The Fleece Performance Coolant Bypass Kit is one of the most important reliability upgrades you can make to any Cummins-powered truck — covering the full platform range from 1994 12V trucks all the way through 2024 6.7L applications. Built out of necessity by Fleece Performance Engineering to address a well-documented and platform-wide cooling failure mode. The factory Cummins cooling system was designed to adequately cool a stock engine. As performance demands increase — or simply as these engines age — the rear cylinders suffer from insufficient coolant flow and experience the highest temperatures in the block. This creates excessive pressure buildup, especially at the rear of the block, which can blow out freeze plugs externally or the smaller diameter plugs under the valve cover, leading to catastrophic engine failure. Fleece's solution uses a secondary thermostat that operates based on temperature rather than pressure — unlike competing kits that only react after excessive pressure has already built up. This solves the problem before pressure becomes an issue by ensuring consistent coolant temperatures across all six cylinders. The complete kit includes high quality AN O-ring fittings and braided hose connections for a leak-free installation, available in braided black nylon or braided stainless steel finish depending on variant. Fitment covers the complete Cummins lineup from 1994 through 2024 — select your specific year range, engine, transmission type, and hose finish at checkout. Refer to the application notes below for your specific variant before ordering. Application Notes by Variant — Read Before Ordering: 2019–2024 6.7L Auto/Manual (FPE-CLNTBYPS-CUMMINS-19): Kit includes rear thermostat housing, front thermostat housing, new EGR cross-over tube gaskets, black braided nylon coolant bypass hose with AN fittings, and mounting hardware. Fits 2019–2024 Ram 2500/3500 6.7L 24V Cummins.Install Instructions Fleece Performance Coolant Bypass® for 2019+ Ram w/ 6.7L Cummins 2013–2018 6.7L Auto/Manual (FPE-CLNTBYPS-CUMMINS-1318): Kit includes rear thermostat housing, front thermostat housing, new EGR cross-over tube gaskets, black braided nylon coolant bypass hose with protective high temperature sleeve and AN fittings, and mounting hardware. For 2013–2018 trucks with a factory installed transmission fluid heat exchanger (uncommon but found in northern climates), an additional heater tube is required — available at your local Chrysler dealer, PN: 68048997AA.Install Instructions Fleece Performance Coolant Bypass® for 2007.5-2018 Ram with 6.7L Cummins 2007.5–2012 6.7L Auto/Manual (FPE-CLNTBYPS-CUMMINS-0712): Kit includes rear thermostat housing, front thermostat housing, new EGR cross-over tube gaskets, braided nylon coolant bypass hose with protective high temperature sleeve and AN fittings, exhaust back pressure sensor mounting block and back pressure sensor line, and mounting hardware. For 2007.5–2012 trucks with a factory installed transmission fluid heat exchanger, PN: 68048997AA is required from your Chrysler dealer. When using this kit with a Steed Speed exhaust manifold, verify the manifold vintage — older Steed Speed manifolds used a 1/4 NPT fitting that requires rework. The Fleece EBP line uses M12x1.0 flare fitting for the stock manifold.Install Instructions Fleece Performance Coolant Bypass® for 2007.5-2018 Ram with 6.7L Cummins 2006–2007 5.9L Auto — Black Nylon (FPE-CLNTBYPS-CUMMINS-0607): This kit will eliminate the factory transmission fluid heat exchanger on 2003–2007 5.9L auto transmission trucks. The heat exchanger is not a fluid cooler — it was designed for cold climate use only and is not necessary for warm climates or high horsepower applications. Kits for 2003 and newer include billet hose brackets. Fits 2006–2007 Dodge Ram 2500/3500 5.9L 24V Cummins automatic transmission only.Install Instructions Cummins Coolant Bypass 2006-2007 Auto Transmission Only.pdf 2006–2007 5.9L Auto — Stainless Steel (FPE-CLNTBYPS-CUMMINS-0607-SS): Same application and notes as above. Braided stainless steel hose finish. Fits 2006–2007 Dodge Ram 2500/3500 5.9L 24V Cummins automatic transmission only.Install Instructions Cummins Coolant Bypass 2006-2007 Auto Transmission Only.pdf 2003–2007 5.9L Manual — Black Nylon (FPE-CLNTBYPS-CUMMINS-MAN): For manual transmission 5.9L trucks across the full 2003–2007 range including 2004.5. No transmission heat exchanger on manual trucks — no additional parts required. Fits 2003–2007 Dodge Ram 2500/3500 5.9L 24V Cummins manual transmission.Instructions for Cummins Coolant Bypass Kit 2003-2007 Manual Transmission 2003–2007 5.9L Manual — Stainless Steel (FPE-CLNTBYPS-CUMMINS-MAN-SS): Same application and notes as above. Braided stainless steel hose finish. 2003–2005 5.9L Auto — Black Nylon (FPE-CLNTBYPS-CUMMINS-0305): This kit will eliminate the factory transmission fluid heat exchanger. Kits for 2003 and newer include billet hose brackets. Fits 2003, 2004, and 2005 Dodge Ram 2500/3500 5.9L 24V Cummins automatic transmission.Instructions for Cummins Coolant Bypass Kit 2003-2007 Manual Transmission 2003–2005 5.9L Auto — Stainless Steel (FPE-CLNTBYPS-CUMMINS-0305-SS): Same application and notes as above. Braided stainless steel hose finish.Install Instructions for Cummins Coolant Bypass 2003-2005 RAM Auto Transmission 1998.5–2002 VP44 Auto/Manual — Black Nylon (FPE-CLNTBYPS-CUMMINS-VP): Fits 1998.5–2002 Dodge Ram 2500/3500 5.9L VP44 24V Cummins, automatic and manual transmission.Instructions Coolant Bypass for Cummins 1998.5-2002VP 1998.5–2002 VP44 Auto/Manual — Stainless Steel (FPE-CLNTBYPS-CUMMINS-VP-SS): Same application as above. Braided stainless steel hose finish.Install Instructions Fleece Performance Coolant Bypass for 1998.5-2002 Ram with 5.9L Cummins 1994–1998 12V Auto/Manual — Black Nylon (FPE-CLNTBYPS-CUMMINS-12V): Fits 1994–1998 Dodge Ram 2500/3500 5.9L 12V Cummins, automatic and manual transmission.Instructions for Coolant Bypass Cummins 1994-1998 12V 1994–1998 12V Auto/Manual — Stainless Steel (FPE-CLNTBYPS-CUMMINS-12V-SS): Same application as above. Braided stainless steel hose finish.Instructions for Coolant Bypass Cummins 1994-1998 12V
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