MG Car Repair: Crack in bell housing in 74 Midget, differential question, jb weld

Question
Hi Howard,
Thanks for the quick response to my differential question, I really appreciate that.  I have another issue.  While separating the gearbox from the engine, I noted a crack in the bell housing.  It starts on the upper edge, about an inch and a half away from the upper mounting stud.  It is about two or three inches long and is mainly on the lip.  Can I take it to a welding shop and have it welded?  Is this something that I could use metal epoxy (JB Weld)?  Is it even something to worry about?  

Answer
Hi Corey,
The bell housing is under a lot of strain and vibration so epoxy is not an option. A good aluminum welder may be able to weld up the crack but then you would need to examine the weld at times to see that the crack did not start again.

I have pulled a reinstalled many Midget engines and transmissions and I have only seen one cracked bell housing and that was obvious why it was cracked. An inexperienced mechanic either tried to tighten one point to get it to mate up to the engine or they removed all but one bolt and tried to pry the bell housing from the engine.

Yours may have been done that way and they just ignored it. If it were mine I would have it welded up on the outside while bolted to the engine to keep the flange square to the block. Then unbolt it from the engine and have it welded inside also.

It is not that your engine produces that much torque but it is the strain and vibration that will make a crack get larger until it causes a problem.

Howard