Water in 8 plugs and manifolds

[wakeup 19]

3 year old mercruiser manifolds and risers, 30 dancer raw water cooled. I run in salt stored in brackish. Winterized properly by draining water and filling pink anti.
Ran at idle all spring finally got to go out last Saturday and got on plane for about 30 seconds Engines starts bucking and losing power. Get on plane again same issue. Hydrolocked engine. Pulled plugs plugs all wet. (Put oil down cylinders after getting water out)
No water in oil. Checked under t stat for hole in intake looks solid. Pulled risers water in both manifolds exhaust section.
My buddy who is mercruiser mechanic but has no time says his engine backfired in sucked in water. Bad coil. Checked my wires last eve coil wire definitely loose. Wanted to get manifolds pressure tested can’t find any one who does it locally.
Any thoughts

 

[scoflaw]

Instead of pressure you could fill with acetone, it's thinner than water. If they check out, I would take a close look at the intake manifold

 

[Big Island Lifer]

What condition are your exhaust flappers in? I flooded my engine coming off plane when the flappers were worn out. Just something else to think about.

 

[wakeup 19]

What condition are your exhaust flappers in? I flooded my engine coming off plane when the flappers were worn out. Just something else to think about.

No flappers had too many issues. Didn’t slow down to fast for water ingestion. Problem happened getting on plane first time

 

[wakeup 19]

Instead of pressure you could fill with acetone, it's thinner than water. If they check out, I would take a close look at the intake manifold

How exactly is this performed? Thanks.

 

[wakeup 19]

How exactly is this performed? Thanks.

What is Best way to clean while out of boat

 

[scoflaw]

Plug the bottom feed hole and fill the water jacket up to the top where the elbow would mount. Let it sit overnight and see if the level drops

 

[PlayDate]

I don't think you have an exhaust manifold problem.

Taken at face value you said all 8 plugs were wet and there was water in all 8 cylinders. Water on one side of the engine or the other would make me suspect the exhaust but you need something that is common to both sides of the engine to soak 8 plugs. If the intake manifold is 27 years old, I would probably start there. Checking under the t stat won't show a crack into the plenum. A intake crack into the crankcase would have turned the oil into mud. If the intake manifold cracked between the water passage and the plenum due to age/ice, it would fit the problem.

Your busy Mercruiser friend is just keeping you busy checking things. A single backfire won't cause all 8 cylinders to load up on water. Repeated backfires are not good but a single one won't hurt a thing that wasn't already compromised. For example....if the intake manifold has a crack or is rusted and close to failure....a backfire can cause the failure to occur.

 

[wakeup 19]

I don't think you have an exhaust manifold problem.

Taken at face value you said all 8 plugs were wet and there was water in all 8 cylinders. Water on one side of the engine or the other would make me suspect the exhaust but you need something that is common to both sides of the engine to soak 8 plugs. If the intake manifold is 27 years old, I would probably start there. Checking under the t stat won't show a crack into the plenum. A intake crack into the crankcase would have turned the oil into mud. If the intake manifold cracked between the water passage and the plenum due to age/ice, it would fit the problem.

Your busy Mercruiser friend is just keeping you busy checking things. A single backfire won't cause all 8 cylinders to load up on water. Repeated backfires are not good but a single one won't hurt a thing that wasn't already compromised. For example....if the intake manifold has a crack or is rusted and close to failure....a backfire can cause the failure to occur.

Thank you for response. The intake is not original, not sure of exact age. When I replaced engine last year probably should have looked for replacement but difficult to find. Saw some “new” ones on eBay from China they are cast iron. Not sure I trust their product. I am in agreement that issue is not manifolds. Never seen plenum in these go but makes sense with all 8 wet and crankcase no water. Will it be easy to see when I have it remove it.
Going to do compression check tonight as well

 

[wakeup 19]

T

Plug the bottom feed hole and fill the water jacket up to the top where the elbow would mount. Let it sit overnight and see if the level drops

Thanks, will give it a try

 

[scoflaw]

Pressure test the entire water system before you take the intake off. Simple to do. Block the 2 lines that go to the manifolds and the feed line from the raw water pump. Take out the 2 threaded senders and put a gauge and shrader valve in those 2 holes. All this happens at the t-stat housing

 

[wakeup 19]

Pressure test the entire water system before you take the intake off. Simple to do. Block the 2 lines that go to the manifolds and the feed line from the raw water pump. Take out the 2 threaded senders and put a gauge and shrader valve in those 2 holes. All this happens at the t-stat housing

Scoflaw you lost me. I am fairly technical but far from mechanic. I don’t have threaded senders - shaders. It’s only easy if you know how to do it.. I wish I did. Going to do compression test tonight to make sure nothing internal is wrong when I hydrolocked. I agree with play dates reply probably not exhaust,

 

[douglee25]

The above suggestion could be possible. One other possibility is if the manifolds were 'thought' to be drained correctly, however, the drains were never rodded out and they were plugged, they likely could have both cracked and led to ingestion.

 

[scoflaw]

Scoflaw you lost me. I am fairly technical but far from mechanic. I don’t have threaded senders - shaders. It’s only easy if you know how to do it.. I wish I did. Going to do compression test tonight to make sure nothing internal is wrong when I hydrolocked. I agree with play dates reply probably not exhaust,

Take a look at your t-stat housing, You have two npt threaded senders there.

 

[wakeup 19]

The above suggestion could be possible. One other possibility is if the manifolds were 'thought' to be drained correctly, however, the drains were never rodded out and they were plugged, they likely could have both cracked and led to ingestion.

I thought that too but I remember using 6 gallons of pink. 2 fr each engine and 1 for each manifold. I do it the old way of draining and filling manually. Ran for 2 hours at dock. Understand no pressure. Anything is possible

 

[wakeup 19]

Just to follow up on issue w wet plugs and exhaust manifolds. When the coil wire loosened it caused engine to die and water to enter thru exhaust. Removed and double checked risers intake and gaskets all solid. Cleaned up after oiling all cylinders and installed flappers. All good this weekend. Thanks for all the help.

 

[PlayDate]

Good work! I'm glad it was something that didn't cause any permanent damage.