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- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 356B 1959-63
- Porsche 356C 1963-65
- Porsche 914 (1970-1976)
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Related, superseded, cross reference or alternative numbers for comparison.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
The product you are viewing cross references to these numbers
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 914 (1970-1976)
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:
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