SHIM, OIL PUMP RELIEF SPRING
Relief valve spring shim oil pump
Precision shim for adjustment of the relief valve spring in the oil pump. This shim is used to regulate maximum oil pressure by adjusting the preload of the relief valve spring. An essential component when overhauling or adjusting the oil pump.
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Function Relief valve spring pressure adjustment |
Application Oil pump L-134 engine |
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Engine type Chain and gear drive |
Effect Regulates maximum oil pressure |
Features
- For adjustment of oil pump relief valve
- Regulates opening of pressure relief valve
- Each shim increases pressure by approx. 5 PSI
- Suitable for both oil pump versions
- For professional engine overhaul
★ Precision component for adjusting the oil pump relief valve. Essential during engine overhaul and optimisation of lubrication.
Application
This shim is used in oil pumps of jeeps fitted with the L-134 'Go Devil' engine. Applicable to both early chain-driven oil pumps (early MB/GPW/M201/early CJ-2A) and later gear-driven oil pumps (late CJ-2A/CJ-3A/CJ-3B/M38/M38A1). The shims are fitted beneath the relief valve spring to increase the opening pressure of the pressure relief valve.
Installation notes
The shim is positioned beneath the relief valve spring in the oil pump. Each shim increases the opening pressure of the relief valve by approximately 5 PSI. The standard opening pressure is 40 PSI at 2000 rpm. Note: increasing spring preload only affects maximum oil pressure at higher engine speeds, not idle pressure. Idle pressure is determined by bearing clearance and pump volume. Always verify oil pressure with a calibrated gauge after adjustment.
Compatibility
Suitable for all variants of the L-134 oil pump: both early chain drive with domed cover and late gear drive with flat cover. Note: shims are used during manufacture to calibrate the pump. During overhaul, only use if the relief valve spring is weakened or higher pressure is desired. Do not use for low idle pressure caused by worn bearings — this will not solve the problem.
Historical context
The relief valve in L-134 oil pumps opens at a standard 40 PSI to prevent excessive pressure. During wartime production, shims were used to individually calibrate each pump to the desired opening pressure.
This description was generated automatically. Unsure about fitment? Contact us at info@willys.be.
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This part is intended for the restoration of historic military vehicles. Fitting, aligning, deburring or reworking is part of that work and is inherent to the nature of these goods. Dimensional variation also exists between original vehicles.
Installation requires technical knowledge of the vehicle. Unsure whether this part suits your version? Ask us before purchase at info@willys.be.
ALL_CATEGORIES : Oil Pump Drive Gear Willys MB Ford GPW M201
This part fits:
| Model | Years |
|---|---|
| Military jeeps | |
| Willys MB (early) | 1941, 1942 |
| Willys MB | 1942, 1943, 1944, 1945 |
| Ford GPW (early) | 1942 |
| Ford GPW | 1942, 1943, 1944, 1945 |
| Hotchkiss M201 | 1956, 1957, 1958, 1959, 1960, 1961, 1962, 1963, 1964, 1965, 1966 |
| Willys M38 | 1950, 1951, 1952 |
| Willys M38A1 | 1952, 1953, 1954, 1955, 1956, 1957, 1958, 1959, 1960, 1961, 1962, 1963, 1964, 1965, 1966, 1967, 1968, 1969, 1970, 1971 |
| CJ series | |
| Jeep CJ-2A | 1945, 1946, 1947, 1948, 1949 |
| Jeep CJ-3A | 1949, 1950, 1951, 1952, 1953 |
| Jeep CJ-3B | 1953, 1954, 1955, 1956, 1957, 1958, 1959, 1960, 1961, 1962, 1963, 1964, 1965, 1966, 1967, 1968 |
📐 Diagrams & technical drawings
From the original Technical Manual TM 10-1513 — Maintenance Manual — only for Willys MB / Ford GPW (1942)
