So I had a cooling issue with the Miata, and after I got that sorted I noticed a pretty god awful sound. I'm sure it was there beforehand, but I didn't notice it. It sounds like it is coming from the valvetrain, so I replaced the HLAs today.

That didn't work and the noise is still there. Here is the noise: http://dl.dropbox.com/u/10471269/Memo.m4a

I'm seriously stumped as to what it could be, and Miata.net is worthless for asking questions that aren't "do these sun visors make my car look fat?"

 

Sounds like an exhaust leak.

 

And all I need to fix that is a new exhaust gasket? Right?

 

Possibly, depends on where it is leaking from. I know absolutely nothing about your setup. Could be a cracked manifold, loose downpipe, loose turbo...

 

It's a 1994, completely stock.

 

did you remove the head at all? Did you remove the exhaust manifold?

 

Haven't removed the head, just valve cover. Haven't removed the exhaust manifold at all.

 

Here's a video: http://www.youtube.com/watch?v=OHAp2_0yNjA

 

that sounds more like a belt/pulley issue than an exhaust issue

edit: okay, i need you to tell me EXACTLY what you "fixed" to get your cooling issue sorted out... what work was done to the car between when it was shut down before the horrible sound to when it was started and had the new horrible sound? Hoses? Belts? Heat shields? Brake fluid? Nitrogen inflation?

 

When I was going down to CMP, I heard a light rattle on the freeway when acceleration. Sounded muted to what it is now.

My cooling issue was that the water inlet gasket **** the bed, so I ordered an ebay timing belt/water pump kit and replaced those along with a new radiator. Past month: new timing belt, new water pump, new radiator, new coolant, new radiator hoses, and as of today, new oil.

I'm pretty sure the sound existed before I did the major amount of maintenance.

 

You forgot to tighten your timing belt tensioner pulley.

And if you didn't forget, then your exhaust has cancer.

If it was your exhaust, the rhythm would sound like a hip hop club in downtown. Predictable, and never missing a beat.

Instead, it sounds like high school white boy rhythm, which is why I suggested it was a belt/pulley problem.