Leaking antifreeze

[bmoebonanza76]

Ok I got a 76 Bonanza with whats suppose to be a 400 engine. The problem is it runs kinda rough but you can drive down the road at 55 and it runs like a top. but the main problem is that it leaks antifreeze out of the front end of the engine somewhere like if it sits for a week or more it looses alot of water I can look under the engine and see where there is a drip but it's so greesy and dirty under there I have no clue where it's comming from Could it be the water pump? Cracked heads? cracked block? Or should i just pull the whole engine and just overhaul the 400? Give me your inputs It doesn't apear to loose any water when you drive it regularally.