While it's not certain to say 100%, just from looking at a couple of photos, that doesn't look to me to be terminal in any way. However, while the motor is apart, it wouldn't hurt to pop the casing to a local engineering firm and have them inspect it and give a professional opinion. They may well say that running a bead over it is a bit overkill.
To me it looks like maybe a bit of contamination in the casting, that's just "flaked" a little near the surface. It's a non-structural part of the casing, and the torque values for screws in that area are very low. I'd be extremely surprised if it failed catastrophically or too quickly to not notice and kill the motor before any damage was done through loss of coolant. That crack would need to run very deep for it to be a serious concern really, IMHO.
Again, very hard to be entirely sure just from photos, but it's probably fine.
I'd say it's similar to the other side, just a bit more pronounced!
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Andy.
NSR-WORLD.COM
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