Need more info on the characteristics of the sound. Does it change as you increase RPM? (ie. it disappears/gets louder/increases in pitch, etc.) The more specifics we have, the better we can help you.
About the coolant leak, unless you can really see the crack on the block itself, it may also be caused by a blown head gasket.
That crack worries me. The noise and the crack may be related. It's hard to be certain without actually looking at the engine.
Other noise sources off the top of my head that may match your description would be:
1. Loose timing belt or drive belt, flapping/vibrating
2. Related to #1, the tiiming cams may be altogether off. This can happen if the timing belt jumped a tooth. This may cause extensive damage, may be the reason for the crack
3. An exhaust leak
sir oj88, aga cruz, bambino and speedyfix,
thanks a lot, anyway now lang ulit ako nakpag reply because im too busy. Wala na yung car ko, binigay ko nalang sa relatives ko, kasi check nga mekaniko talaga may sira na yung engine block. Pero hindi naman daw gaano problem yun kasi maliit lang naman. At yung sound hindi ko na pinaayos. Ayun pinag tiyagaan nila. thanks a lot again mga sir.