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i thought i had a fuel or electrical problem,,,but eveything keeps checking out,,,now iam thinking i have a small water leak at the manifold riser gasket,,,the engine starts and run pretty good,,,,but after a run,,,and going to idle it stalls,,,and wont restart,,,or if it does it runs poorly,,,other engine is good,,i want to start the engine on the rack with belt disconnected,,,to see if my problem clears up,,,if it does than ill know it has something to do with water getting in,,,how many min. max can i run the engine with no water hooked up,,and alt belt off,,that engine also had steam coming from the tailpipes,,didnt see any from the engine that was running good,,,,if i did have a small leak is it possible that i didnt do any damage to the engine ,,,or is it a matter of time before a blow up???496 mag engines,,,or anybody have some advice

First,

You can run the engine with no water/no belt for brief periods but problem is you will burn up exhaust hoses if in the boat. Just make sure you watch the coolant temp on the computer if it's out of the boat.. If you have dry exhaust all the way out then a little longer

Regarding the steam vs no steam, make sure both of the plastic handle valves on the bottom of the manifolds are closed. For some reason, lots of people seem to think these should be open but they are supposed to be closed. Unless you're draining for winter etc..

Finally, if you suspect water getting in the engine DON"T run it until you figure it out. If it's out on the ground and maybe sitting on a bit of a slope then you could be causing the problem and/or making it worse. If you ever suspect water intrusion, firing it up is NOT the way to diagnose the suspicion. Also, it's possible that if the boat is backed slightly up a hill in your drive way you could be taking away the angle of the down exhaust path. Is the boat left in the water?

Before pulling the manifolds off, very carefully "lean" them outward as you loosen bolts and keep leaning before pulling them away from the heads. If there is any standing water in the exhaust, this would help insure that you don't dump it all the way in. You'll see water trails if it's sucking.

Also, there is no way water can leak between the riser and manifold. It's a dry joint. If you are somehow seeing water coming from inbetween the riser and manifold than it's coming back up the exhaust. Of course, I guess it's always possible that one of the parts could have a crack in it... Take your time and work through it before assuming anything.

the first gasket we pulled off was bad,,,ill looks at the other three tonight,,,iam thinking it was pulling in some water,,causing the engine to not start after a run,,if its not that,, ill have to put a computer on it,,,