Guns

So I bought a jet boat with 455 olds looked great on the outside. The guy selling it didn't know much about it and in no was was mechanically inclined. The engine was super clean not a drop of oil anywhere. But he had it for awhile and never got it running. So when I got it home decided to pull it apart, because it was winter time and figured better just ordered a gasket kit and reseal it. I didn't want any problems on the water. Pulled heads, cam, and oil pan it looked brand new inside still had the cross hatch marks. So put it all back together matched the head gasket with old one to make sure I had the right one. The intake didn't have a valley pan but I used it instead. Every thing went fine primed the engine fired up on fist crank.

Then it all went bad seen excessive smoke coming out of valve cover breather then I seen water coming out of the weep holes in the header ran for about a minute. Jet boats headers have water running through them, and the holes let water that didn't make it up the header Escape. But I didn't have any water going to them, the lines were not connected. So I got water in my oil now and water dripping out of my exhaust on cylinder 3 or 5. I have great compression across all cylinders no water in them. I checked the heads and block with precision parallels before I reassemble. If I run water though the engine water drips out the holes even when the engine is not running. Someone please help tell me I forgot something simple. I wonder why it only leaks on one side of the block.

oldcutlass

I'm confused as to what you used for an intake gasket. Not 100% familiar with boat engines but doesn't the water circulate through the block and exhaust manifolds?

tru-blue 442

I'm wondering if he forgot to use sealant around the water ports of the intake valley
pan gasket. Also on marine used engines, if they sit with water in them and are susceptible
to freezing, bad things can happen with the blocks and or the heads.

Oldsmaniac

You may want to be sure the timing chain cover is not pitted with a pin hole where the water pump bolts on. A pin hole here will let water into the crankcase.

Professur

Super clean .. and doesn't know much about it. No better signal to keep walking.

Guns

Yeah should have kept waking but it was so cheap figured cant lose. You couldn't buy the carb for what I paid for the boat. I'm just going to have to pull it back apart the water in the header is what has me wondering. Water in exhaust port but not in the cylinder. I used the metal intake gasket with the valley pan and put silicone around water and lightly around intake ports.

Guns

Fun71

I'm in the same boat (ha!) as oldcutlass and don't know anything about jet boat setups, but that should narrow down the possible fault locations. Perhaps a crack in the head between the exhaust port and the water jacket?

oldcutlass

It sounds like the turkey tray gasket didn't lay flat and the bosses were not seated on one side. I this application you may want to just use a set of good aftermarket intake gaskets.