1988 Other Mitsubishi Models Need help in trying to determin

I was driving my 1988 Mitsubishi Van when I suddenly started to hear faint clicking noises coming from the engine just as I exited the freeway to find out what was causing it stalled and smoke started coming out from the engine compartment. I soon found out that the smoke was the result of oily greenish liquid splattered all over the hot motor and dripping away at the bottom--before any of this my engine oil light came on about a day ago and I had managed to pour a quart in there -then continued to drive it again. Until this happened. I think it could be a water pump or hose issue but im not sure until I know what else to look for, please give me some advice.