GM Genuine Parts Thermostat Bypass Pipe Seal 12658352 | 2017-2023 Duramax 6.6L L5P

Thermostat Bypass Pipe Upper O-Ring

This replacement upper O-ring is designed for the thermostat bypass pipe, helping maintain a proper seal and prevent coolant leaks.

• Direct replacement upper O-ring
• Seals the thermostat bypass pipe connection
• Helps prevent coolant leaks
• Recommended during water pump service