Backing up, wave & water forced back thru exhaust?

[customfab]

Wondering if anyone has had a negative experience in getting water flushed back up into the exhaust and partially into the exhaust manifolds?

I ran into this situation last weekend I believe. I was picking up a passenger from the shore. He jumped into the bow of the boat and I gunned it backwards at full speed to avoid shore rash on hull. Unfortunately, a large wave from a 30 foot+ boat was behind the boat and we nailed it. Water capsized over the entire rear end of the boat, soaking all the passengers sitting on the back seats. Later I found water in the exhaust manifolds and believe the root cause is the wave from a massive pressure surge which forced water past the flapped and up through the exhuast.

Any thoughts or experiences with this?

[zad0030]

First I must scold your driving I dont see why you were coming in that fast that you need to gun it in reverse.

I may be wrong but I believe water should be in the exhaust manifold, or at least some parts, because thats where all the cooling water exits.

Then the flaps are there to prevent back pressure when in reverse. The water pressure forces those closed and I dont see how a wave would affect the function of the flaps. And then I dont see any water getting very far if it did get in there with the pressure of the exhaust pushing it out.

Has it been running fine since then?

[Timmy!]

Yep, you're supposed to have water in the exhaust manifolds - they even have a drain plug on them for winterization.

[Joeprunc]

I think the OP was not infact referring to the exhaust but to the rear vents. Most boats have vents in the rear above the bumper rail. I believe these vents are for the blower (purging the exhaust fumes from your engine bay). If you have water in there it will not effect your boat...but I would try to get it out, or dry it out before it causes any mold/musty/mildew odors.

[brett22i]

You can push water back through the manifold into the engine. Ofcourse if you did do that your engine wouldnt run? Hopefully you didnt do that.....

[customfab]

Alright I deserve some criticism but the mechanical side of you is lacking!

I actually wasn't driving. It was my buddy but I wanted to keep the story simple. And yes, he was a dumbass for backing up with such speed and he shall be punished!

In terms of the manifold, there are water passages but they are separate from the exhaust passages. The water passages allow the water which cools the motor to exit out the back of the exhaust. However, the exhaust manifold keeps the water passages isolated from the exhaust gases until it exits the outlets of the exhaust manifold. You should never have water within the main exhaust chamber as it risks the motor as a whole. The water can work past the exhaust valves and into the cylinders........water is incompressible.....result is typically be a bent rod.


So I was curious to see if anyone had literally experienced this happening. You see, I had a compounding problem that could have also caused the water. My serpentine belt was already loose and the water incident caused the belt to slip entirely. Resulting in no impeller being driven off the pump....so motor got hot and set off the warning alarm. I then took off the manifolds, did a leak down test and compression test. I couldn't find a blown heat gasket, cracked manifold (intake or exhaust) which might explain water in the valve area and exhaust manifold. Since I could identify a root cause, I’m theorizing that the water was forced back into the motor due to the incident......not likely but possible. Trying to find confirmation of this event……makes me feel better or I’ll continue to worry that I’ve got a cracked manifold or blown gaskets.

Just to let you know. Compression was an even 170-175psi across all 8 cylinders. I replaced all riser and manifold gaskets. Ran the motor for an hour last weekend and the boat appears perfect.

You can push water back through the manifold into the engine. Ofcourse if you did do that your engine wouldnt run? Hopefully you didnt do that.....

[da.bell]

Have you check to see if there is water in the oil???

If it's chocolate milk color, you have a problem.

[zad0030]

Maybe due to the fact the flaps were closed, tightly enough, that no exhaust got out and the pressure built up inside the manifolds.

Idk...

[customfab]

Very nice idea. Another explanation. I did only experience water on one side but the pressure built up could have been uneven.

YES on oil check. No milk! No water whatsoever which says no significant amount of water was build-up or allowed to creep past the rings.

Maybe due to the fact the flaps were closed, tightly enough, that no exhaust got out and the pressure built up inside the manifolds.

Idk...

[da.bell]

Sounds like you might be okay.