YARIS 2005 Rattling sound

[mik23]

Hi

Try to explain the problem

1- start car
2-1st gear
3-accelerate (i heared a rattling sound from engine / belt side) not sure what / where
4-after couple of seconds sound disappear
5-change gear 2-3 again when accelerate there is sound for couple of second then disappears.

On idle car full rev no rattling sound at all check inside and at the bonnet.

shown it to a friend he said it is due to dry belt sprayed a XO solution possible a lubricant or something.

The sound disappear for 1-2 hr.

After that it came back again.

checked the belt no physical damage no unusual sound when on idle.

Any help would be highly appreciated.

cheers.