Frequently Asked Questions About Kenworth W900A Fuel Tank Caps

Will these fuel tank caps fit my specific year Kenworth W900A?

Our Kenworth W900A fuel tank caps are designed to fit most W900A models from 1961 through 1990. However, some mid-80s models may have different tank configurations. We recommend checking your current cap size - standard sizes are typically 4-inch or 5-inch diameter. If you're unsure, measure your existing cap or contact us with your VIN for verification.

What's the difference between locking and non-locking fuel caps?

Locking fuel caps feature a built-in lock mechanism that requires a key to open, providing security against fuel theft and tampering. Non-locking caps use a standard twist-on design. Both types seal equally well when properly installed. Locking caps typically add about $15-25 to the price but offer peace of mind, especially for drivers who park in unsecured areas overnight.

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

Most Kenworth W900A models require vented fuel caps to allow air to enter the tank as fuel is consumed, preventing vacuum lock. Non-vented caps can cause fuel pump issues and poor engine performance. Unless your truck has been modified with a separate tank venting system, you'll need vented caps. All our W900A replacement caps come pre-vented unless specifically noted otherwise.

How difficult is it to install these fuel caps, and what tools do I need?

Installation is straightforward and typically takes less than 5 minutes per cap. No special tools are required - simply unscrew your old cap and thread on the new one. Make sure to clean the filler neck threads first and check the rubber gasket is properly seated. Hand-tighten until snug, then give an additional quarter turn. Over-tightening can damage the gasket and cause leaks.

What materials are these caps made from, and how long do they last?

Our fuel caps feature either chrome-plated steel or aluminum construction with fuel-resistant rubber gaskets. Chrome-plated steel caps offer superior durability and typically last 5-7 years with proper care. Aluminum caps are lighter and won't rust but may show wear sooner. The gaskets should be inspected annually and replaced every 2-3 years or if you notice any fuel odor or seepage around the cap.