have a 502 with 550hp, watercooled headers had broken exhaust valve on rear cylinder#8 new piston new valve every thing checked out at motor shop, put back in water ran for ten min broke exaust valve rear cylinder other side now bad piston and head I am afraid to fix again could their be a problem I am not aware of could water be getting into exaust port from my headers to snap a hot valve. iron eagle heads mot built at motor shop please help.

Do you have cmi's? You are new here and the problem with them is pretty well known. You need to pressure check your headers. Mine got a crack and broke a valve. Not fun especially since it was scheduled for a check up the next day. If you have a leak go to a manifold style set up and be worry free.

thanks dont know what style headers I have, big black ones on the bottom there are waterline hoses that go to the thermostat area, dont know much about howthey work, there off the boat I will take a better look at them. does the water actually mix with the exaust or is it seprate in the header

1st take pics of them and either join here as a paying member or put the pics on a picture site I think its called maybe someone can explain better than me on pics. if you find out they are leaking call DIAMOND PERFORMANCE MARINE =Bill at 302 521 0123 Bill has the best prices around for anything marine he carrys hardin marine exhaust which has 3 different headers plus the gil marine exhaust plus he has CMI headers and stainless marine exhaust which has lasted me 13years. but now I have hardin hurricane headers on my new boat which are nice. the stainless marine are manifolds and ss tubes in 4''/ 4 1/2'' /and 5''. hardin has real fancy headers all polished and seem to hold up nice. cmi headers have had issues my friends needed to be rewelded after 4years his standard ones another just blew up his turbo motor cause of leaking cmi headers and these were the split tops not 525 ones. so get us pic please if there black steel they might be lightning headers. but call bill I would not buy used headers but would buy used manifold style exhaust like SM. I did back in 1994 they were 6months old still work on my 509 650hp.

thank you everyone for you input new to this chat thing going to be come a paid member. Lots of differnt sugestions on my breaking exaust valves from bad headers to bad valves, was told only exaust valve to use would a inganol valve 100 a piece the valves I have are a 30 dollar valve any sugestions on this mess i have