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  • DODGE CUMMINS
  • FORD POWERSTROKE
  • GM DURAMAX
  • COMMERCIAL / INDUSTRIAL
  • CUMMINS CONVERSION PARTS
  • CPP GEAR
  • USED PARTS
  • SHOP BY BRAND

    • Shop by Brand

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    • COOLING SYSTEM

    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.

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    Featured 98.5–02 Picks

    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.

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