Valves, chains, or exhaust leak? OH NO (sound clip inside)

[dimeified]

Here is the NEW sound clip holding the recorder out of my window while parked.
http://mywebpages.comcast.net/dimeified/badnews2.wma
Throughout the clip im feathering the throttle. The rattling sound masks out the normal engine noise for the first half of the clip. Towards the end i raise the rev a little higher and you can hear the normal engine sound behind it as the revs raise.

1- It's been determined through exhaustive (no pun intended) work that the problem is not the cat or muffler. I removed cat and reinstalled cat-bypass. Used brand new gaskets. Wirewheeled flange surfaces on cat-bypass, muffler, and the 2 flanges that the cat connects to. Tightened muffler straps completely and backed off 2 turns. This is an mkexhaust 1st gen no baffling muffler, so that cant be the problem either.

2- It's not the alternator or fan. I have disconnected the fan belt and ac belts, sound was still there.

3- Held hose to chain boxes and ear during noise, did not hear anything alarming.

4- I also haven't had a valve adjust since i had the car 3 or 4 years ago.

5- I use mobil1 15w50 oil, oil level is at proper level.

6- Only happens when car is up to operating temps.

7- Easiest way to get problem to reoccur is driving at constant speed in the 3k rpm range. This may be sympathetic vibration from the motor or exhaust causing something else to rattle.

8 - It seems shifting has gotten harder the past couple days. The shift lever is harder to move, and moving into gears is a little more difficult. However the clutch pedal pushes down alot easier. Yesterday when shifting out of 2nd gear, the transmission threw it out for me, with great force.

Here is the old sound clip from in the cabin for reference.
http://mywebpages.comcast.net/dimeified/badnews.WMA

[flatsixnut]

Its hard to tell from the sound clip...its not very clear. From what I can hear, it sounds to solid to be an exhaust leak.

[kodioneill]

the only thing i can here is your shoes on the ground.

[Tim L]

It sounds like a rod bearing but could easily be an exhaust leak.

[carrera turbo]

i have listened to this a number of times and trying to determine what sounds your making and what the car is making is difficult for me. if it does it again and you want to make a recording set the recorder down on the ground in front of your rear tire this will keep some of the clutter down.
"sounds to me like a cheff preparing a meal while driving his porsche"

have you added oil since this clip? or have you done anything different ? as why is the noise no longer there.

hope you get this figured out as these kinda things are a bit worrysome for the driver.

cheers ed

[dimeified]

I did try adding oil, and i also let the gas tank run close to empty and refilled with fresh gas. Problem was still there for days. Should i use the right rear tire so the exhaust system doesn't bleed into the recording?

[carrera turbo]

that would be fine i just cant get a clear idea of what is really the car and what is you.

give us another try and lets see what we get.

cheers ed

[Dixie]

Check that the muffler straps are tight.

I had a rattle/buzz that would occur occasionally at startup. I spent hours trying to figure out what it was. Then I happened to notice the muffler strap was just loose enough that it could move.

[dimeified]

I've added a new sound clip for everyone to hear, this one is very detailed. Also, i have cleaned up my information in the thread, and put it all in the first post.