1973-1977 C3 Coolant System Expansion Tank 339185 - OEM Number(s) (339185)
Protect your Corvette’s cooling system with a heavy-duty replacement expansion tank built for durability and correct fit.
By 1973, GM transitioned Corvettes to a non-pressurized plastic expansion tank for improved cooling efficiency. This high-quality heavy-duty plastic expansion tank is a direct replacement for 1974–early 1977 Corvettes and can also serve as a correct replacement on 1973 models. Designed to perform under high-heat conditions, the tank captures overflow coolant to prevent radiator back pressure and fluid loss. With precise factory-style dimensions and mounting points, it installs cleanly and maintains the authentic look under your Corvette’s hood.
Fits the Following Corvette Models:
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1973 Corvette (C3, replacement use)
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1974–1977 Corvette (C3, early plastic expansion tank models)
Material/Finish
Dimensions
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Overall width: 15 1/2 in (394 mm)
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Overall height: 6 3/4 in (171 mm)
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Mounting spacing: 11 1/8 in (283 mm)
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Thickness: 5/8 in (16 mm)
Features/Benefits
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Heavy-duty plastic construction withstands high engine bay temperatures
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Correct replacement for 1974–1977E Corvettes; also fits 1973 applications
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Captures overflow coolant, preventing radiator back pressure and overflow
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Designed with factory-correct mounting points for easy installation
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Maintains OEM-style fit and function under the hood
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GM reference part number: 339185
Because Details Matter
A Corvette’s cooling system is vital to both performance and preservation. Choosing the right expansion tank isn’t just about function — it’s about ensuring that under-hood components look and perform exactly as GM intended. From the translucent plastic finish to the precise mounting points, this tank proves that every detail matters in a faithful restoration.
Also known under these part numbers: (For reference only)
- 145152
- 25-120559-1
- 339185
- 686420079774
- A2368
- E6784