496 Mag HO water in the cylinders. How?
 

at first I thought that I had a bad starter, as the engine would not roll over or budge for that matter and ruled out batteries being the prob as the other engine acts just fine. as determined there is only three possibilities of getting water in the cylinders, 1) manifold leak, 2) riser leak, 3) water entry from the lake in the exhaust pipe. I have pressure tested the manifold at 20lbs. and no leaks. I have given visual inspection to riser and will repressurize the manifold and riser tomorrow while applying heat. this is a 32' sunsation dominator with the built in swim platform. What is the likelihood of water coming up the exhaust and filling the cylinders?. it ran fine and I shut it off. I was out in the lake not at the sand bar. it wasn't all that rough. just cannot take a chance on this happening again and bending a rod.

Are u running stock exhaust?

yes

what's the likely hood that there is engine damage. who out there has experience with this happening and what was the outcome? The engine did not fire with water in the cylinders that I know of. How common is it that reversion of water going up the exhaust pipe happens and putting water into the cylinders?

what kind of exhaust tips are you running??straight cut with extrernal flappers?or angle cut with internal flappers?,,are the flappers good or are they missing?,are the flappers in the Y pipe there or did they burn off??

496 is a closed cooling engine ,,if you had internal engine leaks it would be antifreeze not water,,sounds like your issue is exhuast related,,,
could you have bent a rod when you hydrolocked the engine??yes,,but the only way you will know without taking it apart is by running it and feel for a miss,viabration ,,noise...but you might also be ok,,wont know till you run it

As i said in the last post re this my friends did the same thing many years ago ,he tried to crank it 3or 4 times befor i got to his boat and stoped him , he was luckey we did the fix and boat ran great for many years ,so you too could be luckey .

hoping for the best of luck there. the flapper are all in tack. they are straight cut pipes with the black external rubber flappers. they do hang open on the bottom and would imagine that the water could have forced them open. I am going to have the manifold and riser die checked and heat the runners as I pressure test to 40lbs to rule out cracks later this week. when I attempted to start the engine it was locked. If the water got in while the engine was off it could have only entered an open exhaust valve, so during the start attempt it should have rolled until the exhaust valve closed and compression began until hyro lock. strange though it ran perfectly fine til it was shut off. very puzzeling. I will do the best I can to rule out the crack thing and put it back together and try it on the trailer. I will run it until fully heated, then I will remove the plugs to see what I find. sickening. I just bought this boat and ran it for three hour's and this bull$hit.

Pull the plugs and see if it turns over.

it does

I had this issue last summer. Ended up being an exh manifold cracked internally.replaced it and changed the oil a few times and no issues since.

Is there any history or tell tale signs of overheating at one time? If the paint is crispy around the manifolds it might have gotten hot & cracked a manifold. How straight are the pipes coming out of the risers? Just trying to think the problem. Randy

I would spin it without the plugs, put the plugs back in it and fire it . The chances of bending a rod using the starter are slim ( you said you didn't think it fired).Bring it up to temp, shut it off and pull plugs. Let it sit overnight and spin it with the plugs out, look for water coming out of a cylinder. But that is just me.....

This happened to me last year. We were trailering the boat when it must've happened. The boat sat two weeks before we discovered the problem. As we tested the boat at home on the hose it would not turn over and made a sickening thunk.

I pulled the plugs and then manually turned the engine, flushing out a lot of water from one of the cylinders. Then it would spin freely with the starter. I changed the oil, oil filter and spark plugs. After that it ran fine and continues perfectly to this day.

I am not sure how the water got in but I figured that as we were shutting down the motor with the corsa exhaust on, a wave must've hit the back of the boat as it was getting onto the trailer.

Back to the flappers. Do you have internal and external flappers. You need both. Lift up the external flappers and shine a light up in the pipes. You should have internals also. If theyare gone it will just happen again if not replaced. Check your other engine also.

no internal flappers maybe turn the silent choice switch on. this would close the gap while sitting.

this is an ex salt water boat. I have seen numerous posts of these aluminum 496 manifolds rotted and leaking. I have to tell you I am scared to put this manifold back on. if it leaks that engine is done.

hmmmmmm......interesting. exactly what I had.

no over heating. the pipes have good angle on the trailer and even more in the water.

'05 might be cast iron instead of aluminum. All had stainless risers. Put a magnet to the manifold and see which you have.

what ever you do,,replace the exhaust tips with ones that have internal flappers...

+1. Buddy had a 2000 Dominator with the angle-cut Corsa tips with internal stainless flappers. No external rubber boots. Took a lot of waves into the transom on anchor at LOTO and never had a problem with getting water in the motors.

Just had same happen to me .... Still have not figured it out. Aft exhaust valve full of water after engine ran fine... Could not turn...