I have a 1991 f-150 with a 302 and 145,000. The engine is not in the best of shape, it still blows oil into the air filter after replacing the pcv. It is starting to pin again. Anyway, I noicted a coolant leak and we could not find it. The clear coolant reservoir does not seem to be cracked but coolant seems like its coming out of the top and running down the reservoir. Is this possible? I know the pressures in the engine are messed up. Any fixes short of rebuilding? Thanks.

 

Is the resovoir over filled? IF there is too much coolant in the resovoir it will come out as the engine warms because as the coolant expands/pressure builds it fills the resovoir up some. later

 

Like jwtaylor said, if it's over filled it will overflow as it warms up. But if you see bubbles in the resevoir blowing the coolant out, then you may have a blown head gasket.