weird sounds when car moves

[Donovan]

ok well i own a 1987 toyota supra turbo 5 spd well when i drive the vehicle like almost every single ime when i start it right up and when i come from a stop and start moving there is this weird sound coming from it seems like under the car it sounds like a clacking sound with something hitting together like a rub with grinding and one more problem i am having is that when i purchased the car i could smell antifreeze but the guy said the smell was coming from the over flow tank that fills up with the antifreeze cause it does not have a seal on it to hold the lid on to the top of it so it always falls off but the rubber tube stays inside the housing of the resivore but its just doesnt let the cap seal shut could that be where i am getting the antifreeze smell from or dont tell me but could it be that my car is geting close to a BHG!!?