Russell Duffy wrote:

About 435 hours since I originally overhauled it (straight from the junkyard). 30 seconds after the first run (no oil) I took it apart and put in new bearings. Then ran about 245 hours before my first blow-by got annoying (not as bad as the last), replaced O-rings with stock. Then ran about 180 hours through this overhaul.

 

Thanks for the history.  Do you figure these housing were bad from the beginning, or why to you think you're having these problems?  

 

Cheers,

Rusty (I'm buying a plasma cutter)

I wish I knew. The center housing had pitted o-ring grooves. Also in putting the engine together the last time, a part of the o-ring got twisted and a fraction of the white (teflon) strip got caught between the steel of the rotor housing and the center housing. However, that was several inches away from the point of burn-through. This time I filled the pits with JB weld, on my theory that the Hylomar gradually was forced out by combustion gasses.
I also took greater care in making sure the sides of the rotor housings were clean  (and filled any pits there with JB-weld too).  The most obvious thing were the cracked/missing chrome around the spark-plug hole and traces of melted rotorhousing alu at the edge. Gasses tunneling their way out to the edge underneath the steel/chrome sleeve? Ed's theory of overheating due to lack of coolant (leaking right radiator) is probably more likely.

Finn