I can't see how someone could have ever done the stupendously stupid thing I've just done.

Oil change time. For the life of me I can't figure out why I did this given the number of oil changes I've done on my and my wife's Savages, but just now I turned the oil plug backwards. It had been getting more stuck the last few times I've changed it so I didn't think anything of applying a little leverage to get it started. And then I realized my error when oil started leaking before the plug bolt was out. It never does that.

I started turning it the other way and the plug bolt came out fine. Only after I let the oil drain out did I get to survey the damage: Looks like I cracked the case.

So, that's the season for me. Now I get to spend the winter trying to fix this. What do you guys think I'm looking at here? Replacing the whole crank case? If the crack is small can I use some kind of sealant or is that gonna come back to bite me? I'll post pics in a little while. Can't tell you how stupid I feel right now though.

How long is the crack? Is it on just one side?

One thing is certain, youre gonna need that motor on the bench to either fix it or have it welded.
IF you decide youre willing to go with JB weld, then youve got to find the end of the crack & drill a small hole to give the crack a radius to relieve stress & stop the crack from growing, If you go that way, then before you run a bit in, locate a brass rod just 1/2 a thousandths bigger, run some grooves in it going around, run the plug in to open the crack, press the JB weld into the crack ( that has been Thoroughly cleaned by squirting Berrymans thru it, juice up the brass rod, gently, OHH gently, tap it in,,

Wait,, DRY Run,, Tap that rod in,, pull the plug & make sure the crack closes.. If not, stick the rod in a drill & spin it in sand paper,, play with it till ya get it fitting snug but not holding the crack open,
Then apply the JB weld. Id expect that to work, but the cost of having it welded up coupled with knowing its NOt a JB weld repair wopuld likely be the option Id choose,, Unless I just didnt have the $$$.. I think JB would do it,,Especially if you have a plave you could fashion a plate to go across the crack & JB that on,,

How Thick is the case at that point guys? Its down low,, so maybe they left it kinda heavy, to keep stuff from bustin it,,

Someone had a counterweight go thru some years ago,, Ill bet that allowed for a visual on case thickness,,

Depends on the length of the crack & whether or not the case is heavy enough at a distance from the hole, It may taper from the depth of the threaded hole to a much thinner shell pretty close to the plug.. but thats a good idea if it fits the needed parameters

Here's an imgur gallery of the best photos I could get of the crack. It doesn't look good...
http://imgur.com/a/b5OSq#0

Professional mechanics would say you are in the market for a TIG weld up job.    A good welder man can grind a groove where the crack is and weld it up until it is positive to the old case contours, giving (depending on the weld rod he picks) a stronger case than you had before.   Then he will drill and tap it for a slightly larger bolt.   Warning:  This will be expensive, but it will be full strength durable fix.

A replacement used motor costs $550 (a little more or less depending on the season of the year).   You could pay just about that much to get it TIG welded up and re-machined to be "as good as"..

Taking the engine all the way apart isn't an option, not unless you want to devote a great deal of time doing (and redoing) the engine.  Your costs on a full engine tear down can be as much as a used engine.

Heating stuff up a whole lot in welding can cause damage to the sealant between the case halves, which is a bad thing that will make you have to do a full engine tear down to fix it.


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You might consider this option:   Take the engine off. drain out all the oil.   Spray the crack very clean with Brake Parts Cleaner and heat it with a torch lightly just until the cleaner bubbles out of the crack and clean it again with Brake Parts Cleaner and heat it and clean it  until NOTHING darl is coming up out of the crack.

Then solder the crack closed with some of the propane torch AlumniRod stuff you can buy at Sears or any good aluminum solder material you can buy at the same place.   Your flux has to get the solder to wick down inside the crack all the way or this repair is worthless ....   This level of wicking will fill the threads up too.

Then drill/tap to the same thread, file the mouth flat with a fine file and install an "O" ring or an "X" ring on the bolt head and lightly finger tighten it to seal the oil up inside.   You must use a neoprene or silicone rubber ring to make the seal as NO HEAVY PRESSURE can ever be put on those threads again or they will jack the crack open on you again.

Then check it every week for oil leakage until you get confidence in the fix being long lasting and "oil change proof".

Sorry, but you bit a big one with this particular little boo boo.   Fixing it isn't going to be simple or easy.


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The stock bolt is very long -- the threaded boss might be longer yet.   Get a tap that big and see how far you can tap the existing cracked hole.

See if you can get a quarter inch long section of good uncracked boss, then clean it good and use the hardening SPARK PLUG AND STUD REPAIR lock tite product to fill up the crack.  

You will not be able to use the bolt to install the locktite as per the stud instructions.  PAY ATTENTION -- NO BOLT.   You will push the Locktite paste into the crack with a piece of wood or a small flat blade screw driver, pushing it all the way deep into the crack.     Wipe off the excess paste until you can see threads again, you will need those threads to start your tap when you cut the new threads.

LET THE LOCKTITE HARDEN COMPLETELY.

Now re-tap the hole cleanly and see if it will support a tight fitted on the bolt rubber "O" or "X" ring at practically no tightening stress without leaking oil on you.

The lock tite method requires no heating which could destroy the case sealant between the cases and result in an engine tear down for oil leakage.   That is the only advantage to this method.

Another (possibly dumb) question: it appears like the threads inside the hole are part of a sleeve of some kind. Would it be possible to replace this sleeve or am I seeing this incorrectly?

Thanks for your continued explanations. I like the sound of the locktite method—for exactly the reason you've highlighted. I think I get what you're saying but I'm a bit confused about tapping the cracked hole. What am I doing with that step?

Everything from there on in makes sense, but let me parrot it back to make sure I've got it:

Clean it exhaustively until it's perfect. Then fill the cracks and threads with locktite and fit it with a 17mm bolt (but not my plug) to fill the hole and then drill it and tap it again, then fit my plug with a silicone x-ring and gingerly tighten the plug from now on (avoiding any pressure that could crack it open again).

The "oil drain valve" idea is a great one. I used to have an MG, and there was an aftermarket, screw-in little spigot available that seemed to sell well...Someone with appropriate skills and equipment should create and market one for our singles (they were about $20, as I recall).