Exhaust buzzing/metal sound (video and picture in 4th post)

[98civex]

Hey guys so I've had this really annoying metal squeak coming from the exhaust if the car bucked a bit or when shifting gears. Started when intermidate pipe was replaced a year ago and along with it a new sturdier aftermarket exhaust hanger from autozone was put in. All stock exhaust btw

I kept the original Honda one with the "up" indicator on it. For a while I wondered if that somehow caused the noise I was hearing.

So yesterday during an oil change I decided for fun to swap it out with the original, and to my surprise the noise is gone. But I don't understand why that'd be? It's just a rubber hanger

 

[HeX]

Well, perhaps the stiffer one caused one of the exhaust joint to vibrate too much and rattle, maybe due to a loose or improperly mounted bolt or flange. Without any pictures, all any of us can do is guess.

 

[98civex]

Ok now I'm noticing a buzz/metal rattle when I accelerate. Idk what's going on. Can't reproduce it during idle and revving engine when it's on a lift and it doesn't look like there's any loose heat shields or metal touching anywhere.

Should I put the other hanger back on?

 

[98civex]

Here's a quick video right under driver's side. You can kind of hear what I'm talking about at idle while quickly revving the engine.

Also wondering if this rubber muffler hanger not being straight can contribute to the noise?

 

[HeX]

I dont really hear it, but have you inspected the exhaust manifold heat shield & screws?

 

[98civex]

Yes it seems solid that was first place I checked

 

[HeX]

What about your catalytic? Is it old enough that the innards may be loosening and rattling?

 

[98civex]

Its stock with 170k

Last year the mid pipe was replaced and the flange on the cat muffler side was repaired by an exhaust shop that welded a flange in.

Not sure if that misaligned the exhaust maybe?

 

[HeX]

I lean more towards the catalytic being the culprit being that its original.

 

[98civex]

So I noticed the spring bolts on the cat converter engine side are rotted and the heads can be moved with my finger. I'm thinking this has the be where the noise is coming from. I'd imagine you shouldn't be able to move the head without tools lol.

Question: should I replace the cat or see if a shop can weld in a flange to save money?

 

[HeX]

A muffler shop should likely be able to inspect it for free so you can make a better decision.

 

[98civex]

They quoted me $90 to weld in a flange on the header down pipe. Cat side seems fine. Here's a pic. Surprised it's even still attached. Should I go through with it or replace the pipe?

 

[98civex]

They said they'd weld a new flange on the cat too but it's fine. I don't know if I trust that for some reason. What if the process clogs it up or something

 

[HeX]

That is not a $90 job. That shop is trying to take you for a sucker and charge a full hours repair. Visit other muffler shops as another should offer to do it for $30-$40, maybe even less. Its an easy 15 minute job and that includes raising it on the lift.

 

[98civex]

Interesting. Thanks I'll shop around.

I'm curious, is there a reason the flanges are offset? Rather than being more horizontal where the bolts meet. Is it designed like that for a reason?

 

[HeX]

I assume the diagonal offset allows a little better vertical stability on the seal when the car bounces around natural whereas a horizontally even setup would create far more stress on the bolts. Thats my theory.

 

[98civex]

Yeah I wonder if when the flanges get replace whether they'll keep that offset or if it'll cause more problems down the road

 

[98civex]

So they actually didn't replace the bad flange, they cut both out (even the good one on the converter) and welded in a small flex pipe.

I'm weary of this, and wasn't what they originally said so they only charged me $40. But now if the cat goes I'll need it cut and welded in. I'm pissed

 

[HeX]

Is the rattle gone now? I definitely wouldnt be happy with a final product I didnt approve, but as rusty as the pipes & cat appear, you may just need to replace the piping anyways once the cat bites the dust.

 

[98civex]

True true. Yeah the noise is gone and I couldn't even tell my car was idling at one point lol.