hey guys,
i took my boat out with the new 509 in it yesturday and it works great,after about 20minutes i noticed the temp gauge rising so i stopped and looked under the hatch to find the left head gasket leaking ans spraying water out from between the head and block between #1 and 3 cylinder and gasket gone right there,any ideas?i almost have this head off,i might pull both heads though,motor was just assembled???????????????

what gen block,,,, original heads? same gen heads as block?
correct head gaskets?

gen 5 502 block,pro topline alum.heads,felpro head gaskets that should be the right ones according to engine builder

when you get the heads off see how the gasket lines up to the water jackets,,,, common cause of leaks if the port is very close to the sealing edge

So many possibilities...

I'd look at the wrong head gasket to start. Remove the head bolts with a torque wrench set to about 65 ft/lbs. That will tell you if one of the bolts was missed during assembly or if one (or more) has a problem. Block deck needs to be checked with a machinists straghtedge and a feeler gauge as do the head surfaces.

Are the heads the original (real) Pro Toplines or are they the ripoff one's they're selling on Ebay under that name?

you will need to re-torgue after warning the engine and letting it cool...but a gen V and those heads require a certain head gasket, double ck that, read my earlier reply on head gaskets also...Rob