Removing galled alumunm

The last time I did this repair, I used my Swiss army knife carefully.
Wes

Heavy emphasis on 'carefully'?? I'm looking for the magic bullet!!
Actually, I was really pleased that the engine looks rebuildable.
Wes wrote:

Lye will do it. Much easier/faster if you can immerse it. Drop-by-drop would be tedious. The journal will not be affected, other than a very good degreasing.
Bob

A brass wire wheel, NOT brass plated wire. Check it with a magnet.

Lye is good, but not a few drops. You'll need to cover it with solution.
If your patience is slim and if you want to do it at room temperature (a safe idea), you can use some Pequa drain cleaner. That's a straight 45% lye solution in water, and it's so concentrated that it's actually slightly viscous. 45% is dangerous to handle but it does the job. Dilute 50% with water if you're edgy about using a concentrated solution.
I've used 20% with success -- in fact, I've wrecked a few aluminum parts with it, trying to frost them. d8-) For reference, a 40% solution is 1 kg of lye to 1.5 liters (1.5 kg) of water. That 1 to 1-1/2 ratio is easy to remember.
My lye tank for small parts is a plastic Tide bottle cut in half. Don't use it with hot lye.
-- Ed Huntress

CLR (calcium, lime, rust remover) works too. Paul

Take it to an automotive machine shop with a boil out tank. they will charge you a couple bucks at most. Aluminum will be gone as well as all crud.

It contains some mild organic acids. They probably will have no harmful effect over a short time, but I wonder how long you can leave a steel crankshaft in them. Any idea?
-- Ed Huntress

If there isn't a hole in the case, you got a good chance. I've fixed a few law mowers when I was a kid.
That lye thing is looking good from the responses. Wash crank then clean and oil after the lye bath.
Just out of curiosity, what is the engine mounted in?
Wes

This is the 12 hp Kohler K301 that is all cast iron. The output shaft bearing is a standard ball bearing with a 1.574" ID and around 4" OD. I've never seen such a massive bearing on a small engine. The flywheel end is the same 7/8" that most similar engines use for the drive end. It took two of us using a chain and sling to move if from the garage to the shop, feels like it weighs around 100 pounds.
Everything looks good inside except for a chip taken out of the lower cylinder, perhaps 3/4" square.
My local supplier has a piston, rings, and rod package for about $70. I'll check for taper and all that, good chance I'll bore it oversize. It's about due after all those years!
The engine was in a '64 Cub Cadet tractor that I've had since the '70's. About every 10 to 15 years I hone the bore and put new rings in. That little chore was scheduled for this fall, had one more 1/2 hour session before layup. Blew on startup.
The cylinder fins were completely caked in dust, no air flow what so ever. Suspect is was running way hot, burned the oil, finally grabbed the rod bearing .
Wes wrote:

I have a couple of hot tanks that I use for stripping paint with strong alkaline. The small one is for heat registers, would fit the crank perfectly. I normally run these at 160 degrees, I suppose that would be a bit of overkill.
Paul wrote:

It should speed things up. It sounds like you're all set.
-- Ed Huntress

How do you plan to bore it? Lathe, mill or send it out?
Wes

Bridgeport with the vertical extension block. Standard boring head. Bottom of the block is flat, 12" high, 6" cylinder length. Not enough travel on the spindle, would need to use the knee. Mount the block on a tooling plate, clamp that down. Use a cylinder hone to get the surface finish I need.
I checked the bore this afternoon, about .001" taper, about .001" oversize. Looks like a stock piston would just go in.
Wes wrote:

I hope your luck is better than mine.
I've tried this more than once with old Kohlers and not had much luck.
First one I did it right. I had it bored and the crank ground. I replaced every wear part (with Kohler brand not after market). Full rebuild. I ran it one month when it threw the counter balance gear through the side of the block. Moral of this lesson check the wear on the timing gear. Unfortunately it's made on the crankshaft and can't be replaced without a full crank (be sure your sitting when they qoute you the price). If you have some wear on the gear and have the counter balance gears my recommendation is to leave them out. It vibrates more but if the gear happens to get on top of the tooth and snaps the shaft like mine then it's not pretty.
I tried at least three other times after getting several of the same engines in a trade. None lasted more than a year or two (though I admit to cutting more corners on the later ones) . The last had the chip you talk about out of it and it ran about 1 1/2 years before the oil burning got bad enough I had to give it up.
I finally broke down and put a new 16HP Kohler on my old John Deere mower. It's been running great for 10 years now (though I've noticed it's been a little harder to start lately). That was another adventure since John Deere didn't use a standard Kohler engine but rather had a special oil pan to drop the engine lower over the front axle and had a smaller out put shaft than normal. The special engine was $1600 when the standard 16HP I replaced it with as $700.
Just a heads up of potential problems.

Not in my experience.. If it does it's awfiull slow

Ed, I've soaked HSS taps in CLR for upto a week to remove aluminum stuck in the teeth. The surface of the steel turns black but the cutting edges are still sharp. Paul

Hmm. That black oxide may be a problem on a crankshaft. At the very least it would have to be removed.
Have you ever tried using a lye solution? It eats aluminum pretty fast and it doesn't hurt the steel.
Warm, 40% lye solution will actually bubble hydrogen gas off fairly violently as it eats the aluminum. But you don't need a 40% solution to do the job on cutting tools. A couple of tablespoons of lye in a cup of room-temp water will do it.
-- Ed Huntress

And lye would do the same in about 5 minutes. It won'e embrittle the taps either.