| Also known as | E403 |
| Diagram | Fig. 3 — OIL PUMP AND RELEASE VALVE · ref 7 |
| Subsystem | engine bottom |
| Listed in parts books | 1960–1962, 1964–1971, 1974, 1976–1980 |
Valve spring first valve
Small spring for the oil pump check valve inside the crankcase oil pump assembly on Triumph twins.
This is the spring for the oil pump check valve, sitting in the oil pump and release valve assembly down in the crankcase. Despite the parts book calling it out under a valve-spring heading, the figure titles and the wider record on this number make clear it's the small spring that seats against the check valve ball in the oil pump, part of what keeps oil pressure where it belongs in the feed circuit. The older E403 stamp on this same part is just the pre-numeric-system tag for the identical piece, so if your book or an old box of parts shows E403, that's this spring.
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It shows up across a long run of catalog entries covering oil pump, release valve, manifold, and tappet figures, which tells you this spring has been used across a wide swath of Triumph twin production rather than one narrow window. Given how small and inexpensive a part this is, it's one worth keeping on the shelf rather than trying to reuse a tired one during an oil pump rebuild.
If you're rebuilding the oil pump or chasing an oil pressure gremlin, this spring is cheap insurance to swap out along with the check valve ball and pump gaskets while everything's apart. Call the shop if you want us to check exact fitment against your engine number before you order.
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