Hydmech,
If the housing is cast steel, it can be welded using E7018 electrodes. I would drill a small hole at each end of the crack before welding or brazing to prevent further cracking.
The housing might be cast iron, the way that I identify cast iron from cast steel is the size of the fillets on the casting, cast steel has smaller fillets and sharper corners.
Drilling cast steel produces a normal continuous chip and cast iron produces powdery chips.
If it is cast iron, brazing would be your best choice, grind out the crack for full penetration.
Larry