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Cummins Coolant Bypass Kit Manual Transmission 2003-2007 Dodge Ram 250/3500 5.9 Cummins Fleece Performance
SKU: FPE-CLNTBYPS-CUMMINS-MAN-FQWW
Upgrade your 2003–2007 Dodge/Ram 5.9L Cummins manual with the Fleece Performance Coolant Bypass Kit—engineered for lower rear cylinder temps, balanced cooling, and long-term diesel reliability.
Vehicle Specific
Check if this part fits your vehicle.
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.
Protect your 2003–2007 Dodge/Ram 2500/3500 5.9L Cummins (manual transmission) from overheating and pressure-related failures with the Fleece Performance Coolant Bypass Kit. The rear cylinders on the 5.9L Cummins are known for poor coolant flow, leading to higher temps, excessive system pressure, and the risk of blown freeze plugs—especially in high horsepower, towing, or heavy-use trucks.
This kit features a secondary thermostat that activates based on coolant temperature, not just pressure, ensuring even cooling across all six cylinders and preventing dangerous pressure spikes before they start. The complete kit includes premium braided hose, AN O-ring fittings for a leak-free install, and billet hose brackets for a secure, professional fit.
The Fleece Coolant Bypass Kit is a must-have upgrade for any diesel owner looking to safeguard their 5.9L Cummins, boost reliability, and keep their truck running strong under any load or conditions.
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 and up include billet hose brackets.
Why do I need a Fleece 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 Coolant Bypass is one of the most important additions you make to improve the reliability and longevity of the Cummins platform.
The 03-07 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 07-13 6.7 trucks, both automatic and manual equipped transmissions, do not have a transmission fluid heat exchanger.
- Engine Year2003-2007
- Vehicle TypeTruck/SUV
- Property 65 WarningCALIFORNIA WARNING: Cancer and Reproductive Harm -www.P65Warnings.ca.gov
- BrandFleece Performance
- Country of OriginUSA
- Sold AsKit
Shipping Times
Most customers will see their parts within 3-5 business days. We will primarily ship with Purolator ground & DHL Express to ensure the fastest shipping possible.
Please Note: These are only estimates and shipping time may vary depending on your location, out of country and rural locations expect longer wait times.
Where Do We Ship
We will ship our products within Canada and the United States.
Please Note: There are limitations what can be shipped to the United States.
Damaged Shipments
We provide the option to purchase insurance as we are not responsible for any damage while with a courier, we don’t often see issues, but it does happen. If you purchased insurance we will put in a claim, if no insurance was purchased there will be no refunds or exchanges.
Return Policy
It happens sometimes we would like to return it. Here are our return rules:
- Prior to any return you must contact us and get an approval for a RMA number.
- Product must be unopened and have no damage.
- You must pay for the shipping back, please insure so if anything happens you can make a claim, we are not responsible for damage during shipping and is the sole responsibility of the customer.
- Regular products are subject to a 5% Restocking fee.
- Items over 50 lbs. or special orders will be subject to a 20% Restocking fee.
- Electronics & Tuning is a final sale and cannot be returned.