PROJECT 51: The Mystery of The Cotter Pins. While cleaning out the gunk in the bottom of the oil pan (the sump in Brit-speak), I discovered half a dozen broken cotter pins and pieces thereof. At first I didn't know where they might have come from, but soon realized that these pins would have gone through the castellated nuts that clamp the connecting rod halves together around the crankshaft. The pins are meant to prevent the nuts from backing off under the high-vibration of the running engine.
I remembered that it seemed odd that only two of the eight rod nuts had pins when I dismantled the engine weeks ago, but I just chalked it up to a typical Brutus-ism.
It seems I owe him a (slight) apology. He apparently did put the pins in, but they were the wrong size (too small), and therefore didn't fit tightly in the holes. That high-vibration then caused them to rattle around in the holes until they broke and fell out. Luckily, the nuts had been torqued sufficiently that they didn't loosen on their own.
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| Sump with splash baffle and oil pick-up. |
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| Baffle and pick-up removed to clean sludge. |
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| Broken cotter pins from sump. Note how small they are. |
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| Crank in engine block. |
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| Rod cap without cotter pin. |
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| Rod cap with larger diameter cotter pin. |
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