Gates 31335 Radiator Cap

OE Type Radiator Cap for Closed Systems

The Gates 31335 OE Type Radiator Cap is built for closed coolant recovery systems that require a threaded coolant bottle cap with accurate pressure control. It is a direct-fit cooling system service part for select Audi, Volkswagen, and Porsche applications, including Audi A8 Quattro, Audi A6, Volkswagen Golf, and Porsche Boxster models.

Key Features

• OE Type Radiator Cap for closed coolant recovery systems
• Threaded coolant bottle cap design
• 20 psi pressure rating with an SAE pressure range of 18-22 psi
• Filler neck inside diameter: 1.31 in. (33 mm)
• Filler neck outside diameter: 2.16 in. (55 mm)
• Filler neck depth: 0.88 in. (22 mm)
• Shell diameter: 2.27 in.
• Constructed from corrosion-resistant metal or high-quality plastic, depending on application
• Manufactured to meet or exceed OEM specifications in function, form, and fit

Product Details

Gates OE Type Radiator Cap 31335 is engineered to maintain proper cooling system pressure in vehicles equipped with a closed coolant recovery system. By controlling pressure within the specified range, the cap helps support stable coolant circulation and consistent system operation. This part is a strong match for long-tail searches such as Audi A8 Quattro radiator cap 20 psi, Volkswagen Golf threaded coolant bottle cap, and Porsche Boxster OE type radiator cap. Gates 31335 is also referenced for Audi A6, Audi 80, Audi 100, Volkswagen Jetta, and related applications where the listed neck dimensions and pressure rating match the original equipment design.

The Gates OE Type Radiator Cap line focuses on OE-style replacement parts built for accurate fit and pressure control. For buyers replacing a worn or leaking cap on an Audi A4, Audi S6, or Volkswagen Cabriolet cooling system, this product line provides a direct replacement approach that follows OEM-style specifications.

This part cross-references Dorman - HELP 46025 and Hayden 105 for the same application.

Common Problems This Part Addresses

• Coolant loss from a cap that no longer seals properly
• Pressure fluctuations in a closed cooling system
• Overflow or recovery bottle issues caused by a weak spring or worn seal
• Cooling system warning signs tied to an incorrect cap rating
• Fitment problems when replacing an OE-style threaded coolant bottle cap

Installation Notes and Tips

Verify the filler neck inside diameter, outside diameter, and depth before installation. This cap is specified for a 20 psi system and a closed coolant recovery setup, so the pressure rating must match the vehicle’s original requirement. Inspect the filler neck, sealing surface, and recovery bottle threads for damage before installing Gates 31335. Confirm application details for Audi, Volkswagen, and Porsche models listed in the fitment data, including early-production notes where shown.

Quality Assurance

Gates manufactures this radiator pressure cap to meet or exceed OEM specifications in function, form, and fit. Corrosion-resistant construction supports long service life and accurate pressure control, and the design meets environmental regulatory standards intended to reduce air pollution.

Compatible Vehicles

• Fits 1997-2003 Audi A8 Quattro, N/A
• Fits 2001-2003 Audi S8, N/A
• Fits 1997-2000 Audi A8, N/A
• Fits 1994-1998 Audi Cabriolet, N/A
• Fits 1997-1998 Porsche Boxster, N/A
• Fits 1995-1997 Audi A6, N/A
• Fits 1995-1997 Audi A6 Quattro, N/A
• Fits 1996 Audi A4, N/A, Early; 20 psi Pressure Rating; OE Type Radiator Cap
• Fits 1996 Audi A4 Quattro, N/A, Early; 20 psi Pressure Rating; OE Type Radiator Cap
• Fits 1995-1996 Audi S6, N/A
• Fits 1993-1995 Audi 90, N/A
• Fits 1988-1991 Audi 90, N/A
• Fits 1993-1995 Audi 90 Quattro, N/A
• Fits 1988-1991 Audi 90 Quattro, N/A
• Fits 1989-1994 Audi 100, N/A
• Fits 1989-1994 Audi 100 Quattro, N/A
• Fits 1992-1994 Audi S4, N/A
• Fits 1990-1994 Audi V8 Quattro, N/A
• Fits 1985-1993 Volkswagen Cabriolet, N/A
• Fits 1987-1993 Volkswagen Fox, N/A
• Fits 1988-1992 Audi 80, N/A
• Fits 1988-1992 Audi 80 Quattro, N/A
• Fits 1989-1991 Audi 200, N/A
• Fits 1989-1991 Audi 200 Quattro, N/A
• Fits 1990-1991 Audi Coupe Quattro, N/A
• Fits 1985-1990 Volkswagen Golf, N/A
• Fits 1980-1990 Volkswagen Jetta, N/A
• Fits 1986-1988 Audi 5000 Quattro, N/A
• Fits 1984-1988 Volkswagen Corsar, N/A
• Fits 1982-1988 Volkswagen Quantum, N/A
• Fits 1980-1987 Audi 4000, N/A
• Fits 1984-1987 Audi 4000 Quattro, N/A
• Fits 1986-1987 Audi Coupe, N/A
• Fits 1983-1985 Audi Quattro, N/A
• Fits 1980-1984 Volkswagen Rabbit Convertible, N/A
• Fits 1981-1982 Volkswagen Atlantic, N/A
• Fits 1980-1981 Porsche 924, N/A
• Fits 1981 Volkswagen Rabbit Pickup, N/A