COOLING SYSTEM
COOLING SYSTEM — 03–07 DODGE RAM 5.9L CUMMINS
Fitment: 2003–2007 Dodge/Ram 2500 & 3500 with 5.9L 24-valve common-rail Cummins. Keep ECTs stable while towing, daily driving, or sled-pulling with proven radiators, thermostats, water pumps, fan clutches, hoses, and coolant bypass solutions from CPP Diesel.
Popular Upgrades & Service Parts
- Radiators
Mishimoto Aluminum Performance Radiator (R2711-MT)
CSF 3710 OE-Replacement Radiator - Thermostats
Cummins 5292744 — 190°F OEM Thermostat
Cummins 5292742 — 180°F Thermostat (performance/towing)
Thermostat Category (including Mopar 05086739AB) - Water Pumps
Cummins 5473238 Genuine Water Pump
All Water Pumps - Fan Clutch & Controls
CPP 55056990AC Electronic Cooling Fan Clutch
Fan Clutch Connector Pigtail (68052582AB) - Hoses & Heater Lines
Dayco 72241 Lower Radiator Hose
Fleece Heater Core Replacement Hose & Fitting (FPE-CUMM-HCL-0324) - Coolant Bypass & Heat Exchanger Solutions
Fleece Coolant Bypass Kit — 2003–2005 Auto
Fleece Coolant Bypass Kit — 2006–2007 Auto
Fleece Coolant Bypass Kit — 2003–2007 Manual
Heat Exchanger Bypass Plug Kit (FPE-34382) - Sensors & Monitoring
Coolant Temperature Sensor (M-4954905)
Engine Parts (Thermostat, Oil Cooler, etc.) - Block/Frost Plug Solutions
Cummins 3928341 Thread-In Block Heater (category list)
BD “Killer” Rear Frost Plug Plate
CPP Common Rail Expansion Plug Kit
Why Upgrade Your 5.9L Cooling System?
- Towing & Workloads: Larger-core radiators and healthy fan control keep temps in check on long grades.
- Longevity: Fresh water pump, correct-temp thermostat, and quality hoses reduce hotspots and pressure spikes.
- Consistency: Coolant bypass kits stabilize rear-cylinder temps—great for tuned and hard-working trucks.
Frequently Asked Questions
Which thermostat temp should I choose?
Most stock trucks do well with the 190°F OEM thermostat. If you tow heavy or run performance tunes, the 180°F option can help smooth temperature swings.
Do I need a coolant bypass kit?
It’s a popular reliability mod on 5.9L trucks to equalize temps at the rear cylinders. Choose the kit matched to your model year and transmission: 03–05 Auto, 06–07 Auto, 03–07 Manual.
My fan clutch is acting up—what should I check?
The electronic fan clutches on these trucks fail with heat and age. Replace the clutch (CPP 55056990AC) and fix damaged wiring with the correct connector pigtail.
Which coolant should I run?
Use a high-quality antifreeze that meets OEM specifications for your model year and climate. Many owners use HOAT/G-05 type coolant—always verify with your owner’s manual.
What are common water pump failure signs?
Coolant weep at the pump, bearing noise, or temperature creep at idle/light load. If present, replace with a genuine Cummins pump.
Cold-weather starting tips?
A thread-in block heater helps winter starts and warm-up. See the 03–07 engine parts list for the 3928341 block heater and cord.
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FLEECE FPE-CLNTBYPS-CUMMINS-0305-SS CUMMINS COOLANT BYPASS KIT 003-05 AUTO TRANS WITH STAINLESS STEEL BRAIDED LINE
FLEECE PERFORMANCE ENGINEERING
$359.00Increased 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...$359.00 -
FLEECE FPE-CLNTBYPS-CUMMINS-MAN-SS CUMMINS COOLANT BYPASS KIT 03-07 MANUAL TRANSMISSION W/ STAINLESS STEEL BRAIDED LINE
FLEECE PERFORMANCE ENGINEERING
$359.00Increased 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...$359.00 -
FLEECE FPE-CLNTBYPS-CUMMINS-0607-SS CUMMINS COOLANT BYPASS KIT 06-07 AUTO TRANS WITH STAINLESS STEEL BRAIDED LINE
FLEECE PERFORMANCE ENGINEERING
$359.00Increased 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...$359.00 -
FLEECE FPE-CLNTBYPS-CUMMINS-0305 CUMMINS COOLANT BYPASS KIT 2003-2005 AUTO TRANS
FLEECE PERFORMANCE ENGINEERING
$359.00Increased 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...$359.00 -
FLEECE FPE-CLNTBYPS-CUMMINS-MAN CUMMINS COOLANT BYPASS KIT 2003-2007 MANUAL TRANSMISSION
FLEECE PERFORMANCE ENGINEERING
$359.00Increased 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...$359.00 -
FLEECE FPE-CLNTBYPS-CUMMINS-0607 CUMMINS COOLANT BYPASS KIT 2006-2007 AUTO TRANS
FLEECE PERFORMANCE ENGINEERING
$359.00Increased 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...$359.00 -
CPP 55056990AC COOLING FAN CLUTCH FOR 2004-2010 DODGE RAM WITH 5.9L/6.7L CUMMINS ENGINE
CPP DIESEL
$379.95The CPP 55056990AC Cooling Fan Clutch stands out as a crucial replacement component for owners of 2004-2010 Dodge Ram trucks featuring the robust 5.9L or 6.7L Cummins engine. This precision-engineered part, developed by CPP, a trusted leader in the...$379.95 -
INDUSTRIAL INJECTION 24FC09 DODGE COMMON RAIL PULLEY KIT FOR 03-12 CUMMINS
INDUSTRIAL INJECTION
$286.11The Industrial Injection Billet Pulley Kit is designed to add a little bling to your 2003-2012 Cummins engine. These pulleys have been tested up to 5500rpm and 2000hp and performed flawlessly. Kit includes Billet Fan Pulley and 4.5 inch Billet Idler...$286.11 -
MOPAR 05086739AB 190 DEGREE COOLANT THERMOSTAT FOR 03-07 DODGE WITH 5.9L CUMMINS ENGINE
MOPAR
$309.36The Mopar 05086739AB 190 Degree Coolant Thermostat is a precision-engineered component designed specifically for 2003-2007 Dodge trucks with 5.9L Cummins engines. Crafted by Mopar, a trusted name in automotive parts, this thermostat ensures optimal...$309.36 -
MOPAR 5003619AB ENGINE BLOCK HEATER FOR 98.5-18 DODGE RAM WITH 5.9L/6.7L CUMMINS ENGINE
MOPAR
$223.36The Mopar 5003619AB Engine Block Heater is an essential accessory for Dodge Ram trucks equipped with the robust 5.9L or 6.7L Cummins engines, applicable from 1998.5 to 2018 models. Designed with precision and high standards that are synonymous with the...$223.36 -
MOPAR 52028878AB ENGINE COOLING FAN FOR 03-09 DODGE RAM WITH 5.9L/6.7L CUMMINS ENGINE
MOPAR
$292.11Enhance the reliability and efficiency of your Dodge Ram with the Mopar 52028878AB Engine Cooling Fan, specifically designed for the 2003-2009 models featuring the mighty 5.9L and 6.7L Cummins engines. This top-tier cooling fan is integral to maintaining...$292.11 -
DORMAN 622-104 COOLING FAN CLUTCH 2004-2010 DODGE RAM 5.9L/6.7L DIESEL
DORMAN
$298.41The DORMAN 622-104 Cooling Fan Clutch for 2004-2010 Dodge Ram 5.9L/6.7L Diesel engines is an exceptional replacement part designed to keep your vehicle's cooling system running efficiently. This high-quality fan clutch is specifically engineered to fit...$298.41 -
DORMAN 300-809 ENGINE COOLING FAN PULLEY BRACKET 2003-2012 DODGE 5.9L/6.7L DIESEL
DORMAN
$242.81Crafted with precision and quality in mind, the DORMAN 300-809 Engine Cooling Fan Pulley Bracket for 2003-2012 Dodge 5.9L/6.7L Diesel vehicles is the perfect replacement part to ensure optimal engine cooling performance. Designed to seamlessly match the...$242.81 -
CPP DIESEL DIY REMOTE COOLANT TANK KIT FOR 1994-2009 DODGE CUMMINS ENGINES
CPP DIESEL
$299.95The CPP Diesel DIY Remote Coolant Tank Kit is the ultimate upgrade for 1994-2009 Dodge Cummins 5.9L/6.7L 12V/24V engines, meticulously designed to transform your engine bay into a masterpiece of performance and style. Crafted from durable aluminum, the...$299.95 -
MISHIMOTO R2711-MT REPLACEMENT RADIATOR 2003-2009 CUMMINS 5.9L/6.7L
MISHIMOTO
$335.95The MISHIMOTO R2711-MT Replacement Radiator for the 2003-2009 Cummins 5.9L/6.7L is the ultimate solution for Dodge Ram 2500/3500 owners looking to replace their aging or faulty factory radiators. Designed as a direct OEM replacement, this radiator...$335.95 -
MISHIMOTO MMHOSE-RAM-03DRD DIESEL HOSE KIT - RED 2003-2010 CUMMINS 5.9L/6.7L
MISHIMOTO
$357.95Enhance the performance and durability of your 2003-2010 Dodge Ram 5.9L/6.7L Cummins engine with the Mishimoto MMHOSE-RAM-03DRD Diesel Hose Kit in striking red. Engineered as an ideal replacement for factory rubber coolant hoses, Mishimoto's silicone...$357.95 -
MISHIMOTO MMHOSE-RAM-03DBL DIESEL HOSE KIT - BLUE 2003-2010 CUMMINS 5.9L/6.7L
MISHIMOTO
$357.95Mishimoto presents the ultimate solution for enhancing your Cummins engine's performance with the MISHIMOTO MMHOSE-RAM-03DBL Diesel Hose Kit in blue, designed for the 2003-2010 Cummins 5.9L/6.7L engines. Say goodbye to the limitations of factory rubber...$357.95 -
MISHIMOTO MMFAN-16HD Race Line High-Flow Fan 16 inch Black
MISHIMOTO
$220.95Enhance the cooling capabilities of your radiator with the MISHIMOTO MMFAN-16HD Race Line High-Flow Fan in a sleek black finish. Engineered for heavy-duty applications that demand superior performance, this 16-inch fan from our Race Line series delivers...$220.95 -
CUMMINS 3910739 | GENUINE OEM BALL BEARING-FAN HUB | FITS 1989-2018 DODGE RAM 5.9L & 6.7L CUMMINS
CUMMINS
$250.95CUMMINS 3910739 | GENUINE OEM BALL BEARING-FAN HUB | FITS 1989-2018 DODGE RAM 5.9L & 6.7L CUMMINS The Cummins 3910739 GENUINE OEM BALL BEARING-FAN HUB is a genuine OEM replacement designed for Dodge Ram Cummins trucks. Function & Purpose Engineered...$250.95 -
CPP BILLET ELECTRIC WATER PUMP FOR 1989-2018 CUMMINS 5.9L/6.7L 12V/24V
CPP DIESEL
$349.95Enhance the performance of your Cummins diesel engine with the CPP Diesel Competition Cummins 5.9L/6.7L Billet Electric Water Pump, designed for 1989-2018 Dodge Cummins 5.9L/6.7L 12V/24V engines. This premium aftermarket water pump is the ideal choice...$349.95 -
CUMMINS 5473238 OEM WATER PUMP KIT – 5.9L/6.7L (1989–2012)
CUMMINS
$366.22Cummins 5473238 — Genuine Water Pump Kit for 5.9L & 6.7L ISB MPN: 5473238 | Also Known As: engine water pump, water pump kit | Supersedes / Cross-Refs (ID): 2881804, 2881805, 3286278, 68003402AA, 4955359 Restore OE...$366.22