Original Cummins engine parts Add oil cap C3973511

Built as a critical barrier for the engine’s lubrication system, this add oil cap features an advanced dual-seal design. The primary seal is a nitrile rubber (NBR) O-ring (Shore hardness 70±5) integrated into the cap’s inner groove, forming a tight seal with the oil filler neck to block oil leakage—tested to withstand 50kPa internal pressure with no seepage. The secondary seal is a flexible rubber flange that covers the filler neck opening, preventing dust, water, and debris from entering the engine when the cap is closed. This dual protection reduces oil contamination risks by 95%, avoiding abrasive wear on crankshafts and bearings caused by foreign particles

Engineered for the harsh conditions of Cummins engines, the cap uses premium materials for exceptional durability. The main body is crafted from glass-fiber reinforced nylon (PA66+30%GF) with a tensile strength of 180MPa, resisting impact and deformation even under accidental drops or tool collisions. The NBR seal resists degradation from synthetic and mineral engine oils, maintaining flexibility at temperatures ranging from -40℃ to 120℃—adapting to frigid cold starts and high-temperature engine operation. The external surface features a textured finish that enhances grip, preventing slippage even with oily hands, while the internal thread is reinforced with a metal insert to avoid stripping

Integrated with a built-in pressure-relief valve, the add oil cap maintains optimal pressure in the engine’s lubrication system. The valve automatically opens when the crankcase pressure exceeds 8-10kPa (a common issue during high-load operation) and closes when pressure returns to normal, preventing oil seal damage or oil leakage caused by excessive pressure. This function also avoids negative pressure in the crankcase, ensuring smooth oil suction by the oil pump and stable oil supply to critical components. The pressure-relief mechanism undergoes 100,000-cycle testing with no performance degradation, ensuring reliable operation for ≥200,000km

The add oil cap is designed for maximum user convenience and long-term cost savings. Its ergonomic hexagonal shape and textured surface allow easy hand tightening/loosening without tools, reducing oil addition time by 30%. The cap features a color-coded “OIL” marking and a bright yellow top, making it easily identifiable in cluttered engine compartments—preventing accidental misplacement. As a genuine OE part, it eliminates the risk of using ill-fitting aftermarket caps that cause oil leakage or system damage. Backed by a 1-year/100,000km warranty, it reduces lubrication system maintenance costs by 40% and extends engine service life by avoiding contamination-related wear