Kenworth T300-T450 Fuel Tank Caps

Frequently Asked Questions About Kenworth T300-T450 Fuel Tank Caps

Will this fuel tank cap fit my Kenworth T300, T440, or T470?

Fuel tank caps can vary by tank manufacturer, neck diameter, and locking mechanism even within the same truck model range. Before ordering, check the thread size and diameter of your current cap or the tank fill neck, and compare it to the specifications listed on the product page. If you are unsure, our sales team can help confirm fitment based on your truck's VIN or tank details.

Should I choose a locking or non-locking fuel cap?

Locking fuel caps are a popular upgrade for fleet trucks and owner-operators who park in high-traffic areas, as they help deter fuel theft and tampering. Non-locking caps are simpler and quicker to use but offer no security. Many customers switch to a locking cap after experiencing a theft or siphoning attempt, so consider your parking situation and route history when choosing.

What materials are these fuel tank caps made from, and does it matter?

Fuel tank caps in this category are typically available in chrome-plated steel, stainless steel, or durable plastic/composite construction. Chrome and stainless options tend to hold up better against corrosion and road grime while also matching the polished look of other cab accessories, whereas composite caps are often lighter and more budget-friendly. Choose based on how much exposure to weather and road salt your truck sees, along with your preference for appearance.

How do I know if I need a vented or non-vented fuel cap?

Most modern diesel fuel systems require a vented cap to allow air to enter the tank as fuel is drawn out, preventing a vacuum lock that can starve the engine of fuel. Using the wrong type can cause performance issues or difficulty refueling. If your truck came with a vented cap originally, replace it with the same type; when in doubt, check your Kenworth's service documentation or ask our team before purchasing.

Is installation something I can do myself, or does it require a mechanic?

Replacing a fuel tank cap is generally a simple task that most drivers and owner-operators can handle without a shop visit. In most cases, it is as easy as removing the old cap by unscrewing or unlatching it and threading or securing the new one in its place. If your cap includes a locking mechanism or tether, take a moment to review the included hardware and instructions to ensure it seats and seals properly against the fill neck.