Crankshaft seal. This part number supersedes to 99911302951 Genuine Porsche part 99911302950

• Porsche 911 1965-1968 2.0L / 912 SWB (F)
• Porsche 356 1950-55Porsche 356A 1955-59
• Porsche 356B 1959-63Porsche 356C 1963-65
• Porsche 914 (1970-1976)

• Prevents gearbox oil from leaking around the mainshaft.
• Maintains proper lubrication within the transmission.
• Protects gearbox components from oil loss.
• Prevents dirt, moisture and contaminants from entering the gearbox.
• Supports reliable transmission performance and longevity.
• Helps maintain correct gearbox oil levels.

• Gearbox oil leaks beneath the vehicle.
• Oil residue around the transmission housing or shaft area.
• Gradual loss of gearbox oil.
• Difficulty maintaining correct transmission fluid levels.
• Contamination of surrounding components with oil.
• Increased transmission noise caused by reduced lubrication.
• Premature wear of gearbox bearings and internal components.
• Burning oil smells if leaking oil contacts hot surfaces.

• Mainshaft oil seals are subjected to constant shaft rotation, vibration, heat and prolonged exposure to transmission oil. Over time, the sealing lip can harden, wear or lose elasticity, reducing its ability to maintain an effective seal.
• A leaking oil seal can allow gearbox lubricant to escape, potentially reducing lubrication to critical internal components. If left unresolved, low oil levels can accelerate wear of gears, bearings and synchronisers, leading to costly transmission repairs or rebuilds.
• Replacing a worn mainshaft oil seal helps preserve correct gearbox lubrication, prevents oil leaks and protects internal transmission components from premature wear. An OE Match replacement restores the integrity of the gearbox sealing system and helps ensure reliable long-term transmission performance.

Crankshaft Oil Seal 

Protect your classic Porsche engine from oil leaks with this Crankshaft Oil Seal. This high-quality oil seal is manufactured to OE specifications, providing a reliable seal around the crankshaft where it exits the engine casing. Constructed from durable, oil-resistant materials, it is designed to withstand high temperatures, engine oil and constant crankshaft rotation while delivering long-lasting performance.

Fits:

• Porsche 356 1950-55
• Porsche 356A 1955-59
• Porsche 356B 1959-63
• Porsche 356C 1963-65
• Porsche 912E 4CYL 1976
  

Diagram ref no 47

Whether you're rebuilding an engine, replacing a leaking seal or carrying out preventative maintenance, this OE Match crankshaft oil seal offers dependable sealing performance and factory-style fitment.

What Does the Crankshaft Oil Seal Do?

The crankshaft oil seal prevents engine oil from escaping where the crankshaft passes through the engine case while keeping dirt, dust and moisture away from internal engine components.

Its key functions include:

• Preventing engine oil leaks
• Maintaining correct engine oil pressure
• Protecting the crankshaft opening from contamination
• Supporting long-term engine reliability

A correctly functioning seal is essential for keeping the engine clean, lubricated and operating efficiently.

Why Do Crankshaft Oil Seals Fail?

Over time, the sealing lip is subjected to continual contact with the rotating crankshaft, as well as heat and exposure to engine oil.

Common causes of failure include:

• Age-related hardening of the seal
• Heat cycling
• Wear of the sealing lip
• Oil contamination
• Incorrect installation
• Crankshaft surface wear

As the seal deteriorates, engine oil can begin to seep or leak from the crankshaft opening.

When Should It Be Replaced?

Replacement is recommended if:

• Oil is visible around the crankshaft area
• The seal shows signs of hardening or cracking
• The engine is being rebuilt
• The flywheel or pulley has been removed
• Preventative maintenance is being carried out on an older engine

Replacing the seal during engine work is inexpensive preventative maintenance that can help avoid future oil leaks and unnecessary labour costs.

Porsche 356 & 912 Engine Seals

Engine oil seals play a vital role in maintaining the reliability of classic Porsche engines. As rubber seals age, they gradually lose their flexibility and sealing ability, allowing oil leaks to develop that can affect engine cleanliness and reliability.

Replacing crankshaft oil seals during routine servicing or engine rebuilds helps maintain correct lubrication, reduce oil loss and protect valuable engine components. OE Match seals are manufactured to provide factory-style fitment and dependable long-term performance, making them an ideal choice for restoration and maintenance projects.

Benefits of Replacing the Crankshaft Oil Seal

• Prevents engine oil leaks
• Maintains proper engine sealing
• Protects against dirt and moisture ingress
• Ideal during engine rebuilds
• Long-lasting, oil-resistant materials