O-Ring Seal 18 X 2,5. Porsche 911 / 964 / 993  ›  99970714340

O-Ring Seal 18 x 2.5mm
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On Porsche 911 models from 1984–1986, it is used in the gearbox oil cooler assembly. On Porsche 964 and 993 models, it is used for the heater box water drain pipe.

Fits:

• Porsche 911 1984-1986 3.2L
• Porsche 964 (911) C2 1989-93
• Porsche 964 (911) C4 1989-93
• Porsche 964 (911) RS 3.6L 1991-93
• Porsche 964 (911) RS 3.8L 1991-93
• Porsche 964 (911) TURBO 3.3L 1991-93
• Porsche 964 (911) TURBO 3.6L 1991-93
• Porsche 993 (911) C2 1994-97
• Porsche 993 (911) C4 1994-97
• Porsche 993 (911) RS 1994-97
• Porsche 993 (911) C2S 1994-97
• Porsche 993 (911) C4S 1994-97
• Porsche 993 (911) TURBO 1994-96
• Porsche 993 (911) GT2 1994-97
• Porsche 993 (911) TURBO S 1994-97

Diagram Ref No 6 or 19

What Does It Do?

The O-ring creates a seal between adjoining components, helping prevent unwanted leakage.

In the gearbox oil cooler application, it helps maintain an oil-tight connection. In the heater box drain assembly, it helps seal the relevant drain pipe connection.

Why Does It Fail?

Common causes include:

• Rubber hardening with age
• Exposure to heat and temperature changes
• Compression and loss of elasticity
• Cracking or splitting
• Damage during removal or installation

When Should It Be Replaced?

Replace if the O-ring is brittle, flattened, cracked or damaged.

Replacement is recommended when dismantling the gearbox oil cooler connection or heater box water drain pipe, particularly where the original seal has deteriorated.

Checks & Installation

Inspect the sealing groove and mating surfaces for dirt, corrosion or damage.

Ensure the replacement O-ring is correctly seated without twisting or pinching. Check the connection for leaks after reassembly.

Key Features

• Replacement O-ring seal
• Dimensions: 18 x 2.5mm
• Fits Porsche 911 (1984–1986) gearbox oil cooler applications
• Fits Porsche 964 / 993 heater box water drain pipe applications
• Helps maintain leak-resistant connections
• Suitable for servicing and restoration

Porsche 911 / 964 / 993 Gearbox Oil Cooler & Heater Box Seals

The Porsche 911, 964 and 993 use rubber O-ring seals in various mechanical and drainage connections to maintain correct sealing and prevent unwanted leakage.

This 18 x 2.5mm O-ring is specifically used in the 1984–1986 Porsche 911 gearbox oil cooler and the heater box water drain pipe on Porsche 964 and 993 models.

Replacing deteriorated seals helps maintain reliable operation and prevent leaks during servicing or restoration.

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

99970714340

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