8-Blade CNC Aluminum Water Pump

The FlowKooler 1687 is an aluminum hi-flow water pump engineered to address overheating and heat cycling issues in 1971-1977 Chevrolet trucks and other applications equipped with the 250/4.1L inline-6 engine. This water pump features a specifically designed impeller with an increased vane count and reduced vane clearance, which work together to achieve greater flow rates and higher head pressure. This enhanced circulation helps to efficiently remove heat from the engine and prevent temperature spikes. Constructed from durable aluminum, the 1687 water pump boasts an 8-vane CNC-machined impeller. This impeller is further protected against corrosive fluids by a Type II Class II military-grade surface coating, ensuring longevity and consistent performance. The pump body is made of aluminum, and it operates with a clockwise (CW) direction of rotation. The fan hub has a working height of 4-1/4 inches and a 5/8-inch shaft diameter, with a 3/4-inch male hose connection. Installation includes mounting gaskets, an installation sheet, and a FlowKooler decal. FlowKooler has been a pioneer in hi-flow pump technology, continually refining impeller designs for optimal cooling performance. The principle behind their design is that reducing the cycle time between the heat source (engine) and the heat sink (radiator) allows for more frequent heat dissipation, thereby lowering engine temperatures. This pump is particularly effective from 0-3,300 RPM. This water pump is compatible with a range of Chevrolet and GMC models including Blazer, C/K pickups and Suburbans, and vans from the mid-to-late 1970s. It is essential to verify that your vehicle's fan hub working height matches the 4-1/4 inch specification of this pump; alternative pumps are available for different hub heights (e.g., pump 1777cw for 3 7/8" or pump 1686 for 3 15/16").