Ok, this is a new one for me.

Did an oil change on saturday. Castrol GTX, new oil filter (fram, yeah, I know...) no issues, no mistakes, had plenty of oil - drove it that day, it worked fine. Drove it sunday, also just fine and no problems at all. Today I drove the bike till this evening, decided to go for a quick drive to get some food, and it's making a horrible, horrible noise.

It literally sounds like a marble spinning around a can, if you can imagine that. Can't hear it at idle, but when you give it some gas you start hearing it around 1000 rpm, and it goes up in speed with RPM. When RPM drops back to idle, it lags behind a ways - it takes longer to 'spin down' than the engine does. Solidly loud, not hard to hear just driving around with the windows down. It definitely wasn't doing this on saturday or sunday evening.

Checked the oil, still very much on the upper portion of the good area. Nothing else leaking/broken that I can see. I'm going to get a noise sample tomorrow, but my camera batteries are charging. Anything anyone can think of to look at or especially try to sample before I do?

 

Do you still have Cats? That is a possibility that they have broken and and free-flowing inside the canister.

 

Yeah - stock catted y. I figured cats would be irregular though - this seems to be a bit more regular (but I could be remembering wrong).

 

kinda makes you wonder when something like this happens right after an oil change.

 

That's what I was actually thinking...

What's a spun bearing or the like sound like?

 

Did you change brands of oil? Are you running a viscosity for summer heat?

 

Nope - I live in colorado, drive year round, and she always gets Castrol GTX 5w-30.

ok - further notes while the video uploads.

Sound is definitely more noticeable when cold (temp gauge 1/2 way to normal). did NOT make the sound when I first started it ( I have video from then and from about 2 minutes later, when it started). Doesn't make the noise as much when you keep it in gear. I don't notice it with the radio on, so this may have been happening for a while. Seems to be from the engine bay.

 

Ok. Forgive the .mpg files (it's all my camera takes)

First one is cold idle - no sound.
www.lopoetve.com/images/firebirdtwo/firebird.MPG

Second one is 2 minutes later. Strange sound.
http://www.lopoetve.com/images/fireb.../firebird2.MPG

 

a spun bearing sounds more like a HORID knock, do you have any loss of power any other sypmtoms other then the noise? Hows the oil pressure?

 

Oil pressure is solid as a rock. Power is solid as well - if anything, it's ~up~ slightly.

 

weird, maybe you just spit the guts out of the cats, if you have stock cats there pretty close to the engine so it could sound like thats where its coming from. Also if it feels like the power is up goes along with this theory cause air is moving more freely through the exhaust. No SES light?

 

No SES light yet.

FWIW, the car has 38k. Original cats were replaced under warranty at 15k (O_O)... bad design?

 

its hard to tell from the video but you sure it isnt valvetrain related? Could you pull the valve covers, rocker arms, pushrods and inspect everything?

 

If they're aftermarket cats, they are a more likely issue.

 

supposedly they're GM cats - same as the original stockers.

 

Was anything else fixed when the cats were replaced? I ask, because cats don't just go bad!

 

Cats, spark plugs, fuel pump were all within a couple thousand miles, according to the maint. history, IIRC.

5/15/2003 081459 # H0127 - FRONT BRAKE ROTOR REPLACEMENT - BOTH 15086 miles
01/13/2003 131616 # L2300 - CONVERTER, OXIDATION CATALYTIC - REPLACE 14828 miles
01/03/2003 131135 # L1200 - FUEL TANK FUEL PUMP MODULE REPLACEMENT 14812 miles
01/03/2003 131135 # J4226 - SPARK PLUG REPLACEMENT 14812 miles
03/21/2002 097868 # E7200 - IGNITION LOCK CYLINDER REPLACEMENT 6162 miles
12/11/2000 A31746 I Z7000 - PRE-DELIVERY INSPECTION - BASE TIME 0 miles

 

If I knew how, I could... I'm not sure I have the experience to even start with that (I don't have the foggiest clue how to even start pulling that stuff out)

 

The video isnt working for me...but have you tried pushing the clutch in to see if it changes the noise at all?

EDIT:

Just loaded the video and it worked...probably not clutch related but its hard to tell in the vid.

 

clutch doesn't make any notable change in sound. Thought of the flywheel and tried that last night.