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Cummins Coolant Bypass Kit Auto Trans 2003-2005 Dodge Ram 2500/3500 5.9 Cummins Fleece Performance
SKU: FPE-CLNTBYPS-CUMMINS-0305-FQWW
Protect your 5.9L or 6.7L Cummins with the Fleece Performance Coolant Bypass Kit—engineered for lower coolant temps, consistent cylinder cooling, and maximum diesel reliability.
Vehicle Specific
Check if this part fits your vehicle.
Solve one of the most critical cooling issues on your 5.9L or 6.7L Cummins with the Fleece Performance Coolant Bypass Kit. The rear cylinders on these engines are notorious for running hotter due to poor coolant flow, leading to excessive pressure, blown freeze plugs, and even catastrophic engine failures—especially in high horsepower or towing applications.
Fleece’s coolant bypass kit adds a secondary thermostat that activates based on temperature (not just pressure), ensuring even cooling across all six cylinders and preventing dangerous pressure spikes before they start. This kit is a must-have upgrade for diesel truck owners seeking reliability, lower EGTs, and long-term engine health. Each kit includes braided hose, AN O-ring fittings for a leak-free install, and billet hose brackets for 2003+ models. If you own an ‘03–‘07 5.9L automatic, this kit also eliminates the stock transmission fluid heat exchanger—ideal for performance builds and warm climates.
Upgrade your Cummins with this proven diesel performance solution and keep your engine running cooler, longer, and stronger—no matter how hard you push it.
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.
- Engine Year2003-2005
- 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.