Peterbilt 375/377 Fuel Tank Caps

Frequently Asked Questions About Peterbilt 375/377 Fuel Tank Caps

Will this fuel tank cap fit my Peterbilt 375 or 377 without modification?

Fuel tank caps in this category are designed to match the fuel tank neck and thread pattern used on Peterbilt 375 and 377 models. However, fuel tank sizes and neck configurations can vary by production year and tank supplier, so it's important to check the cap's thread diameter and style against your existing cap before ordering. If you're unsure, measuring your current cap or referencing your tank's part number is the safest way to confirm a proper fit.

What materials are these fuel tank caps made from, and how do they hold up over time?

Fuel tank caps are typically offered in chrome-plated steel, stainless steel, or durable plastic/composite construction. Chrome and stainless options tend to resist corrosion and road grime better over the long haul, while composite caps can offer a lighter-weight, cost-effective alternative. Regardless of material, regular cleaning helps maintain the seal and finish, especially in caps exposed to road salt or harsh weather.

Do these caps include a locking feature to prevent fuel theft?

Some fuel tank caps in this category are available with locking mechanisms, while others are non-locking, vented, or non-vented designs. If fuel security is a concern, look for a locking cap option and confirm it comes with keys or a compatible keying system. Locking caps are a popular upgrade for drivers who park in high-traffic areas or want extra peace of mind on long routes.

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

Whether your Peterbilt requires a vented or non-vented fuel cap depends on your truck's fuel system design. Vented caps allow air to enter the tank as fuel is used, which is necessary on many setups to prevent vacuum lock, while non-vented caps are used on systems with a separate venting mechanism. Installing the wrong type can lead to fuel delivery issues, so it's best to match the replacement cap to the venting style of your original equipment.

Is installing a replacement fuel tank cap something I can do myself?

In most cases, yes. Replacing a fuel tank cap is a straightforward, tool-free task that simply involves removing the old cap and threading on the new one, making sure it seats and seals properly. After installation, it's a good practice to check for a snug fit and confirm there are no fuel odors or leaks around the cap before getting back on the road.