Recently when I start my car and let it run it will make this rattling sound from the passeger side middle of car. It sounds like a marble in an empty paint can that is being shaken softly... Doesn't seem to be affecting performance and also seems to go away when the vehicle is warmed up Most of the time. Anyone have an idea what this is.. the noise is hard to hear while inside the car but very easily heard from outside..thanks,BEau

 

You might want to tell us the year make and model of the car, as well as any mods.

Could it be valvetrain noise?

 

Is it a standard tranny? The throwout bearing kinda sounds like that.

 

I have this noise too but never knew how to describe the sound . I always thought that it may be the cat converter, but what 96ss said would make a lot of sense, at least in my case with me having t.o. bearing issues on an M6.

 

Have you recently dropped an empty paint can with a marble inside your engine bay recently???

 

Sounds like a lifter getting old and taking a while to pump up.

 

My thoughts exactly. Valvetrain noise. The valvetrain is actually pretty noisy even whan it is new. That is why Corvettes switched to the composite valvecovers in 1993. They were better at masking the noisy valvetrain.

 

yep, ive noticed that sound for a little while from my 94 Z, cant hear it over the exhuast now.. but before that i noticed it every morning while it was cold, goes away completely after it warms up and everyone i asked about it said the same thing these guys did, one person said a loose rocker arm but i guess thats along the same lines.

 

I can't remember, do your cats/cat have them little welded on heat shields? Those welds tend to break and the damn thing rattles against the exhaust and car sometimes too. Maybe that was just a Mustang thing, but, worth a look-see.

 

everything needs to warm up and expand...