6.5L diesels run a little warmer but if you're seeing hi temps and you're at slow speed or under a load then you may need more coolant flow and balanced circulation.

Flowkooler designed a high flow water pump 1677-HO for these conditions. It has a CNC machined billet impeller with increased vane count and a reduced casting-to-impeller vane clearance. It achieves greater flow rates, higher head pressure and a more balanced and efficient flow. The impeller color is due to Type II Class II military grade surface coating which protects against corrosive fluids.

FlowKooler introduced the first hi flow pumps and continues to improve impeller design. Why is increased flow so important to cooling a hot GM diesel engine? Because it has been proven time and time again that reducing the cycle time between the heat source and the heat sink creates more opportunities to shed heat and drop engine temperatures.

Please select the correct fan clutch mounting style when ordering. You can use either pump on any year 6.5 with a serpentine belt setup as long as you have the matching clutch, however. From the factory, years up until 1999 used the bolt on clutch and 1999.5+ used the spin-on threaded clutch.

From 0-3,300 RPM…Nothing Beats a FlowKooler! Why replace with a stock pump when we can beat their price and performance!?