Fleece Coolant Bypass Kit (Manual Trans) for 2003-2007 Dodge Ram 5.9L Cummins

A stick shift 5.9L has the same hot rear cylinders as the autos. This is the bypass for your truck.

Here's the issue: the rear cylinders on the 5.9/6.7L Cummins are short on coolant flow and run the highest temps. That builds excessive pressure, especially at the rear of the block, and can blow out freeze plugs externally or the smaller plugs under the valve cover. Fleece adds a secondary thermostat that, unlike other brands, opens on temperature instead of excessive pressure, keeping all six cylinders even before pressure becomes a problem.

Fleece says the bypass is one of the most important additions you can make for the reliability and longevity of a Cummins.

What it does

• Lowers coolant temperature at the rear cylinders
• Ensures consistent temperatures across all six cylinders
• Prevents damaging coolant pressure build up
• Secondary thermostat that works on temperature, not excessive pressure
• Braided hose and AN O-ring fittings for a leak-free install

Specs

• Transmission: Manual
• Engine: 5.9L Cummins
• Part number: FPE-CLNTBYPS-CUMMINS-MAN
• CARB EO: D-834-9

Why we run it

Freeze plugs blowing out is how the 5.9L's rear cylinder heat problem ends, and this kit stops it before it starts. A secondary thermostat reacts to temperature, so the back of the block gets the coolant flow it's been missing and all six cylinders run at the same temp. It comes complete with braided hose and AN O-ring fittings. PPEI recommends this bypass for any Cummins that works hard, and we run Fleece bypass kits on our own trucks.

Fitment

• Dodge Ram 2500: 2003,2005-2007 Laramie; 2003-2007 SLT, ST; 2006 Sport; 2006-2007 TRX4
• Dodge Ram 3500: 2003-2007 Laramie, SLT, ST; 2006-2007 Sport; 2007 TRX4