that.
I was afraid it was coming from the engine. How to diagnose it? Any thoughts what it could be making that sound?
The sound seems better after reseating the flange on the flaking donut gasket.

Could this sound be what people call engine knock? I’m about to change the oil and get a genuine Subaru oil filter in there.
 

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03 Forester XS and I my girl's 04 Outback H6
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319 Posts
Discussion Starter · #6 ·
Here is a clip of how the engine sounds today once I got to work. The engine was already warm by this point. Any thing sound off? I don’t have the best ear for it but it sounds alright to me. Maybe one of y’all hear something I don’t:
 

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03 Forester XS and I my girl's 04 Outback H6
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319 Posts
Discussion Starter · #8 ·
Put a plastic hose to your ear and try to pinpoint where the sounds is coming from. I’m not a mechanic but sounds to me like a ball bearing.
Great idea! I’m no mechanic either. Where is this potential ball bearing located? If it’s the culprit is that an easy repair or does it require tearing the engine apart?
 

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2022 Subaru Forester sport.
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22 Posts
Sounds to me that is coming from the alternator. Easy fix and no engine tear down needed.
The most important thing is to locate where is coming from and take it from there. Step by step man. I would also check for any bolts, nuts, fasteners and such missing or loose, any loose components also. Sound has its own way of traveling and often times is not located where you think.
 

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03 Forester XS and I my girl's 04 Outback H6
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319 Posts
Discussion Starter · #11 ·
Seems like you found your problem. Hopefully that was all it took.
I really hoped so but the sound returned. And like it usually does, the sound quickly goes away after about 30 seconds to a minute. I got it on video again:
Could it be related to the serpentine belt?
I have not yet tightened the nut on tensioner pulley. I needed to get a wrench that could fit in there. Probably gonna replace the belts too. Could the lack of tightness on the tensioner pulley or the age of the belts be throwing off a bearing in the alternator or anything else spinning on there? It’s quite curious that the issue only appears for such a short period of time.
 

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'14 Forester XT Touring
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1,304 Posts
Well that sucks.
I'm scratching my head around these one. The problem does go way that's the mystery.
If it was a lose pully or bad ball bearing it shouldn't fix itself after awhile.
Odd one indeed.
 
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