4 K Q noise pebbles in a can

[auditodd at attbi.com]

I would be willing to bet a beer that the catalytic converter guts have
separated from the shell and are bouncing around inside.

I know from experience.
>
> My guess is the exhaust.
> I think mine does it but its not that loud.
> Vibrations from load and near stalling, I think.
> Loose Cat innards, broken hangers?
> Just a guess - Scott in BOSTON
>
> On my 4kq there is a noise i cannot figure out anyone's help would be great.
>
> When I let out on my clutch in 1st gear from a stop and let the engine rpm
> fall below 800 rpm i get a "pebbles in a tin can" rattle.  At first I
> thought
> replacing the water pump would get rid of this because at normal idle i
> could
> hear the sound constantly.  After replacing the water pump the sound went
> away at normal idle and found that the water pump had bad bearings. I did
> overtighten the new water pump tension were the belt could only twist just
> 45
> degrees instead of 90 degrees. I went about 250 miles on the tension until i
> slacked the belt to the approved 90 degrees.  Did the tension kill the water
> pump bearing?    However the sound now only occurs now when you let out on
> the clutch in 1st gear still.
> What else could be?  Clutch?  Another Water Pump bearing shot?  Engine
> knock?
>  Help!!
>