Stupid engine rebuild

[TitanTn]

So I thought everything was fine. Wrong.

Started at the lake, ran like butter at the ramp. Drove about 5 minutes away and turned it off. Floated for about 5 minutes and tried to recrank. Turned over for a few seconds and then stopped. Couldn't get it to turn over anymore. Pulled the plugs and the cylinders are full of water. The oil is pristine. The water is in all cylinders, but mainly in the front two on each side. After clearing most of the water it never seemed to completely get it all, kinda like it was still entering however it's getting in.

Any ideas?

For those that haven't been following my story, the engine was rebuilt this winter. The block and heads have been fluxed. New guides and seats. Valve job. All new bottom end. New gaskets. 22 hours on the rebuild.

[supraaddict]

This might be a stupid question, but did you do anything different with the exhaust?

[ssa]

First thing I think I would check is the manifold to riser gaskets for leaks.

[TitanTn]

This might be a stupid question, but did you do anything different with the exhaust?

There are no dumb questions. Just a dumb boat that I'm sick of wrenching on. No, I didn't do anything different with the exhaust. The manifolds are somewhere around 6 years old I'm guessing. The previous owner bought them, so I don't know exactly.

First thing I think I would check is the manifold to riser gaskets for leaks.

I did a visual inspection when I had them off this winter and cleaned them out. They're not that old, and because this is happening to ALL cylinders I don't think I've had a failure on both manifolds at exactly the same time. I'm wondering if it's the intake in some way.

[michael hunter]

Check the intake manifold. Did you have the heads milled?

[TitanTn]

Check the intake manifold. Did you have the heads milled?

I'm walking down to the barn right now to pull the intake manifold. I'm not sure if damage will be visible to the eye or if I'll have to get it tested somehow. And yes, the heads were milled.

[cadunkle]

Odd for both manifolds or risers to fail at the same time, and I'd imagine given the angle of the engine it would be more likely to fill the cylinders towards the rear rather than the front. It's possible it could be intake leaking coolant passages to adjacent intake ports, though unlikely as it would likely leak into the valley and oil as well. Possible though. Did you RTV around the coolant passages on the intake gaskets? Even on hard to seal intakes with shaved heads I've never had coolant leak, though have had vacuum leaks.

I'd say head gaskets more likely. Try a compression test it may give some insight, though maybe not. I did head gaskets on a SBF a few weeks ago and compression numbers were good but couldn't explain an overheating problem so figured it was worth a look and had two cyls identical compression right next to each other. One cyl on the opposite bank has blown through to a coolant passage. Compression was good, plug and chamber looked normal, engine ran fine. Must have been minor, but it the gasket had failed. Just a thought. You could put air in the cylinders getting water and see if you can feel/hear air coming through the cooling system.

Still sounds more like cracked or rusted through manifolds and risers, or possibly failed manifold to riser gaskets, given water in all cyls. Another possibility is reversion. Since this is a fresh build what cam are you running? Too much overlap can pull water back into the dry part of manifold and into the cylinders at idle and low RPM unless you've got taller risers, water introduced farther back, etc...

22 hours on the engine, has it had any of these issues previously or just starting now with nothing changed?

[supraaddict]

There are no dumb questions. Just a dumb boat that I'm sick of wrenching on. No, I didn't do anything different with the exhaust. The manifolds are somewhere around 6 years old I'm guessing. The previous owner bought them, so I don't know exactly.

The reason I asked the question is in your OP you stated that you were motoring on the lake just fine and when you shut the engine off it wouldn't restart because the cylinders were full of water. The only time this ever happened to me was when a hose came off for the main water inlet on my engine and my engine temp started rising rapidly, I instantly grabbed the throttle and shut her down. I reattached the hose, let the temp come down to 130 and tried to start her back up. The engine wouldn't crank and same thing... water in the front cylinders. Had the boat towed, got her on the trailer, pulled her out of the water and instantly noticed that the exhaust flaps were melted off. So obviously when the temp started rising and l pulled off the throttle and shut off the key, there were no exhaust flaps to hold back the water and in turn filled the cylinders up with water. Pulled all the plugs cranked her over and over, fogged the cylinders, replaced plugs and wires and she started right up. Compression test good and let her run for about 45 minutes to ensure that the cylinder walls did not rust. Everything seems to be good now (Replaced the Exhaust Flaps as well). Might not be your issue but just trying to give you other possibilities in case something may have changed on your boat.

[TitanTn]

Thanks Brad. Unfortunately I don't have flaps, I have supertrapps, so I don't think this could happen to me. I had been idling for about a minute before I turned it off, so there was no opportunity for water to come back anyway.

I pulled the exhaust manifolds off tonight. I hooked a hose to the water inlet side and turned it on. Water filled the manifold jackets and came out the exhaust side as expected. Nothing leaked back into the exhaust gases side. Did I not test this right? Is it possible that it'll leak badly when it's hot, but not when cold? I'm so disappointed that the issue wasn't obvious. Anyone ever make a tool to remove the riser from the manifold? What now?

[TitanTn]

Based on this article - http://www.boatus.com/seaworthy/swbtob.asp

I think it could still be the manifolds. I don't know how old they are, and I've had the boat for 4 years. Even if they're not completely at fault, I will likely need to change them soon anyway. I think I'm going to bite the bullet and replace the manifolds and risers now. I'll be sick if that doesn't fix it, but I just don't know what else it could be.