Damage on TD 049 crankcase

Dave P. Tue Feb 18, 2020 7:38 pm

Anybody ever seen this?

I recently acquired this thin wall TD. The compression is pretty good and it doesn't appear to have been disassembled or if it was the guy knew how. The curious thing is that the bottom of the rod appears to be undamaged. The inside of the crankcase definitely has been scored. Maybe a chip left from machining did this? Or was it over-reved?

dckrsn Tue Feb 18, 2020 8:10 pm

I've seen that, Dave. There was a thread about it
a while ago, but I don't remember enough to find it.
The bulge was attributed to dull cutters used for
milling inside the case for lower rod end clearance.
I seem to remember someone seeing it on a brand
new engine.
Nice looking old TeeDee. I see the oil hole on the crank
end of the piston rod. I'm guessing a thin wall cylinder?
Bob

**Cribbs74** Tue Feb 18, 2020 9:26 pm

What Bob said, poor tools and an early piston.

balogh Wed Feb 19, 2020 12:50 am

I also remember seeing that bulge of a shade only on one of my TD-s crankcase but not being too protruding, I did not attribute too much of significance to it. Main operational stresses in the crankcase material are expected to arise parallel to the bulge and not perpendicular to it -as a longitudinal crack once let it be seen at the backplate below- so I think there is no reason to worry about it.

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Damage on TD 049 crankcase

Damage on TD 049 crankcase

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Re: Damage on TD 049 crankcase