5.9 24V Cummins Fleece Coolant Bypass Kit

Thumbnail Filmstrip of 5.9 24V Cummins Coolant Bypass Kit Fleece FPE-CLNTBYPS-CUMMINS-VP Images

Fleece Performance Coolant Bypass Kit for 1998.5-2002 5.9L 24V Cummins (VP44) Part #: FPE-CLNTBYPS-CUMMINS-VP (Black Nylon Braided Hose)

Stop Rear Cylinder Overheating & Blown Freeze Plugs on Your 24V Cummins

The factory cooling system on 1998.5-2002 Dodge Ram 5.9L 24V Cummins engines (VP44) was designed around stock power levels. The rear cylinders receive significantly less coolant flow than the front, causing them to run much hotter. This temperature imbalance creates excessive pressure in the cooling system — often resulting in blown freeze plugs (both the large external plugs and the smaller ones under the valve cover).

Whether your truck is stock or modified with tuning, injectors, or a performance turbo, this is one of the most important reliability upgrades you can make to a 2nd Gen 24V Cummins.

Fleece Performance Temperature-Based Solution

The Fleece Coolant Bypass Kit (FPE-CLNTBYPS-CUMMINS-VP) adds a secondary thermostat that opens based on actual coolant temperature — not pressure like cheaper competitor kits. This proactive design increases coolant flow to the rear of the engine, equalizes temperatures across all six cylinders, and prevents pressure from building to dangerous levels in the first place.

Key Benefits

Dramatically lowers coolant temperatures at the critical rear cylinders
Provides consistent cooling across the entire engine
Prevents excessive cooling system pressure and blown freeze plugs
Increases overall coolant circulation and engine longevity
Essential upgrade for any modified or high-horsepower 24V Cummins
Clean, professional installation with no permanent modifications

Premium Kit Contents

Temperature-controlled secondary thermostat assembly
High-quality black nylon braided coolant hose
AN O-ring fittings for a leak-free connection
All necessary mounting hardware

Vehicle Fitment

1998.5 – 2002 Dodge Ram 2500 & 3500
5.9L Cummins 24V (VP44 injection pump)
Works with both automatic and manual transmissions

Why Fleece? Fleece Performance designs real-world solutions based on common Cummins failures. This kit is widely regarded by diesel builders and enthusiasts as a must-have reliability mod for any serious 24V build.

Installation Straightforward DIY install with basic hand tools (no cab removal required). Full instructions are available below. Most customers complete the job in a few hours.

Fleece Performance Coolant Bypass Kit for 1998.5-2002 5.9L 24V Cummins (VP44) Part #: FPE-CLNTBYPS-CUMMINS-VP (Black Nylon Braided Hose)
Stop Rear Cylinder Overheating & Blown Freeze Plugs on Your 24V Cummins
The factory cooling system on 1998.5-2002 Dodge Ram 5.9L 24V Cummins engines (VP44) was designed around stock power levels. The rear cylinders receive significantly less coolant flow than the front, causing them to run much hotter. This temperature imbalance creates excessive pressure in the cooling system — often resulting in blown freeze plugs (both the large external plugs and the smaller ones under the valve cover).
Whether your truck is stock or modified with tuning, injectors, or a performance turbo, this is one of the most important reliability upgrades you can make to a 2nd Gen 24V Cummins.
Fleece Performance Temperature-Based Solution
The Fleece Coolant Bypass Kit (FPE-CLNTBYPS-CUMMINS-VP) adds a secondary thermostat that opens based on actual coolant temperature — not pressure like cheaper competitor kits. This proactive design increases coolant flow to the rear of the engine, equalizes temperatures across all six cylinders, and prevents pressu[...]