74140 Replacement Caps

The 74140 Replacement Caps from Moroso are essential fluid containment components designed for engine builders and performance enthusiasts who demand precision in their cooling and pressurization systems. These caps seal and regulate pressure in radiators and reservoirs, maintaining optimal operating conditions under high-performance and modified engine builds. Whether you're running a street engine, weekend track car, or full restoration project, replacement caps ensure your cooling system maintains proper seal integrity and prevents coolant loss during thermal cycles.

Moroso engineered these 74140 caps with precision threads and engineered rubber seals that withstand repeated thermal expansion and contraction without degradation. The design allows for proper pressure relief and venting, critical in engines where cooling system pressure directly impacts boiling point and heat transfer efficiency. Compact at just 0.1 lbs with a footprint of 5.4 x 1.55 x 7.2 inches, these caps integrate seamlessly into existing radiator and overflow tank assemblies without interference or fitment issues. Quality sealing materials resist coolant chemical degradation and maintain effectiveness across multiple seasons of use.

Mechanics and fabricators benefit most from stocking Moroso replacement caps when refreshing cooling systems on restorations, performance builds, or routine maintenance. If your cap threads are damaged, seals are cracked, or pressure relief has become inconsistent, these caps provide a reliable OEM-quality solution without rebuilding entire radiators. Installation is straightforward—simply thread onto your radiator neck or overflow tank and hand-tighten until the seal seats properly. For any modified engine or long-term build, keeping a 74140 cap on hand ensures you're never sidelined by a failed seal during critical testing or competition.