| Also known as | E3905 |
| Diagram | Fig. 1 — CRANKSHAFT AND CONNECTING RODS · ref 4 |
| Subsystem | engine bottom |
| Listed in parts books | 1960–1962, 1964–1965, 1967–1968, 1970–1971 |
CRANK PLUG SLOT LNG 20TPI
Slotted 20 TPI plug that seals the sludge trap passage in the Triumph crankshaft.
This is the crankshaft plug that seals off the sludge trap tube inside the crank. Every pre-unit and unit Triumph engine has a hollow passage bored into the crankshaft that acts as a centrifugal oil filter, and this plug is what closes off that passage after the tube is fitted and cleaned. It shows up in the parts book under the CRANKSHAFT AND CONNECTING RODS figure, with a slotted head and 20 TPI thread, and it carries the older E3905 number in earlier books.
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Owners doing a rebuild or just servicing the sludge trap need to pull this plug to get at the tube for cleaning, and put it back afterward. The catalog record shows this part was superseded by 71-2800, so if your parts book or a supplier lists that number instead, it's the same plug under a later factory designation.
We carry it as 70-3905 at the counter. If you're not sure which crank or engine generation you're working on, bring in the old plug or give us a call before ordering.
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