LO 10-5 Identify and describe the types, functions, construction features, and applications of diesel engine lubrication system components

Anti-Drainback Valve

Cartridge filters and spin-on oil filters, which are filter elements consisting simply of filter media enclosed by metal containers, require an anti-drainback valve. Spin-on filters usually have this valve built into the filter element, but the filter header—the component that the filter threads onto—contains the valve. The purpose of the drainback valve is to prevent the oil in the engine from returning to the crankcase when the engine is shut down. This permits the instantaneous buildup of oil pressure and immediate supply of oil to the engine after start-up. This valve usually consists of a one-way flow control valve in the center tube of a spin-on filter. Many drainback valves in filters are made of nitrile rubber. However, nitrile rubber diaphragms stiffen in extreme cold and may fail to seal in those conditions. Silicone rubber seals or steel valves are not prone to this problem. Detroit Diesel (DD)-series engines and other OEMs use a check valve in the oil pump pickup tube to prevent oil from draining back to the pan when the engine is shut down.