| Also known as | E7431 |
| Diagram | Fig. 2 — CRANKCASE · ref 39 |
| Subsystem | engine bottom |
| Listed in parts books | 1969–1970, 1974, 1976–1978 |
'O' ring - drain plug
O-ring for the crankcase or chaincase drain plug, keeping oil from weeping past the plug threads.
70-7431 is the O-ring used on a drain plug in the crankcase, and it also shows up in the chaincase and chains section of the parts books. It's a simple sealing ring that sits under or around the plug to keep oil from seeping out at the threads. Small part, but if it's flattened, cracked, or missing, you'll get a slow drip right where you don't want one.
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The legacy number for this one is E7431, so if your parts book or an old envelope of spares has that stamped on it, you're looking at the same ring. It turns up across a long run of catalog years, which tells you it's a part that stuck around largely unchanged.
Worth pulling and inspecting anytime you're in the crankcase or chaincase for other work. It's cheap insurance to keep — wait, no, it's just worth having a spare on hand since it's easy to overlook until you've got oil on the garage floor.
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