Oh man, that thing will leak bad if you don't have the thick o-ring/ gasket in there. I first used the small o-ring that came with a Felpro engine gasket kit (maybe it was for something else I'm thinking now , but upon initial fire up it was leaking bad right there. I even snugged up that long water pump to intake bolt first. Then since it was spewing out I cranked down on that bolt and it snapped. Had to remove intake and get the busted bolt out. I then used an intake gasket set from NAPA which has a real thick o-ring and no sealant. No leaks at all. Never take for granted the o-ring. NASA learned that the hard way as well...