Originally Posted by
DSMMH
The only other thing I can think of that would make a noise approximately 30 seconds after start with the belt off is the low pressure oil pump.
Did you have normal oil pressure when it ran for 30 seconds?
Sounds like the LPOP has lost suction for some reason. If it did and the motor locked, then your motor is probably toast.
DSMMH
Im thinking the op may have droped a bolt down in the intake port. or soemthing along those lines.