Gates 31720 Fuel Tank Cap

OE Equivalent Fuel Cap for Select BMW and Mercedes-Benz

Gates 31720 is an OE Equivalent Fuel Tank Cap built for direct replacement on a wide range of import and domestic applications. It is designed to meet or exceed OEM specifications while maintaining the fit and sealing characteristics needed for emission-control fuel systems.

The Gates OE Equivalent Fuel Cap line focuses on rugged construction and broad neck compatibility. This cap is made to work with shallow cam filler necks and is listed for vented, non-vented, and vented anti-surge applications, making it a practical replacement for many BMW 318i, 325i, 540i, and Mercedes-Benz 300E and 190E models.

Key Features

• OE Equivalent Fuel Cap design for factory-style replacement
• Meets or exceeds OEM specifications
• Heavy-duty construction for everyday fuel system use
• Fits shallow cam filler necks
• Works with vented, non-vented, and vented anti-surge systems
• Emission control venting
• OE performance rating
• Thread diameter: 1.5
• Shell diameter: 2.53 in
• Depth: 1.41 in
• Non-lockable design

Product Details

Gates 31720 is engineered as an OE-style fuel tank cap for vehicles that require a precise seal and correct venting behavior. It is a strong match for long-tail searches such as fuel cap for 1991-1996 BMW 318i, fuel tank cap for 1986-1993 Mercedes-Benz 300E, and replacement gas cap for 1978-1991 Honda Civic. This part number, 31720, is also referenced across multiple aftermarket catalogs for the same application.

This part cross-references Dorman - HELP 46139 and Standard Ignition 6810 for the same application.

Common Issues This Part Can Address

• Fuel cap warning light caused by a worn or leaking cap
• Fuel vapor loss from a damaged seal or poor cap fit
• Incorrect venting on emission-control fuel systems
• Difficulty matching the original filler neck style
• Replacement needs for cracked, aged, or missing fuel caps

Installation Notes and Tips

Verify filler neck style, thread diameter, and cap depth before installation. This Gates fuel cap is listed for shallow cam filler necks and emission-control applications, so matching the original neck design is important for proper sealing. Confirm vehicle fitment by year, make, and model before ordering, especially on BMW and Mercedes-Benz applications.

Quality Assurance

Gates OE Equivalent Fuel Caps are built to meet or exceed OEM specifications and are intended to deliver OE-style fit and function for fuel system service.