Peterbilt 387 Fuel Tank Caps

Frequently Asked Questions About Peterbilt 387 Fuel Tank Caps

Will this fuel tank cap fit my Peterbilt 387 without modification?

Fuel tank caps for the Peterbilt 387 are designed to match the factory neck size and thread pattern used on this model, so a properly listed cap should thread on and seal without modification. That said, fuel tank necks can vary slightly depending on the tank supplier and model year, so it is a good idea to compare the thread diameter and locking mechanism of your current cap to the product specifications before ordering.

Is a locking fuel cap necessary, or is a non-locking cap sufficient?

A locking fuel cap adds a layer of protection against fuel theft and tampering, which is a common concern for trucks that sit overnight at truck stops or unattended lots. A non-locking cap will still seal the tank properly and is a lower cost option, but many owner-operators and fleets prefer the added security of a locking design, especially given ongoing fuel prices.

What materials and finishes are available for these fuel caps?

Fuel tank caps for the Peterbilt 387 are commonly available in chrome-plated steel or polished aluminum, and some are offered in plain or painted finishes to match the rest of the truck. Chrome and polished finishes tend to hold up well against weather exposure, but regular cleaning helps maintain their appearance over time.

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

Most diesel fuel tanks require a vented cap to allow air to enter the tank as fuel is drawn out, preventing a vacuum lock that can restrict fuel flow to the engine. If your Peterbilt 387 originally came with a vented cap, replace it with the same type. If you are unsure which style your truck uses, check the cap you are replacing or consult your parts manual before purchasing.

How difficult is it to install a replacement fuel tank cap, and are keys included with locking caps?

Installation is typically straightforward and only requires threading the new cap onto the fuel tank neck by hand, with no special tools needed. For locking caps, keys are generally included with the product, but if a cap is sold as a replacement for a lock cylinder already in use, be sure to check the product listing to confirm whether keys are provided or if it is designed to work with your existing key set.