TINWID1919 Diesel Fuel Cap 3½" Nominal for International Trucks — Aluminum Non‑Vented with Stainless Safety Chain

TINWID1919's 3½" nominal diesel fuel cap is an aluminum, non-locking replacement made to fit International/Navistar tanks requiring a vented cap and ships with a stainless steel safety chain.

If you operate or maintain International trucks that list part number 3591620C2, this cap is designed as a direct-fit replacement for the common 3 1/2" opening. The cap is machined from lightweight aluminum for corrosion resistance and includes a durable stainless steel safety chain so you won't lose the cap while fueling. It is a non-vented style, so confirm your fuel tank uses an external venting system before purchase.

How do I confirm this cap fits my truck?

Measure the diameter of your existing filler neck and compare it to the 3½" nominal size; this product replaces caps that match International/Navistar part 3591620C2. Check whether your original cap is non-locking and non-vented to ensure compatibility. If your current cap has a keyed lock or internal vent, this unit will not be a functional swap.

• Measure across the filler opening — should be approximately 3.5 inches
• Verify your original part number or compare to 3591620C2
• Confirm your tank uses external venting (tank must be vented)
• Ensure your truck accepts a non-locking cap

What are the construction and durability features?

The cap is formed from aluminum to resist rust and reduce weight compared with steel alternatives. It comes with a stainless steel safety chain that prevents loss during refueling and improves longevity in corrosive environments. The non-vented design keeps contaminants out when paired with a vented tank system.

• Lightweight, corrosion-resistant aluminum body
• Stainless steel safety chain for secure retention
• Non-vented construction — suitable only for vented tanks
• Simple, durable fit for frequent fueling use

Can I use this if my tank requires venting?

Yes — this cap is meant for fuel systems that already incorporate proper venting elsewhere on the tank. Because the cap itself is non-vented, it will not provide vapor relief; using it on a sealed, non-vented tank can cause pressure issues. Always follow your vehicle manufacturer’s ventilation requirements.

• Designed specifically for tanks with independent venting
• Do not use on sealed or non-vented tanks
• Prevents ingress of dirt and moisture when paired with vents
• Check vehicle service manual for vent placement

Who is this for: Fleet managers, owner-operators, mechanics, and maintenance teams who run International/Navistar trucks requiring a 3½" nominal non-locking fuel cap will find this a straightforward replacement. It's ideal when you need a corrosion-resistant aluminum cap with a retention chain and a direct match to part number 3591620C2. If your vehicle needs a locking or vented cap, consider an alternate model; otherwise this cap provides a simple, durable, low-maintenance solution for compliant, vented fuel systems.