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Crankcase Parts

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DISPLAYING 17 to 20 (of 20 products)
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91110751200/1
Product Information
Product Information
Oil pressure relief piston
This OE Match oil pressure relief piston is a replacement piston used in the engine crankcase oil pressure relief system. It is designed to match the original Porsche-style fitment and helps regulate oil pressure within the engine lubrication circuit.

Fits:
Porsche 911/930 1974 - 1989
Porsche 964 1989 - 1994
Porsche 993 1995 - 1998
Porsche 996 Turbo / GT2 2001 - 2005
Porsche 997 Turbo / GT2 2005 >>
Porsche 996 GT3 / 997 GT3

Diagram ref no 16

The oil pressure relief piston works with the relief spring and guide components inside the engine block/crankcase. Its job is to help control excess oil pressure by allowing oil to bypass when pressure reaches the required limit, protecting the lubrication system and helping maintain consistent oil flow to critical engine components.

Functions
•  Helps regulate engine oil pressure
•  Works with the oil pressure relief spring and guide sleeve
•  Helps protect the engine from excessive oil pressure

•  Supports correct oil flow through the lubrication system
•  Helps maintain reliable lubrication of bearings and internal engine parts
•  Provides an OE Match replacement for the original relief piston
•  Suitable for engine rebuilds, crankcase service, and oil pressure repairs

The oil pressure relief piston is exposed to constant oil flow, heat, pressure, and engine wear particles. Over time, the piston can become scored, worn, sticky, or damaged, which may affect oil pressure regulation. A worn or sticking piston can contribute to low, high, or unstable oil pressure, so replacement is recommended during engine overhaul or when oil pressure control issues are being investigated.

When to replace
•   Oil pressure is too high, too low, or unstable
•   The original piston is scored, worn, sticking, or damaged
•   The engine has suffered internal wear or contamination
•   The crankcase oil pressure relief system is being serviced
•   The oil pressure relief spring, guide sleeve, or plug is being replaced
•   The engine is being rebuilt or overhauled
•   There are concerns about correct lubrication system operation

Where it fits on the car
This piston fits inside the engine crankcase/oil pressure relief valve assembly. It sits in the crankcase and is used with the relief spring and guide sleeve to control oil pressure in the engine lubrication system.



Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

91110751200
91110751200

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Special Order item
99911342641::1
Product Information
Product Information
Rear Main Oil Seal. 90 x 110 x 12.
Fitting Position: Transmission End, Inner Diameter: 90 mm, Outer diameter: 110 mm, Width: 12 mm, Radial Shaft Seal Design

porsche

Fits:
Porsche 964 1989-94
Porsche 993 1994-98
Porsche 996 Turbo / GT2 / GT3 MKI

Porsche 944 - All models including 944S, 944 Turbo & 944S2 built 1982-1991

Porsche 924S - All models built 1986-1988

Porsche 928 - All models built 1986-1995

Porsche 968 - All models built 1992-1995


Click 'Zoom in' for large parts diagram.
Diagram Ref No. 21



Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99911342641
99911342641
311.898
21074
569.120

The product you are viewing cross references to these numbers
99911342641/1
Product Information
Product Information
Rear Main Oil Seal. 90 x 110 x 12.
Fitting Position: Transmission End, Inner Diameter: 90 mm, Outer diameter: 110 mm, Width: 12 mm, Radial Shaft Seal Design.

Fits:
Porsche 964 1989-94
Porsche 993 1994-98
Porsche 996 Turbo / GT2 / GT3 MKI

Porsche 944 - All models including 944S, 944 Turbo & 944 S2 built 1982-1991
Porsche 924S - All models built 1986-1988
Porsche 928 - All models built 1986-1995
Porsche 968 - All models built 1992-1995

Diagram Ref No. 21



Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99911342641
99911342641
21074
99911321440
99911321540
99911324240
99911326440
99911327040
99911342640
99911342641
99911346140
569.120

The product you are viewing cross references to these numbers
Clearance Sale
SR067U
Product Information
Product Information
USED Exhaust Head Bolt Repair Kit.
This is a used part which has been fitted and used briefly then taken off the vehicle due to not meeting expectations of the customer. This part is in good working order. Ideal for restoration specialists, collectors, or workshops looking for components at reduced cost.

Condition: 
This Exhaust Head Bolt Repair Kit is a briefly used part. It has some fitting imperfections but in good / reusable working order.
Please see the gallery of images before purchasing.

Fits:
  • Porsche Boxster 986 2.5L 1997-99
  • Porsche Boxster 986 2.7L 1999-02
  • Porsche Boxster S 986 3.2L 1999-02
  • Porsche Boxster 986 2.7L 2003-04
  • Porsche Boxster S 986 3.2L 2003-04
  • Porsche Boxster 987 2.7L 2005-08/08
  • Porsche Boxster 987 S 3.2/3.4L 2005-08/08
  • Porsche 996 C2 3.4L 1997-08/01
  • Porsche 996 C4 3.4L 1997-08/01
  • Porsche 996 C2 3.6L 09/01-2005
  • Porsche 996 C4 3.6L 09/01-2005
  • Porsche 996 C4S 3.6L 09/01-2005
  • Porsche 996 TURBO 2000-05
  • Porsche 996 GT2 2001-05
  • Porsche 996 GT3 MKI 1999-02
  • Porsche 996 GT3 MKII 2003>>
  • Porsche 996 GT3 RS 2003-04
  • Porsche 997 MK1 Carrera 2 3.6L 2005-08
  • Porsche 997 MK1 Carrera 2S 3.8L 2005-08
  • Porsche 997 MK1 Carrera 4 3.6L 2005-08
  • Porsche 997 MK1 Carrera 4S 3.8L 2005-08
  • Porsche Cayman 2.7L 987C 2006-08
  • Porsche Cayman S 3.4L 987C 2005-08  
DISPLAYING 17 to 20 (of 20 products)
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About Crankcase Parts

Precision Crankcase Parts – Strength, Balance, and Reliability for Porsche Engines

The crankcase forms the core of every Porsche engine, housing key rotating components such as the crankshaft, bearings, and connecting rods. It provides structural rigidity, oil containment, and precise alignment for the engine’s moving parts — making it critical to both performance and longevity.

At Design911, we offer a wide range of precision-engineered crankcase components, including bearing shells, seals, breather valves, dowels, plugs, and fasteners, all manufactured to exacting tolerances. Each part is crafted from high-strength, heat-resistant materials to ensure lasting durability and performance under the most demanding driving conditions.

Whether you’re restoring an air-cooled 911 or maintaining a modern 992, our manufacturer-quality crankcase parts ensure perfect fitment, oil-tight sealing, and reliable performance for years to come.

What Do Crankcase Parts Do?

Crankcase components perform vital structural and lubrication roles within the engine, protecting internal parts and maintaining pressure balance.

Core Functions:

  • House and support the crankshaft, connecting rods, and bearings.
  • Contain and distribute oil to lubricate moving components.
  • Maintain structural rigidity to prevent vibration and misalignment.
  • Control crankcase ventilation to reduce oil contamination and pressure build-up.

In performance and classic Porsche engines alike, the crankcase ensures stability, smooth rotation, and reliable oil management — key to consistent power and reduced wear.

Why Do Crankcase Parts Fail?

Over time, crankcase components can degrade due to heat cycles, vibration, oil contamination, and mechanical fatigue. When neglected, these failures can lead to oil leaks, pressure imbalance, and even catastrophic engine damage.

Common Causes of Failure Include:

  • Oil seal wear causing leaks and pressure loss.
  • Bearing fatigue from prolonged high load or low oil pressure.
  • Warped surfaces due to overheating or corrosion.
  • Clogged breather valves causing pressure build-up and oil blow-by.
  • Fastener fatigue leading to structural loosening or vibration.

Replacing worn crankcase parts during an engine rebuild or maintenance interval is essential to preserve oil control, alignment, and crankshaft integrity.

Why Replace with Precision-Engineered Crankcase Parts?

High-quality crankcase components ensure your Porsche engine retains its strength, sealing capability, and precise alignment — essential for performance, reliability, and longevity.

Key Benefits:

  • Restores internal alignment for smooth crankshaft rotation.
  • Prevents oil leaks and pressure loss, maintaining engine performance.
  • Improves lubrication control and bearing life.
  • Reduces vibration and noise caused by worn or loose components.
  • Crafted from corrosion- and heat-resistant materials for lasting strength.
  • Perfect fitment and tolerance for air-cooled and water-cooled Porsche engines.

Engineers and restorers trust precision crankcase parts to maintain Porsche’s legendary reliability and mechanical balance — whether on the road or the track.

Highlights:

  • Comprehensive range of crankcase seals, bearings, bolts, and breather components.
  • Precision-machined parts designed for high-load, high-temperature performance.
  • Manufacturer-quality materials and tolerances.
  • Perfect for classic engine restorations and high-performance rebuilds.
  • Improves oil management, structural rigidity, and reliability.
  • Compatible with air-cooled and modern Porsche engine architectures.

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