Frequently Asked Questions About Peterbilt 352 Fuel Tank Caps

Will these fuel tank caps fit my specific year Peterbilt 352?

Our Peterbilt 352 fuel tank caps are designed to fit all model years of the 352, which were produced from 1969 to 1981. These caps use the standard Peterbilt threading that remained consistent throughout the 352's production run. However, if your truck has aftermarket fuel tanks, we recommend measuring your current cap's diameter (typically 4 inches) and thread pitch to ensure compatibility.

What's the difference between locking and non-locking fuel caps, and which should I choose?

Locking fuel caps feature a built-in key mechanism to prevent fuel theft and tampering, while non-locking caps use a simple twist-on design. If you park in unsecured areas, haul long distances, or have experienced fuel theft, we strongly recommend locking caps. Non-locking caps work well for trucks primarily used in secure yards or for local operations. Both types provide the same seal quality and fuel system protection.

Are these caps vented or non-vented, and why does it matter?

Most of our Peterbilt 352 fuel caps are vented designs, which allow air to enter the tank as fuel is consumed, preventing vacuum lock and ensuring smooth fuel flow. Non-vented caps can cause fuel starvation issues and tank collapse in older trucks without modern tank venting systems. Unless your 352 has been retrofitted with a separate tank vent system, you'll need vented caps for proper operation.

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

Our fuel caps come in three primary materials: chrome-plated steel, polished aluminum, and heavy-duty plastic. Chrome and aluminum caps typically last 5-10 years with proper care, offering superior durability and classic appearance. Plastic caps are more economical and resist corrosion but may need replacement every 2-3 years. All options include quality rubber O-ring seals that should be inspected annually and replaced if cracked or compressed.

How do I know if my fuel cap needs replacement, and what problems can a bad cap cause?

Replace your fuel cap if you notice: a strong fuel smell around the tank area, visible cracks in the cap or seal, difficulty turning or securing the cap, or rust/corrosion on metal caps. A failing fuel cap can trigger check engine lights in newer retrofitted engines, allow water contamination in your fuel system, create vacuum issues affecting engine performance, and result in fuel evaporation losses. Most drivers replace caps every 3-5 years as preventive maintenance.