COOLING SYSTEM — 1998.5–2002 DODGE RAM 5.9L CUMMINS (24-VALVE, VP44)

Overheating kills reliability. CPP Diesel curates proven radiators, thermostats (180°/190°), hose kits, fans, coolant bypass systems, reservoirs, pumps, block heaters, and hardware that fit the 1998.5–2002 Ram 2500/3500 5.9L Cummins.

Shop by Subcategory

• Thermostats (180° / 190°) — Cummins 3946849 (190°), Cummins 5292742 (180°), Mishimoto MMTS-RAM-99L/99H.
• Radiators & Caps — CPP Aluminum 3-Row (94–02), Mishimoto MMRAD-RAM-94 (94–02), Radiator Draincock.
• Hoses & Hose Kits — CPP Silicone Coolant Hose Kit (98.5–02).
• Fans & Controllers — CPP Direct-Fit Dual Electric Fans, CPP Dual Fan + Shroud, Mishimoto Fan Accessories.
• Coolant Bypass & Freeze Plug Retention — Fleece 98.5–02 VP44 Bypass Kit, BD Killer Frost Plug Plate.
• Reservoirs & Caps — CPP Coolant Reservoir (94–02), Dorman 603-775.
• Water Pumps & Seals — Cummins 5473238 Pump, CPP Replacement Pump, 3906698 O-ring.
• Block Heaters & Cords — Thread-In Block Heater 3928341, Block Heater Element 3975628.

Featured 98.5–02 Picks

• CPP Aluminum 3-Row Radiator — affordable, TIG-welded, direct-fit (94–02).
• Mishimoto MMRAD-RAM-94 Aluminum Radiator — premium capacity (94–02).
• Cummins 3946849 190° Thermostat or 5292742 180° — OE quality for stable temps.
• CPP Silicone Coolant Hose Kit — molded fit, heat-resistant.
• CPP Direct-Fit Dual Electric Fans — serious airflow with clean mounting.
• Fleece Coolant Bypass (98.5–02 VP44) — balances rear-cylinder temps.
• Coolant Reservoir — fresh tank for an aging 2nd-Gen.

Why Buy from CPP Diesel

• 2nd-Gen Focus: We stock parts that actually fit 1998.5–2002 trucks and call out year-specific details.
• Quality Mix: OE Cummins + Mishimoto/Fleece + CPP-engineered upgrades for durability and performance.
• Expert Support: Thermostat selection, hose routing, fan control, bypass plumbing—done right the first time.
• Fast Shipping: Popular radiators, hose kits, thermostats and pumps ship quickly from U.S. warehouses.

Also see ENGINE PARTS & ACCESSORIES and INTERCOOLERS & BOOST TUBES to complete your build.

Helpful Notes

• Thermostat choice: 190° (OE-like) stabilizes cabin heat & MPG; 180° can help heavy towing or hot climates.
• Bypass benefits: A rear-cylinder coolant bypass equalizes temps on VP44 engines—great for towing or added power.
• Airflow: Clean fins and shrouding matter. Consider a higher-capacity radiator and dual fans if ECT creeps while towing.
• Service basics: Use HOAT/Hybrid OAT coolant compatible with seals; pressure-test and fully bleed after service.
• Winter starts: Pair a block heater element with a thread-in heater/cord for easier cold starts and less engine wear.

Frequently Asked Questions

Should I run a 180° or 190° thermostat on my 24-valve?

For stock or daily-driven trucks, 190° is a great OE-style choice. Heavy tow or hot-climate builds may prefer 180° to keep ECT in check.

Will a coolant bypass help my 98.5–02?

Yes—kits like the Fleece VP44 bypass relieve rear-cylinder pressure and even out temps under load.

Is the Mishimoto radiator a drop-in for 98.5–02?

Yes, the MMRAD-RAM-94 is designed for 94–02 trucks and greatly increases capacity.

Do electric fans replace my mechanical fan?

For street/tow rigs, many use CPP direct-fit dual fans with proper controls; some keep the mechanical fan for extreme towing.

What should I refresh during a cooling overhaul?

At minimum: hoses, thermostat, water pump, clean/upgrade the radiator, and top off with the proper coolant; pressure-test and bleed thoroughly.

Cold weather starts are rough—what helps most?

Combine the block heater element with a thread-in heater/cord for quick, reliable starts and reduced engine wear.