Hey oily rag,

Was there any evidence of of the little end seizing up? It looks like it snapped in tension or from bending. With perfect bearings on both end, the rod should be subject to pure compression and tension. the compression forces should be much greater than the tension forces. If it failed in compression and you'd have the break at 45 angle to the long direction of the rod.

Do you see evidence of fatigue? If you look at the fatigue fracture (possibly with a magnifying glass) you can typically see little lines where the tip of the crack kept inching forward, like the rings in a tree. The final brittle failure will look kind of frosted.


Originally Posted by oilyrag
Hi all,
Yes they go, and this is how it looks:-
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This engine was doing approx 3800rpm when this failure occurred. The history of the rods was unknown but they had been X-rayed 2000 miles before and looked ok. As Tiger says:-
If good replacement rods are available and you are unsure of history spring the bucks for new ones, cheap compared to new cylinders and cams and crankcases and such.

Wise words.