0psi Crankcase Check Vlv 5/8in Barb Inlet/Outlet

The 0psi Crankcase Check Valve with 5/8 inch barb inlet and outlet is an essential breather system component for performance engines running positive crankcase ventilation (PCV) systems. Designed by REDHORSE PERFORMANCE, this check valve prevents backflow of exhaust gases and atmospheric moisture into the crankcase while allowing controlled evacuation of blow-by gases. Whether you're building a forced-induction engine, upgrading an existing carbureted platform, or fine-tuning a fuel-injected application, a properly functioning crankcase check valve protects internal engine components from contamination and pressure buildup that can compromise ring seal integrity and bearing longevity.

This check valve operates on a zero-psi differential, meaning it opens with minimal crankcase pressure—ideal for naturally aspirated and mild boost applications where precise flow control is critical. The dual 5/8 inch barb connections accommodate standard heater hose or silicone breather tubing, allowing seamless integration into custom PCV setups without adapter fittings. The compact body measures 3.83 inches long and 1.5 inches in diameter, enabling installation in tight engine bays where space is premium. At just 0.185 pounds, weight penalty is negligible, yet the internal poppet mechanism delivers reliable one-way flow management, preventing pressure spikes and crankcase sludge accumulation caused by atmospheric backflow.

Street and track enthusiasts benefit most from this valve when routing crankcase vapors to a catch can, atmospheric dump, or closed-loop intake system. Carburetor-equipped engines gain particular advantage, as traditional PCV systems often struggle with blow-by management under high load. The 5/8 inch barb inlet and outlet accept both rigid and flex hose, making it compatible with custom engine builds across domestic and import platforms. Installation is straightforward: position the valve between the crankcase vent source and destination line, secure with stainless steel hose clamps, and verify zero-psi operation during idle to confirm proper crankcase evacuation.