Gates 31521 Radiator Cap

OE Type Radiator Cap for Reliable Cooling Control

The Gates 31521 OE Type Radiator Cap is built to maintain proper cooling-system pressure with OE-style fit and function. It is a standard cap with a 10 psi pressure rating, making it a direct-match choice for select Chevrolet G20, Chevrolet G30, GMC G2500, and GMC G3500 applications.

Gates OE Type Radiator Caps are made with corrosion-resistant metal or high-quality plastic, depending on application, to support long service life and consistent pressure control. The Gates 31521 is engineered to meet or exceed OEM specifications in form, fit, and function.

Key Features

• Brand: Gates OE Type Radiator Cap
• Part number: 31521
• Standard cap design
• 10 psi pressure rating; SAE pressure range 9-11 psi
• OE Performance comparison rating
• Filler neck inside diameter: 1.61 in (41 mm)
• Filler neck outside diameter: 2.13 in (54 mm)
• Filler neck depth: 0.75 in (19 mm)
• Shell diameter: 2.33 in
• Coolant recovery system: optional system

Product Details

This Gates radiator cap is intended for cooling systems that require accurate pressure regulation and OE-style sealing dimensions. The 31521 radiator cap supports proper system pressure to help maintain coolant performance in vehicles such as the Chevrolet G20 and GMC G3500, while matching the specified filler neck dimensions for the listed applications. If you are replacing a worn or leaking radiator cap on a Chevrolet G30 or GMC G2500, this OE Type cap provides a direct-fit service part built to Gates specifications.

This part cross-references Standard Ignition RC-12 for the same application.

Common Problems This Part Can Address

• Loss of cooling-system pressure from a worn cap seal
• Coolant overflow caused by a cap that no longer holds rated pressure
• Pressure fluctuation in the radiator neck
• Improper fit on the specified filler neck dimensions
• Cooling-system service needs on older Chevrolet and GMC vans and trucks

Installation Notes and Tips

Verify the filler neck inside diameter, outside diameter, and depth before installation. Confirm the vehicle uses a 10 psi radiator cap and compare the existing cap style to the Gates 31521 OE Type Radiator Cap. For best results, inspect the radiator neck, cap seal surface, and coolant level before installing the replacement cap.

Compatible With 1983-1991 Chevrolet G20, N/A; 1983-1991 Chevrolet G30, N/A; 1983-1991 GMC G2500, N/A; and 1983-1991 GMC G3500, N/A. Fits 1983-1991 Chevrolet G20, 1983-1991 Chevrolet G30, 1983-1991 GMC G2500, and 1983-1991 GMC G3500 with the listed 10 psi OE-type radiator cap application.

Quality Assurance

Gates manufactures this radiator cap to meet or exceed OEM specifications in function, form, and fit. The construction uses corrosion-resistant materials selected for long service life and accurate pressure control, and it meets or exceeds environmental regulatory standards intended to reduce air pollution.