Phoddar Locking Diesel Fuel Tank Caps 3.5" ID — 2-Pack for Freightliner 108SD & Cascadia, Die-Cast Aluminum, Vented

Built to meet or exceed OEM specifications, this Phoddar locking fuel cap set offers a durable, leak-resistant solution for vented semi-truck diesel tanks. The kit includes two 3.5" inside-diameter caps, extra rubber gaskets, safety chains, and matching keys so you get ready-to-install parts that resist corrosion, high temperatures, and everyday road wear.

Will this cap fit my Freightliner model?

Phoddar engineered this cap to replace Freightliner OEM part numbers and fit a wide range of models. Always measure your filler neck before ordering: the cap's inside diameter is 3.5" and it is intended for fuel filler tubes with an outer diameter about 3".

• Direct fit for Cascadia 113/125 (2008–2018), Columbia 112/120 (2001–2016), Century 112/120 (1996–2010).
• Compatible with Coronado (2003–2022), M2-112 (2005–2022), 108SD and related Freightliner lines.
• Replaces Freightliner 03-37017-002, 572.1018, 0334466002, 0337017002 and equivalents from Velvac/Tectran.
• Designed for vented diesel tanks with 220°F thermal relief; not threaded—they use a quarter-turn, 4-pin push-and-twist style.

How does this locking cap protect my fuel system?

The Phoddar cap uses a die-cast aluminum housing and a rubber sealing gasket to block contaminants and minimize evaporation. The keyed lock and reinforced housing reduce unauthorized access and installation damage while the vented design safeguards pressure relief requirements for diesel tanks.

• Heavy-duty aluminum alloy resists corrosion and mechanical wear.
• Rubber gasket ensures an airtight seal to reduce leaks and fumes.
• Keyed lock prevents fuel theft and unauthorized opening.
• Safety chain and bail keep the cap attached during refueling.

What comes in the package and how easy is installation?

The set ships with two locking caps, four replacement nitrile gaskets, two 13" safety chains with 7" bails, and four identical keys—so both sides or spare caps are covered. Installation is straightforward: clean the filler neck, seat a single gasket in the cap, then quarter-turn to lock; contact Phoddar with photos if you have sealing issues during installation.

• 2 x locking fuel caps (3.5" inside diameter), 4 x gaskets, 2 x chains, 4 x keys.
• One gasket per cap—do not stack gaskets; ensure filler neck is clean before fitting.
• Quarter-turn, push-and-twist closure matched to original 4-pin style.
• Vented cap with 220°F thermal relief for vented diesel tanks only.

What durability and performance features should I expect?

Phoddar caps are engineered for heavy-duty trucking conditions, with materials and construction chosen to extend service life and maintain sealing performance. The product undergoes engineering review and quality control to ensure compatibility, heat resistance, and corrosion protection.

• Die-cast aluminum body for strength and corrosion resistance.
• Thermal relief rated for up to 220°F in vented systems.
• Lock cylinder built for frequent use and keyed-alike convenience.
• Reinforced housing minimizes installation damage and wear.

Who is this for: Fleet managers, owner-operators, and maintenance technicians who need a reliable, OEM-compatible locking fuel cap for Freightliner trucks (including Cascadia, Columbia, Century, Coronado, M2-112 and related models). Choose this Phoddar set when you want keyed security, corrosion-resistant construction, full installation hardware, and components that meet or exceed the original equipment fit and function for vented diesel tanks.