Ariel #414

[414]

Here is a view of the inside of the exhaust elbow and the exhaust port on the head. The port on the head was about 2/3 full but I couldn't help but poke it before getting a picture. Obviously the head is coming off so we'll see how she looks on the inside.

On another note - I'm pulling the current fuel tank and building a new one. Any input on size that would make sense? From research it looks as though 3 gallons will get about 12 hours of run time so I'm thinking between a 3 and 4 gallon tank but I'd be open to input before I go building one. It will be a custom tank - not interested in a portable or plastic tank - I'll just make it up from either stainless, aluminum or (dare I say it?!) mild steel! or I might cut up the current tank and reuse it's bits and pieces. It's aluminum. The reason to move to a new tank are many including:
-Tank is under cockpit floor and the filler is in the cockpit floor too.
-Tank is too big and it will take too long to move 12 gallons of diesel through this little bugger.
-Tank has no access port for cleaning. New tank will include a port large enough to get a hand inside

Another question I have on the tank is where is the best place to mount it? I'm thinking about inside the rear lazarette with the fill neck in there too. I'd need to open the hatch to fill it but it would limit the potential for water entry and would be nice and tidy looking. Spills while filling could be an issue with other items in there but I need to be careful either way (don't want diesel going overboard through the cockpit drains either). Breather would be kept in the same location on the transom.

Thanks for any input!

-Ben

[Bisquit]

Good luck with the rebuild. Looks like she needs it but I think the 2GM is worth the effort. I have a 2GM and I put my tank on a shelf under the cockpit floor above the stuffing box. The fill is on the cockpit floor but no problems with water or spills so far.

[414]

Hi Bisquit,

Thanks for the response - I know it's a common place for the tank and would probably be fine but it just gives me the hebejebes! What has your experience been with with fuel consumption? Ever have issues with algae in the tank?

Pulled the head off late last night and everything looks good. Cylinder liners are in great shape with cross hatch still visible and no scoring or uneven wear apparent. Valves looked good too. A little carbon build up on everything but nothing that would cause the engine to not run or even run rough. I lapped the valves since I had it apart anyway and cleaned all the carbon that was accessible. Going to order the gaskets and get it back together soon.

The thing I was not expecting was the water injection elbow (it's the u-shaped one in this case). On the outlet side it was very corroded but had a fair amount of area for gasses and water to escape as you can see in the picture. After much heating with the oxy-propane rosebud the inlet side came apart (meaning separated from the exhaust piping that is between the water injection elbow and the cylinder head, what would be called the manifold if it had multiple ports) the interior had closed down to less than a pencil's width for the exhaust to escape! It was impossible to see this until the two had been separated. In the photo you can see a greenish area that is the passage.

So my thoughts now, after seeing the inside of the engine looking quite normal, is that the exhaust had closed down to the point where back pressure was extremely high and thus the engine could not pull in the fresh air charge. This made the fuel to air ratio very rich for any given engine load and caused incomplete combustion, giving the black smoke that Mike experienced back when she conked out. The only thing this doesn't explain is why the mechanic reported low compression on inspection in the boat. I should have tested it before tearing the engine down but I was just so convinced I'd find a smoking gun in the valve train or scored up cylinder liners I just went for it - lesson learned.