X-Mozilla-Keys:                                                                                 
BruceT2598@aol.com wrote:

Today I had a new experience that I considered may be interesting to the
group. Occasionally I search the metal scrap yards for rotaries. I've always
found it delightful to pay for a core by the pound. In this case, fifteen
cents a pound. Amongst the pile of dead Chevrolets, Fords and Toyotas I found
three rotaries: two 12As and one 1988 13B. Besides the usual beating these
cores take from being tossed around by cranes with huge magnets, this 13b had
some unique damage visible from the outside. The core plugs in the rear
housing looked as though they had been hammered on from the inside. In fact,
one was completely missing. I immediately jumped to the conclusion that some
poor fool had filled the engine  water and let it freeze. To cut to the
chase, I was very wrong. 

Once I had the engine at the shop and mounted on the
stand, the series of events that led to the engine's demise began to unfold.
The first note in the autopsy report was that the oil pump had water
contaminated oil in it. If you have never seen this, it is green and creamy.
So I concluded that the engine had been running when the water entered the
oil pan. Next was that the rear thrust bearing had nearly welded itself to
the thrust washer. At this point I was kind of stumped. It looked like a
simple case of a frozen engine, but why the bearing failure?. Once I had the
housings separated, It all became clear. 

The housings has large blued areas
concentrating around the lower (combustion / exhaust) areas. The rotor
bearings were rough and chewed up. Then I noticed a missing section of the
combustion O-ring groove wall and everything seemed to come together. This
engine had suffered the classic failure of the groove wall, but this time the
driver had tried to push the engine to complete destruction. The rotor
bearings showed complete failure on their outer edges but looked OK within a
centimeter from the center in both directions. The rotor thrust surfaces were
mildly scuffed as though they had reached a temperature close to softening.

The rotor sides had large blued spots on them. It looks like the combination
of the bearing failure and the additional heat caused them to start wobbling
and rubbing against the side and intermediate housings. By the way, the
combustion O-rings (orange) had disintegrated to a mush consistency. The
engine still turned and had compression even with this catastrophic damage.

Hopefully we can use this information to predict how a rotary will react in
coolant system failure modes. I'll try to take some measurements tomorrow to
see if the rotor housings shrunk or the iron housings warped. Based on the
bluing, I think that everything in the engine is basically junk. (I'll
probably sell it back to the scrap yard for seven cents a pound). The neat
thing is that the engine never locked up, even though the owner really
toasted it!
Bruce Turrentine

 
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