This looks Serious

[LastLeg]

Finally spent the entire summary rebuilding engine in dry dock.

Great compression on all four, new carb and mew exhaust manifold.
New head two head gaskets.

The engine started on first crank and I let it run for about 30 minutes to check temperature all is good. the next day I found the cylinders filled with water???? Worked out the water thought that perhaps it syphoned from my water supply bucket for the engine cooling. Was able to start again, the engine purred without a missed beat, it never had run so well.

Shut if off and the cylinders filled again with water!!!! This seems pretty serious I do not know enough about this engine to understand why this is happening. I am ready to take out the chainsaw

[CalebD]

I think you are supposed to change the oil a few times once water gets inside.

You are cooling the engine with an external bucket of water. The water is obviously continuing to siphon into the engine when the engine is off.
Remove the cooling water hose from the bucket when you shut down the engine.

[LastLeg]

The second time I let the engine syphon all of the water from bucket and still had water in engine cylinders.

[LastLeg]

I originally thought that maybe when I removed the hose it siphoned back in, I started the engine again, and let it run for 30 minutes, no issues as soon as I shut this motor off it the cylinders filled up with water again. If I remove one plug at a time I can blow the water out and it will start but have no idea what is happening. As soon as I shut the engine off I pushed the hose back into the engine compartment so it was below the engine.

Maybe the water is flowing back from the muffler??? Or can the brand new exhaust manifold have issues?

[LastLeg]

I am about to display may ignorance on this site amongst some pretty smart people. Please have a look at how I refitted the manifold, could this be the reason why water is going back into my cylinders???

Should I have a 90 degree upward angle after the exit in order to bring the pipe above the manifold black bypass hose?

[tenders]

I think the liquid side of the manifold has to join the exhaust gases past the "point of no return" - an area in the exhaust which runs downhill.if I understand what you've shown us, your hot coolant has to be pushed uphill by the exhaust gases before exiting the boat. What isn't pushed uphill when the engine is shut off hasnt exited the boat yet, wont do it by gravity, and is going to drain back into the cylinders.

[ILikeRust]

Your setup absolutely will result in water running back into the engine.

The "hot section" of your exhaust (i.e., the part before the water is injected) needs to go up vertically and make a "U" and then head down, so that the water is injected on the downhill side, far enough that it cannot run back into the engine.

Edit: wait a minute - is that a jacketed exhaust pipe? If so, ignore my previous comment...

[CalebD]

I believe that tenders is correct about where the mixing elbow is supposed to be: on the downward slope side of the exhaust, before the muffler.

[LastLeg]

Yes it is a jacketed exhaust pipe, but does not water run through the hot section as well?

[hanleyclifford]

Originally Posted by LastLeg

Yes it is a jacketed exhaust pipe, but does not water run through the hot section as well?

It is indeed a jacketed system and if it is tight the installation should be OK. But if water is getting into the engine there is a breach inside that you cannot see. The jacketed pipe will have to be tested.

[hanleyclifford]

Looking at your picture it appears that the most likely spot for the leak is where that steel pipe joins the internal pipe in the jacket. This will not be visible until you disconnect the two pieces. A quick test would be to pressurize the water jacket and see where the water escapes. There should be no water in that hot section.

[ILikeRust]

Originally Posted by LastLeg

Yes it is a jacketed exhaust pipe, but does not water run through the hot section as well?

Not unless something is leaking.

[Mo]

IMHO what I see in the pic has to let water back into the engine. I don't see how it can't. Not my intent to cut up your efforts.

[ILikeRust]

Mo - if it's a jacketed exhaust, and the jacket isn't leaking, the water shouldn't get back into the engine, no?

[Whippet]

Attached is generic exhaust design from Moyer. Common element is that water exhaust has to loop above waterline.

Generic exhaust lay-out.pdf

[ndutton]

LastLeg,

Can you please provide details of the rest of the exhaust system, pictures or drawings? It's of critical importance what is happening beyond the picture in terms of relative elevations to be able to offer a decent analysis.

[joe_db]

IMHO the jacket has a leak and is flooding the engine when you turn it off.

[BunnyPlanet169]

A new jacketed exhaust will not let water into the hot section till very near the end, where there will be a 'necking down' with a smaller tube from the jacket injecting to the hot section, and then typically a wet rubber exhaust hose for vibration and alignment to the thru hull (above the waterline.)

An older jacketed exhaust may very well have a leak between the hot inner pipe and the outer jacket. Depending on the geometry of the exhaust and location of the leak that could lead to a reverse siphon.

Mine leaks as evidenced by exhaust gasses in the hull if I forget to put the jacket drain plug back in during Spring commisioning. It's properly located on the underside of the jacket at the lowest point - and invisible as a result.

I looks from the picture that the exhaust makes a run straight uphill after the second bend (by the sneaker). There will always be standing water at the elbow, and opportunity for corrosion depending on how the pipe was fabricated.

Copper is very durable in salt water. But there are brazing joints visible in the picture, and perhaps on the inner hot section as well. Also, as Hanley has pointed out, the steel pipe joins there somehow too. These joints will become problematic where there is standing water.

[ILikeRust]

Originally Posted by Whippet

Attached is generic exhaust design from Moyer. Common element is that water exhaust has to loop above waterline.

Attachment 8179

Note that that is for a system using a wet-lift muffler. It appears what we've got here is a jacketed pipe.

As Neil says, we need to see the whole system layout to know what's really going on.

[LastLeg]

I am anxious to get back to the boat this afternoon to respond to this thread, I very much appreciate your help here. It is a jacketed muffler and I pressure tested it with a garden hose prior to reinstalling, I will send more pictures but first I plan to disconnect the hot section and run the engine for 5 minutes to see if water is coming out of the hot exhaust section. Also keeping the water line hooked up I can see if water comes back out the pipe into the bildge when I shut down the engine.

[ndutton]

Good test but be VERY careful. Those exhaust fumes are deadly.

[dvd]

He says that on his second try that he completely emptied the 5 gallon bucket. It appears that his exhaust set up can allow water to back into the engine but can it do that while the engine is running???

Maybe there are some other issues. Hopefully not.

dvd

[BunnyPlanet169]

As Neil suggested, a sketch with relative elevations would be extremely useful.

Pressure tested with hose - can you describe that in more detail? I would be very careful putting full 'city' pressure (40PSI on my well) into an older copper jacket - it would certainly plump out any dents!

There may be a similar fitting to what's in your picture at the other end of the exhaust, where water exits the jacket, and is injected into the hot section. A hose test would be to plug one end and see if you can or can't push water into the jacket.

This test will also fill the cylinders if there is a leak between jacket and hot sections. I'd disconnect the union first...

Mine is hard plumbed at the back end - a soldered copper goose neck tube from jacket to hot - I wouldn't be able to perform this test on my system.

[hanleyclifford]

As I continue to study that picture it seems there is a weakness in the design that suggests a leak. The hot pipe from the union has to be threaded into a connection with the inner pipe carrying the exhaust. That connection must be somehow suspended on a plate that blocks the end (of the jacket)and connects to the outer pipe carrying the water. Even a little too much tightening of that hot threaded pipe into that connection has the potential to apply shear to the internal soldered connection. No provision can be made for "holding" the inner pipe against the torque being applied on the threaded piece outside the unit.

[LastLeg]

I disconnected the muffler and kept the water bypass hose connected dried out the cylinders and started her up and noticed that considerable volume (about 85 to 90%) passing through the muffler jacket out the back of the boat, no water reversed out the hot side pipe that was connected to the muffler. I did notice about 15 % water spraying out of the exhaust coming out of the exhaust man. It appeared as the thermostat openned (with the hotter engine) the volume coming directly out of the exhaust increased a bit.

I shut of the engine after the 3rd test about 3 buckets (15 gallons) I was unable to restart the engine because of water back in the cylinders, so I assume this eliminates the muffler unfortunately.

this is a poor video because of the fumes I was unable to hang in the engine compartment. http://www.youtube.com/watch?v=UnzWZ73yYy4