Vibrating sound coming from underneath the car

[xAgentP]

its probably the exhaust. What could be causing the vibrating noise? I'm not even sure its a vibrating noise, that's just a guess. I dont really know what to call the sound, it might be clicking? The thing is, its loudest when it first start but then it gets a little quieter as I drive it. Is this the infamous "piston slap"? how can I be sure its not something else?

Besides that, there's a humming sound, this only lasts for a minute then goes away when the car is warmed up.

I know it can't be the cutout because I fastened that pretty tight a long time ago.

LS1, m6, 98, cutout, lid, powerplate

[SSpdDmon]

its probably the exhaust. What could be causing the vibrating noise? I'm not even sure its a vibrating noise, that's just a guess. I dont really know what to call the sound, it might be clicking? The thing is, its loudest when it first start but then it gets a little quieter as I drive it. Is this the infamous "piston slap"? how can I be sure its not something else?

Besides that, there's a humming sound, this only lasts for a minute then goes away when the car is warmed up.

I know it can't be the cutout because I fastened that pretty tight a long time ago.

LS1, m6, 98, cutout, lid, powerplate

Higher pitched humming on start up is most likely the AIR pump. Stick your ear behind the driver's side head light (hood up). If this is where it's coming from...it's the AIR pump.

Piston slap will go away as the motor warms up. The best way to describe it is, it sounds kind of like a diesel truck. If your f-body sounds kinda like the big yellow school bus used to on cold starts, that's piston slap.

What kind of oil are you using? I usually recommend Castrol Syntec 5w30 if you live where the temps get below 20*F and 10w30 if not (or if it's summer time).