Product Review: Cummins Coolant Bypass Kit Fleece Performance

Fleece Peformance built this coolant bypass kit for higher horsepower applications that put an increased demand on the cooling system.

Also, cylinder 5 and 6 typically run hotter due to restrictions in the factory exhaust manifold. This can cause excessive pressure in your cooling system and possibly a blown freeze plug. Enter Fleece Performance for the save.

Fleece Performance designed their coolant bypass kit with a secondary thermostat, that unlike other brands, works based on temperature instead of excessive pressure. This solves the problem before pressure becomes an issue by ensuring consistent temperatures across all six cylinders. Our kit comes with high quality AN o-ring fittings and AN hose connections with braided hose to ensure a leak free installation. The 2003-2007 5.9L automatic transmission version will eliminate the factory transmission fluid heat exchanger. The heat exchanger is not a fluid cooler; it was designed for use in cold climates to warm the transmission fluid with the engine coolant. It is not necessary for use in warm climates or high horsepower applications, nor does it detrimentally affect the trucks performance when removed.

All 2007-2016 6.7 trucks, both automatic and manual equipped transmissions, do not have a transmission fluid heat exchanger.

For customers with a 6.7L that has a heat exchanger, You will need a heater tube it can be purchased at your local Chrysler Dealership PN:68048997AA. It is very rare that a 6.7L has a heat exchanger, but we have had a few instances where it has been needed.

Flying Wrench Diesel Mechanic Advice: “This is a great product. As a proactive approach for our shop clients, every blown head-gasket repair comes with the coolant bypass kit from Fleece. We believe in this product so much we make sure our customer’s walk away with the best.”