Please wait…

Please wait while we process your order,
do not press the back button…

nut Genuine Porsche part 90110438203

Code: 90110438203

Genuine Porsche part

nut

The product code 90110438203 was also found on these diagrams

103-000 - cylinder head nut

Cylinder head / Cylinder with piston 356B / 356C 1960-1965

103-000 - nut

Cylinder head / Cylinder with piston 914-6 1970-76

Additional information:

• This part is brand new and unused.
• Please verify that it is 100% suitable for your specific vehicle before purchase to ensure compatibility.

Before purchasing thoroughly check part to confirm compatibility.

Related products

3 3 3

Cylinder head nut. Porsche 911 1965-89 / 356 / 912

90110438204/1

Product Information

Cylinder Head Nut
Sold each - 24 required for the 911

Maintain the integrity and reliability of your Porsche engine rebuild with this OE Match Cylinder Head Nut 90110438204. Designed for use on Porsche 356B, 356C, 912 and classic 911 air-cooled engines, this precision-engineered fastener plays a critical role in securing the cylinder head assembly to the engine.

Fits:

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 1978-1983 3.0L / SC
Porsche 911 1984-1986 3.2L
Porsche 911 1987-1989 3.2L G50
Porsche 911 1975-1977 3.0L Turbo (930)
Porsche 911 1978-1989 3.3L Turbo (930)
Porsche 356B 1959-63
Porsche 356C 1963-65

Diagram Ref No 17

Although small in size, cylinder head nuts are among the most important fasteners in any engine. They provide the clamping force required to maintain an effective seal between the cylinder heads, cylinders and engine case, ensuring correct compression, combustion efficiency and long-term engine reliability.

Manufactured to OE Match specifications, this cylinder head nut is ideal for engine rebuilds, top-end overhauls, cylinder head refurbishment and concours restorations.

What Does a Cylinder Head Nut Do?

The cylinder head nut secures the cylinder head assembly to the engine using the cylinder head studs.

Its primary functions include:

Maintaining cylinder head clamping force
Ensuring correct cylinder sealing
Supporting combustion chamber integrity
Maintaining engine compression
Preventing cylinder head movement
Supporting reliable engine operation
Helping prevent oil and combustion leaks

Correct clamping force is essential for maintaining engine performance and durability.

Why Do Cylinder Head Nuts Fail?

Cylinder head nuts are exposed to repeated heat cycles, vibration and engine loads throughout their service life.

Common causes of deterioration include:

Corrosion
Thread wear
Fatigue from repeated heat cycles
Over-tightening
Incorrect installation procedures
Engine overheating
Age-related degradation
Damage during previous rebuilds

In older air-cooled Porsche engines, decades of service can leave original hardware weakened or unsuitable for reuse.

Symptoms of Worn or Damaged Cylinder Head Hardware

Potential warning signs include:

Loss of cylinder sealing
Compression leaks
Oil seepage around cylinder heads
Difficulty achieving correct torque settings
Damaged threads
Corroded hardware
Uneven clamping loads
Engine rebuild inspection failures

Many of these issues are discovered during engine disassembly rather than during normal operation.

When Should Cylinder Head Nuts Be Replaced?

Replacement is strongly recommended when:

Rebuilding an engine
Carrying out a top-end overhaul
Replacing cylinder head studs
Refurbishing cylinder heads
Corrosion is present
Threads show signs of wear
Factory specifications require replacement

Most professional Porsche engine builders replace critical fastening hardware during major engine work to ensure long-term reliability.

Why Replacement Matters

Reusing worn or damaged cylinder head hardware can compromise engine sealing and reliability.

Benefits of replacement include:

Correct clamping force
Improved sealing performance
Reduced risk of leaks
Improved engine reliability
Professional rebuild standards
Long-term durability
Factory-correct restoration quality
Greater peace of mind

For classic Porsche engines, replacing critical hardware is inexpensive insurance against future engine issues.

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

90110438204

90110438203

90110438202

61610438200

90110438200

93010438201

90110438204

The product you are viewing cross references to these numbers

Enter your VAT number here and click Verify:

nut Genuine Porsche part 90110438203