Fleece Coolant Bypass VP (FPE-CLNTBYPS-CUMMINS-VP) for 1998.5-2002 Cummins 5.9L
$376.95
The Fleece Coolant Bypass VP (FPE-CLNTBYPS-CUMMINS-VP) is an aftermarket kit for 1998.5–2002 Cummins 5.9L diesel engines that improves coolant flow to the rear cylinders—a common weak point in the stock system. It helps reduce pressure spikes, stabilize engine temperatures, and prevent head gasket failures, especially in high-performance or heavy-duty use. Built with durable components, it offers a reliable, leak-free installation and enhances engine longevity and performance.
The Fleece Coolant Bypass VP (FPE-CLNTBYPS-CUMMINS-VP) is a high-quality aftermarket solution designed specifically for the 1998.5–2002 Cummins 5.9L diesel engines. This coolant bypass kit addresses a common weak point in the factory cooling system by improving coolant flow to the rear cylinders, which are often underserved in stock configurations. By providing more balanced coolant distribution, the Fleece coolant bypass helps reduce coolant pressure spikes, stabilize engine temperatures, and prevent potential head gasket failures—especially in high-performance or heavy-duty applications. Built with durability in mind, this kit includes premium fittings and hoses for a reliable and leak-free installation, making it a smart upgrade for Cummins owners looking to enhance the longevity and performance of their engine.
| Weight | 15 lbs |
|---|---|
| Dimensions | 12 × 9 × 4 in |
Fitment
- 1998.5 Dodge Ram 2500/3500 5.9L VP 24V Cummins
- 1999 Dodge Ram 2500/3500 5.9L VP 24V Cummins
- 2000 Dodge Ram 2500/3500 5.9L VP 24V Cummins
- 2001 Dodge Ram 2500/3500 5.9L VP 24V Cummins
- 2002 Dodge Ram 2500/3500 5.9L VP 24V Cummins
Features
Increased Coolant Flow, Decreased Coolant Temperatures
The rear cylinders on the 5.9/6.7L Cummins suffer from a lack of coolant flow, and therefore, experience the highest coolant temperatures. This can cause excessive pressure to build in the cooling system, especially the rear of the block and blow out freeze plugs externally, or the smaller diameter plugs under the valve cover, leading to a failure. Our coolant bypass kit adds 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.
Benefits:
- Lowers coolant temperature at the rear cylinders
- Ensures consistent temperatures across all cylinders
- Prevents damaging coolant pressure build up
- Complete kit comes with braided hose and AN O-ring fittings to ensure a leak-free installation. Kits for MY 2003+ include billet hose brackets.
Why do I need a Fleece Performance Coolant Bypass?
One of the biggest issues on the 5.9/6.7L Cummins is the coolant flow problem to the rear cylinders. This can cause catastrophic failure or blow outs of the freeze plugs in an over-temperature / over-pressure condition. The Fleece Performance Coolant Bypass is one of the most important additions you make to improve the reliability and longevity of the Cummins platform.
*US Trademark Reg. No. 6099979, 6099980, 6099981 and 7659022.
Application Notes
The 2003 – 2007 5.9L automatic transmission version will eliminate the factory transmission fluid heat exchanger. The heat exchanger is 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.
For model years 2007 – 2018 6.7L trucks, including both automatic and manual equipped transmissions, factory installed transmission fluid heat exchangers are uncommon. For customers with a 6.7L that has a heat exchanger, a heater tube can be purchased at your local Chrysler Dealership [PN:68048997AA] to complete the installation.
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