Shop Peterbilt 357 & 378 Fuel Tank Caps

Time for a new aftermarket fuel tank cap? 4 State Trucks has you covered with our large inventory of Peterbilt 378 fuel tank caps. We have vented, non-vented, locking, and non-locking caps so you can find the perfect aftermarket fuel tank cap. Shop at 4 State Trucks for the best fuel tank caps in the business.

Peterbilt 357/378 Fuel Tank Caps

Peterbilt 357/378 Fuel Tank Caps are an essential component for keeping your Peterbilt truck's fuel system secure and functioning properly. This product lineup features a wide range of high-quality fuel caps, gaskets, and related accessories designed to fit various Peterbilt models, including the popular 357 and 378 models. Whether you need a replacement locking fuel cap, a non-vented lever-style cap, or an anti-siphon system, you'll find a variety of options to choose from. These fuel tank caps not only provide a tight seal to prevent leaks, but many also offer added security features to deter fuel theft. With a focus on durability, ease of use, and a perfect fit, the Peterbilt 357/378 Fuel Tank Caps product lineup ensures you can keep your truck's fuel system in top condition. Enhance the performance and protection of your Peterbilt with these essential fuel tank accessories.

Frequently Asked Questions About Peterbilt 357/378 Fuel Tank Caps

Will these fuel tank caps fit my specific year Peterbilt 357 or 378?

Our fuel tank caps are designed to fit Peterbilt 357 models from 1987-2007 and Peterbilt 378 models from 1986-2007. These caps feature a standard 4-inch diameter opening that matches OEM specifications. However, if your truck has aftermarket fuel tanks or has been modified, we recommend measuring your tank opening before ordering. The threading should be 8 threads per inch for proper fitment.

Are these caps vented or non-vented, and which type do I need?

We carry both vented and non-vented fuel tank caps. Vented caps are required for diesel applications to prevent vacuum buildup in the tank, which can cause fuel flow issues and potentially damage your fuel system. Non-vented caps are typically used for secondary or auxiliary tanks. Most Peterbilt 357/378 trucks require at least one vented cap on the primary tank. Check your current cap or consult your owner's manual to determine which type you need.

What's the difference between chrome-plated and stainless steel caps?

Chrome-plated caps offer a mirror-like finish at a lower price point but may show wear over time, especially in harsh weather conditions. Stainless steel caps cost more initially but provide superior corrosion resistance and maintain their appearance longer without peeling or flaking. For trucks operating in northern climates with road salt exposure, stainless steel is the recommended choice for long-term durability.

Do these caps come with new gaskets, and are they lockable?

Yes, all our fuel tank caps include new rubber gaskets to ensure a proper seal and prevent fuel evaporation. Most models feature a locking mechanism with two keys included. The locks use a standard cam-style design that's weather-resistant. If you need multiple caps keyed alike for fleet consistency, please contact our customer service team before ordering.

How do I know if my fuel cap needs replacement?

Replace your fuel cap if you notice any of these signs: difficulty removing or installing the cap due to damaged threads, visible cracks in the cap body or gasket, fuel odor around the tank area, or a check engine light related to evaporative emissions. A worn gasket can cause fuel vapors to escape, triggering emissions codes. Additionally, if your cap no longer clicks when tightening or the lock mechanism is frozen, it's time for a replacement.