werid sound

http://f1.pg.briefcase.yahoo.com/bc/qui ... yahoo.com/

this link is the a clip of my car. I told everyone before about a month ago that I kept on hearing a strange noise everytime I pushed the gas to a certain rpm and that it kept on getting louder. I have noticed this sound for the past 6 months at least and yesterday after I took this clip the car was at a temp of near 200 degrees due to the fact that I drove it in 100 degree weather. I checked the timing and it is around 10 BTDC and I have put 91 octane in my car but that noise did not change.

Yesterday I did also notice something else, the car seemed to change its point where u can start hearing the noise like when it is 150 degrees you can start to hear it at 2100 or 2200 rpm, but when like 200 u can hear it around 1700 or 1800 rpm which is where I heard this noise when I took this clip. I just dont know what is wrong, is it lifter tap, knocking, detonation?? I have good wires, fuel, air, spark, coil, cap, oil in the car but dont know what this noise is.

I dont know how long it will take to load it being 3 megs of clip. it may take a few min but please be patient, I will do what I can to make one smaller or take less time to download. thank you though

Please I need to know what is wrong with my car.

describe the sound...knocking? ticking? rattling? humming...

this is for those who cant wait long enuff for loading of sound

I tried to describe it but I got no where with an answer from anyone and I tried what people did tell me was check the timing and up the octane, zero results from both.

I think that sound is something mechanical, not related to fuel or timing. From what I can tell from the sound clip, it sounds like it may get louder with engine speed, but it doesn't really seem to change "speed" with the engine RPM, does it?

The two keys to figuring out stuff like this are localization if possible (sometimes using a stethescope or the like), and figuring out if a sound is speed-related or not (does the speed of a recurring sound increase equal with engine speed- crank & related moving parts related, twice the engine speed- camshaft and related parts, etc.).

I've successfully diagnosed bad main bearings, bad rod bearings, excessive thrust wear, piston slap, floppy timing chains, collapsed lifters, cracked flexplates, bad water pump/alternators/sterring pumps, etc. with these techniques).

as the changes in speed and things I am not sure about that, I think that it is constant with everything, but I do also know that from what you can see from yourself when the rpm increases the engine does not shake at all it smoothens out.

when I am on the road like going 70 mph and let off the gas I hear it really making that noise except its a little different more like a rattle instead of the knock. what kind of mechanical problem would allow the cars preformance to remain the same, gas milege the same, and engine not shaking??

It almost sounds like something metallic spinning loose on a shaft. That would make a noise which would be independent of engine speed, to a degree. There are a couple of things which can come loose to do that.

First, check the alternator fan and pulley. There is not much holding the fan and if it comes loose it will freewheel and make a noise sort of like that.

The other possibility is the slinger behind the crank damper. It's another little metal ring that could freewheel and make a constant chinging, chirping sound.

Another is the water pump impeller. It's only pressed on, an if it comes loose, could make the same loose, metallic freewheeling sound.

On the other end of the pump is the fan hub, but I wouldn't bet on that, but if you have a fan clutch, it could also make that kind of sound.

PS pulley?

I will be sure to check all that about the fan pulley idea that kind coincides with the fact that I changed alternator pulleys this xmas and that is when I really started to notice this noise. interestin, doubt it is that easy, but thanks.

about te video clip, sorry it takes so long to download and hope everyone got to hear to to give me an idea what is wrong. I can make more clips of me driving my car just for fun or perhaps show off my brothers car on here: 1993 probe gt buts its fast in its own way lol. I just need some help on putting those clips on here without much fuss. if I can get some help with that that would be great, ok.

Is the sound coming from front or back of the engine?
Something is going on when the engine comes off torque for sure.
If it's the back, I'd check the bell-housing bolts, the block plate, the starter bolts, and the flywheel/converter. It souds like a high speed metel on metal rub when the torque load comes of the engine.
When you changed alterantor pulleys did you use a big impact wrench? That's about the only way to change those slip fit pulleys without bending up the fan (there are al$o $pecial tool$, but...). See if the alt fan is loose, as Jack said, or maybe one of the alt fan blades is bent and scraping the alt case or a mounting bracket. Since the noise appears when the engine unloads (in the clip any way), watch to see how close the front belt driven components move as the engine torques to the side.
Fuel pump arm?
Timing chain slapping?
Rick(wrench)