Hi guys, I'm getting a rattle noise from the engine compartment in forward gear upon med acceleration. I don't hear it at wot or very little acceleration. It sounds like your typical rattle, but only does it in driver/ od. I checked for anything loose but everything is sold. I'm thinking smog pump pulley or ac pulley? The motor is an '89 TBI 305 or simply LO3. Let me know what you guys think. Thanks,
Adam

 

What work have you done to your engine lately. Any head work or anything like that?

 

Sounds like it could be a little bit of detonation. Have you tinkered with the timing lately?

 

I know for sure its not detonation. I've had this problem when the timing was 4 degrees retarded (retard mechanic) and now thats its 4 degrees advanced. Detonation usually is alot louder and occurs at high rpm or wot. At WOT, the motor revs normally without any abnormal noises.

 

Hey man, thats cool, I just wanted to throw that out there to ya. You never know sometimes you just get a little too much advance. I know this sounds a little funny, but if your car still has a cat, does it still have the heat shield over it? I have had a couple of people come to me with a rattle at mid RPM's, and have it be the shield on the cat rattling, that may be worth looking into. Good luck with it.

 

BTW, I like that. I have met a few of them in my lifetime too!

 

I haven't checked the heatshields since the cats are pretty new but I was thinking about looking back at the exhaust. Thanks for the suggestion.

 

I had a metallic flutter that I thought was a heat shield and it turned out to be loose rocker arms.

 

I was actually going to replace my valve seals and then end up adjusting rocker arms and all. But I'm still thinking more pulleys or smog.

 

Eliminate possible accessory drive noise by pulling the belt and taking it for a short drive.