C3900956 XCMG GR2605 motor grader bowl plug

C3900956 (3900956) is a specialized sealing component designed for the cylinder blocks of Cummins ISB, ISDe, and QSB series engines. Also known as a cylinder block water plug or blanking cap, it serves as a critical sealing element within the engine’s cooling and lubrication systems. Manufactured by stamping high-quality SPHC cold-rolled steel sheet, the component features a bowl-shaped structure and undergoes surface galvanization or phosphating treatments to prevent corrosion. Utilizing its inherent elasticity and an interference fit, it seats tightly into designated ports within the cylinder block. Its primary function is to seal the process holes within the block’s coolant passages and oil galleries, thereby preventing leaks of coolant and engine oil while simultaneously shielding the interior from external dust and contaminants. This ensures the proper operation of the engine’s cooling and lubrication systems, making it suitable for demanding operating conditions—including heavy-duty applications and extreme temperature environments—while offering convenient installation and reliable sealing performance.

Technical Specifications

– Part Number: C3900956 (3900956)
– Brand: Dongfeng Cummins (DCEC)
– Type: Engine Cup Plug (Water Plug / Core Plug)
– Material: SPHC High-Quality Cold-Rolled Steel Sheet (Thickness: 1.5–2.0 mm)
– Compatible Engines: Cummins ISB6.7, ISDe4.5, ISDe6.7, QSB6.7, and B5.9 Series
– Structure: Stamped cup-shaped structure with an elastic rolled rim; threadless design secured via interference fit
– Key Dimensions: Outer Diameter φ45 mm, Inner Diameter φ38 mm, Height 12 mm (Designed to fit corresponding process holes in the cylinder block)
– Surface Treatment: Hot-dip galvanizing / Phosphating; rust-resistance rating meets a 48-hour salt spray test standard with no corrosion
– Installation Method: Press-fit (interference fit); can be used in conjunction with sealant to enhance sealing performance
– Alternative Models: 3926802, 3900955, 4932299 (Universally interchangeable)
– Weight: Approx. 0.08 kg/unit
– Sealing Medium: Engine coolant, engine oil

Application Scenarios

Primarily designed for Cummins series engines installed in Dongfeng commercial vehicles and construction machinery. Serving as a dedicated sealing component for cylinder block process holes, it is widely utilized across various heavy-duty operating conditions:

– Dongfeng Vehicle Models: Tianlong, Tianjin, Hercules, Auman, and other medium-to-heavy-duty trucks equipped with ISDe/ISB/QSB series engines
– Construction Machinery: 18–26 ton wheel loaders, motor graders, bulldozers, and excavators (equipped with QSB6.7 or B5.9 engines)
– Applicable Conditions: Harsh environments involving long-distance heavy hauling, mining sites, high-altitude/extreme-cold regions, high-temperature/high-humidity climates, frequent start-stop cycles, etc.
– Installation Location: Sides, bottom, and rear of the engine cylinder block; fits into process holes reserved for water and oil passages, distributed strategically across key sealing areas of the block Core Function: Seals process ports in the cylinder block, preventing leaks of coolant and engine oil, isolating external contaminants, and ensuring the sealing integrity and stability of the cooling and lubrication systems.