Part 99970146740 (superseded by 99970728541) is a 51 x 4.5 mm O-ring seal used across a wide range of Porsche models. Depending on the engine architecture, it serves either as a crankshaft main/nose bearing O-ring or an engine oil filler cap gasket
| Model / Generation |
Model Years |
Trims & Engines Covered |
Role / Location |
| Porsche 911 (G-Body) |
1974–1989 |
911 Base, 911SC (3.0L), Carrera (3.2L) |
Crankshaft main / nose bearing O-ring |
| Porsche 930 Turbo |
1978–1979, 1986–1989 |
930 Turbo Coupe (3.3L) |
Crankshaft main / nose bearing O-ring |
| Porsche 911 (964) |
1989–1994 |
Carrera 2, Carrera 4 (3.6L), Turbo (3.3L & 3.6L) |
Crankshaft main / nose bearing O-ring |
| Porsche 911 (993) |
1995–1998 |
Carrera, Carrera S, Carrera 4, Carrera 4S, Targa, Turbo (3.6L) |
Crankshaft main / nose bearing O-ring |
| Porsche Boxster (986) |
1997–2004 |
Base (2.5L & 2.7L), Boxster S (3.2L), S Special Edition |
Engine oil filler cap gasket |
| Porsche 911 (996) |
1999–2005 |
Carrera, Carrera 4, Carrera 4S, Targa (3.4L & 3.6L) |
Engine oil filler cap gasket |
| Porsche 911 (996 Mezger) |
2001–2005 |
Turbo, Turbo S, GT2, GT3 (3.6L) |
Crankshaft main / nose bearing O-ring |
Additional Cross-Referenced Models
- Oil Filler Cap Cross-Compatibility. While standard OEM fitment charts focus on 1974–2005 models, Porsche parts counters note that this 51 x 4.5 mm gasket is included with certain replacement oil filler caps and cross-references to select later water-cooled vehicles (excluding later GT3 engines).
- Verification Note. If you are purchasing this O-ring for a post-2005 Porsche (such as a 987, 997, 718, or Cayenne), confirm whether your vehicle uses the updated oil filler cap assembly before ordering, as later models often specify a different cap-and-seal revision.
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