1951 pan engine case leak

[sla0001]

First off the engine is assembled,out of the frame,and the mount areas have been repaired,i purchased it this way and they had been done profesionaly,although the welds showed,machining had been performed to true the mounting sufaces up.
Ive never run the engine,i had almost completed the bike last october and was putting a little oil{tablespoon} in the cylinders to store,and then kicked it a couple of times,next thing i know{about 20 min} it had leaked from the rear mount area,i pulled the engine and sure enough it had leaked from the corner{90 degree}at the front of the rear mount.
any way i can seal this without pulling it apart?
Anything will be much appreciated.
Thanks in advance...

[Panacea]

Sla, I'm no expert, but a small amount of oil inside the cylinders shouldn't leak out by the rear motormount. Maybe it's the base gasket. If you kicked a while the oil could have circulated up to the top end, then returned down the passage in the cylinder to the top of the case where it may have gotten by the base gasket. Otherwise, if you do have a crack, then yes you will have to get that welded up. Sealers in my opinion are a waste of time. Good luck, Mike

[sla0001]

Thanks for the advice Mike...i wish it were the base gasket,it would not be so much trouble.it must be a crack,i thought someone might know what it would be before i jumped into it.
ive worked on this bike off and on for 8 years and something always comes up to keep me from finishing it every year.
Also Can you or anyone else tell me the best sealer for the cases currently out there?
Thanks again,Scott

[Cotten]

A few pounds of air upon the timing hole and some soapy water will show exactly where the problem is.

The rear motormount boss houses a chamber for draining the "windage" oil peeled off of the flywheels by the case scraper. Hydraulic pressures when the motor is spun through causes the seam between cases to be leak-prone.

It happens to the best of us.
I succeeded in sealing a fresh '49 by carefully scraping the seam with a dental pick, and filling it with my favorite isocyanate paint.

As far as a favorite sealer to start with, I prefer 3M Industrial Adhesive #800, which carried a -81 OEM number from the Factory.

(Yamabond 4 proved to have a limited lifespan)
.....Cotten

[Pantony]

My best sealer for case cracks is aluminium; and a tig welder

[sla0001]

Thanks to all of you for the help...i could not get a hold of the 3m sealer,but i made due and i hope it stays sealed,
welding was the last resort,but i agree nonetheless.
Scott