Just tore down my old engine to rebuild it and found the source of the coolant issues (coolant consumption, and overflow) looks like the cold side of the o ring groove failed into the water jacket on the front side housing. This allowed the o ring to bulge into the water jacket. The front rotor housing had quite a bit of carbon buildup as well. The engine always ran great, but was consuming coolant. I was expecting a toasted o ring failure, is this groove collapse a common problem? there was only about 1/8" of iron under and outside the o-ring groove which seems a little on the thin side to me. In any case I'll be needing 2 rotor housings and a front side housing to do the rebuild- if anyone has very good or new ones at a reasonable price please let me know
tom

 

Tom,

Did you try the block-weld trick on this motor? I'm wonder if would have worked?

 

I have seen it before. Guitarjunkie even has a write up on how to repair it, on here some were.

 

I did blockweld it, and it worked for a while including a few track days, but then got worse. I'm surprised the engine ran with that 3/4" long piece missing. I suppose I could get someone to tig weld it but it would be a little tricky to re machine that curved groove back in there. probably be cheaper to get a new housing.
t

 

I had something close to that happen to me. I was shocked how brittle the o-rings were after being fried.