18hp h2o in bottom cylinder

[johnyrude200]

I have an early 60’s 18hp that has water in the bottom cylinder. I’ve already changed the head gasket, pulled the exhaust bypass to look for pin holes in the SS baffle, and checked the crank carbon seal and see no evidence of leakage in any of these areas. I replaced both gaskets on the exhaust bypass SS plate. Also checked the cylinder head for warping along with the powerhead but can’t find any evidence of being off to the point where the head gasket wouldn’t create a good seal.

Were else could water be getting in from? I’ll check the bottom cylinder for hairline cracks around the water jacket but that would be a first.

[frankr]

Is it possible that somebody turned it upside down after the last time it ran?

[amuller]

Is this a recurring problem?

[johnyrude200]

Still doing some investigation. I pulled the exhaust bypass a 2nd time (drilled 2 holes in the lower cowel so I could get at the 2 lower screws without pulling the powerhead a 2nd time) and also pulled the cylinder head. I used a drill gun to turn the motor over at a reasonably high speed (whatever the drill gun would turn…I would assume around 200-300RPM).

Observed water flow up through the bottom of the powerhead, the usual spots. Replaced the exhaust bypass plate and repeated, did not see water getting into the cylinders. Replaced the cylinder head and repeated, did not see water getting into the lower cylinder.

It does appear that the bottom cylinder is very wet with fuel mix, so I’m going to pull the carb a 2nd time and take a closer look at the manifold. I guess maybe a leaf plate is distorted and it might be flooding badly? Will report back shortly. The top cylinder is burning as it should, bottom is soaked when I pulled the plugs (as in, plug was very saturated and wet).

Yes it’s been recurring, only started on working on this motor yesterday and it has a 100% fresh ignition system (nice 1/2 spark both cylinders), and I went through the carb, so now I’m moving onto other aspects. At this point there isn’t much left on the motor that I haven’t touched yet. I don’t think the fuel pump is leaking fuel through the diaphragm because it sits on the top cylinder (separate fuel filter setup type pump), and the bottom cylinder is the one that is soaked/wet/not working right.

While running the motor it’s a hard start, even when timing is advanced to the highest neutral setting (not WOT). Once started if I shift to forward quickly, I can get to WOT, but it sounds like it’s intermittently picking up the bottom cylinder and only running off the top cylinder. It clearly does NOT have the power that it should.

I’ve already switched plugs out with a new set to rule out a bad plug.

[frankr]

In other words, the H2O in the bottom cylinder may actually be fuel and not water?

[fleetwin]

yeah, doesn’t seem like you are 100 percent sure just what liquid is flooding the bottom cylinder. You could simply remove the gearcase then start the engine for a few minutes to see if it runs any differently….If the bottom cylinder is still flooded, then it must be fuel….
What cylinder is the fuel pump plumbed into? Perhaps the diaphragm is leaking if it is plumbed to the lower cylinder. You could pull the fuel hose and let the engine run to see if it cleans up once fuel is out of the pump…Perhaps this test should be done before going through the trouble of removing the gearcase….
You have had the head and exhaust cover off, so it would seem like you would have seen any obvious internal problems, perhaps you have a bad leaf plate/reed to the lower cylinder.

[johnyrude200]

I’m beginning to suspect that Frank, perhaps the first time I pulled the cylinder head, some water leaked into it during removal and gave me a false positive.

It was/is behaving like a motor with water in the cylinder, but of course with the motors which do have the water leakage issues, it’s usually in both cylinders, so I am investigating further. When I ran the motor with the head off using the drill gun, I did so for several minutes, stopping every 30 seconds or so to wipe down the bottom cylinder of fuel mix (the carb still had fuel in it from when I shut it down.

Once I got it to the point where I didn’t see signficant accumulation, I put the cylinder head back on and ran it with the drill gun. Pulled the head and didn’t see any water in the bottom cylinder, but just some more fuel mix. Top cylinder has remained "dry" throughout this whole process. The motor has been in the barrel and pumps water whenever I use the drill gun so I know water flow is occurring as it should.

Trying to figure out how just the bottom cylinder would be loading up. Either there’s some sort of ignition issue on cylinder 2 I’m missing, or it’s a fuel issue. More investigating to follow…

[johnyrude200]

Don I agree! Going to check the leaf plates next on the manifold. This motor will have been taken apart nearly 100% by the time I’m done (less the crank case, rods, and pistons!).

Will report back with results.

[johnyrude200]

Found my smoking gun. Give me a few minutes to get a good picture. This situation will be a new one for me!

[johnyrude200]

Well, at least the motor has a lot of new stuff on it that it didn’t need now.

Good thing leaf plates are made of brass. No signs of the broken fin anywhere and the motor shows even compression at 120/120.

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