Oil Pressure Relief Valve

Oil pressure relief plug extractor Porsche 911 / 964 / 993 / 996 / 997

Tolerance between the pressure relief plug and its galley are very close, and the slightest bit of gunk, corrosion, or bur will cause the plug to freeze up in the oil passage. A magnet is rarely powerful enough to overcome the seized plug, and leaving it in place is never an option.
Using STOMSKI RACING's Oil Pressure Relief Plug Extractor makes the task of removing the stuck plug a breeze, and allows you to ensure clean oil passages, and a properly operating bypass system.

The collet-based tool slides easily into the open end of the seized plug and a simple turn or two of the internal socket head cap screw expands the tool, grasping the plug to ensure easy removal.

Anodized Aluminum.

Oil pressure relief plug.

Fits:
Porsche 356B / 356C
Porsche 912
Porsche 911 65-77
Porsche 914

Diagram ref no 54

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Related, superseded, cross reference or alternative numbers for comparison.

99906401002

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Porsche Oil Pressure Relief Valve 

The oil pressure relief valve 90110728520 is an important component in the lubrication system of classic high-performance Porsche engines. Used in racing and motorsport-derived models such as the Porsche 911 RSR 2.8, 911 RSR 3.0 and Porsche 914-6 GT, this valve helps regulate oil pressure to ensure safe and consistent engine lubrication.

Fits:

• Porsche 911 RSR 2.8
• Porsche 911 RSR 3.0
• Porsche 914-6 GT  

These engines were developed for high-performance and competition use, where maintaining stable oil pressure is critical to protecting internal engine components during high RPM operation.

What the Oil Pressure Relief Valve Does

The oil pressure relief valve regulates pressure within the engine’s lubrication system. As oil is pumped through the engine, pressure builds within the system. If the pressure exceeds a predetermined level, the relief valve opens to divert excess oil back into the system.

This process helps:

• Maintain stable oil pressure throughout the engine
• Prevent excessive pressure that could damage seals and gaskets
• Protect oil coolers and lubrication channels
• Ensure proper lubrication during high RPM operation
• Maintain reliability in high-performance engines

Without a properly functioning relief valve, oil pressure can rise beyond safe levels, increasing the risk of component failure.

Why Oil Pressure Relief Valves Fail

Over time, oil pressure relief valves can wear or become contaminated with debris from the lubrication system.

Common causes of failure include:

Internal wear
Continuous operation under high pressure can wear the internal spring or valve seat.

Contamination
Debris or sludge in the oil system can cause the valve to stick or operate incorrectly.

Spring fatigue
The internal spring that controls opening pressure can weaken with age.

Improper oil maintenance
Old or contaminated oil can accelerate internal wear of lubrication system components.

Symptoms of a Faulty Oil Pressure Relief Valve

• Unstable or fluctuating oil pressure readings
• Excessively high oil pressure
• Oil leaks caused by excessive pressure
• Reduced lubrication efficiency in extreme conditions
• Potential damage to seals, oil coolers or engine components

Replacing a worn relief valve helps maintain correct oil pressure and protects valuable engine components.

Why You May Need to Replace This Valve

Protect High-Performance Porsche Engines
RSR and GT engines operate under demanding conditions where stable oil pressure is critical.

Maintain Correct Oil System Operation
A properly functioning valve ensures the lubrication system operates within safe pressure limits.

Prevent Engine Damage
Excessive oil pressure can damage seals, oil coolers and internal components.

Ideal for Engine Rebuilds or Restorations
When rebuilding or restoring classic Porsche racing engines, replacing critical oil system components ensures long-term reliability.

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

90110728520

The product you are viewing cross references to these numbers