Head nut washer. Porsche 911 1978-89  ❭  99903109101

Cylinder head nut washer (Head nut washer)
This washer is used under the cylinder head nuts on Porsche 911 engines (1978–1989). It’s a precision washer made to the same style and dimensions as the original, helping the head nut seat correctly against the engine hardware.
Price is for each, 24 required per engine.

Fits:
Porsche 911 1978 - 1989

Diagram ref no 16

The washer spreads the clamping load from the head nut, helping maintain consistent torque retention and protecting mating surfaces from damage caused by concentrated pressure.

• It’s supplied per washer (price is for each) and 24 washers are required per engine.

It provides a stable, even load surface beneath each head nut, supporting correct tightening and helping the cylinder head fastening system maintain consistent clamp force over time - especially important on engines that see repeated thermal expansion and contraction.

•  Distributes head nut load to reduce point-stress on components
•  Helps maintain more consistent clamping force as the engine heat-cycles
•  Supports proper seating of the head nut for reliable assembly during rebuilds

Old washers can become corroded, deformed, or marked from previous torque cycles. Reusing tired hardware can affect how evenly the head nuts clamp, which can compromise long-term sealing and reliability. Fresh washers help restore proper seating and load distribution during rebuild work.

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Related, superseded, cross reference or alternative numbers for comparison.

99903109101

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