Arnold OEM-751-10300 Genuine Parts Replacement Gas Cap for 4.5-6.5 HP Engines

What It Is

This is a replacement gas cap for lawn mowers and small engines in the 4.5 to 6.5 horsepower range. It seals the fuel tank to prevent leaks and evaporation, and includes a built-in vent to maintain proper air pressure for consistent fuel flow.

Fitment & Compatibility

Before buying, check these three things:

• Engine HP range: Confirmed for 4.5–6.5 HP engines (common on push mowers, some riding mowers, and log splitters).
• Neck diameter: Measures approximately 1.5 inches inside diameter. Measure your current cap or tank neck with a ruler—if it’s close, this will likely fit.
• Tank depth: The cap’s stem is about 1 inch long. Ensure your tank opening is deep enough to accept it without bottoming out.
• OEM vs. aftermarket: This is an Arnold OEM part, so it’s a direct replacement for many Briggs & Stratton, Tecumseh, and MTD engines. Not guaranteed for every brand—check your engine model number if in doubt.

Key Things to Know

• Vent function works: The cap vents properly, which prevents vacuum lock that can stall the engine. No need to drill or modify.
• Easy install: Screws on by hand in under 30 seconds—no tools required. Just remove the old cap and thread this one on.
• Common gotcha: If your tank neck is slightly larger or smaller than 1.5 inches, this cap may leak or not seal. Measure first.
• Quality note: Made from durable plastic with a rubber gasket. Some users report the gasket can dry out over time, but replacement gaskets are available separately.

Should You Buy It

If you need a reliable, vented gas cap for a 4.5–6.5 HP engine and your tank neck is about 1.5 inches, this is a solid, low-cost fix. It’s a direct OEM replacement for many common mower brands, installs in seconds, and solves stalling or fuel smell issues. Skip it if your engine is outside the HP range or if you need a cap for a different neck size.