Buy wp20366 - Genuine Cummins Oil Cooler - wisentpartscenter.com

Description

Genuine Cummins 3943657 Oil Cooler is the transmission heat exchanger used on Dodge Ram trucks with the 5.9L Cummins diesel and 47RE automatic transmission. It helps control transmission-fluid temperature by exchanging heat through the engine cooling system, keeping the transmission within a stable operating range during normal driving, towing, and heavy-load operation.

Key Functions
- Transfers heat away from the automatic-transmission fluid.
- Helps keep transmission and torque-converter temperatures under control during load.
- Works with the truck’s transmission cooler circuit to maintain consistent fluid temperature.

Fitment & Specifications
- Vehicle: 1998–2002 Dodge Ram 2500 / 3500
- Engine: Cummins 5.9L diesel
- Transmission: 47RE 4-speed automatic

Verify fitment with us before ordering to ensure the correct part for your application.

Purpose of the Part

The 3943657 helps keep automatic-transmission fluid from becoming excessively hot by passing the transmission fluid through a heat exchanger connected to the engine cooling system. This is especially important when towing, hauling, or operating the truck under conditions that generate additional torque-converter heat.

Issue Symptoms / When to Replace

A leaking or restricted cooler may contribute to elevated transmission temperature, transmission-fluid leaks, or poor cooling performance under load. An internal heat-exchanger failure can also allow transmission fluid and coolant to contaminate one another. Before replacing the cooler for a temperature problem, the cooler lines, front auxiliary cooler, fluid level, and transmission condition should also be checked.

Brand Information

Cummins was founded in Columbus, Indiana in 1919 and has manufactured diesel engines and supporting powertrain components for more than a century. The supplied cooler carries a BEHR factory label; Behr specialized in automotive engine cooling and thermal-management systems and later became part of MAHLE’s Thermal Management business.

Installation Notes

Allow the engine to cool, disconnect the negative battery cable, and drain coolant below the heat-exchanger level before removal. Cap the transmission cooler lines during service to prevent contamination.

How to Identify an OEM Part

A genuine 3943657 can be identified by the factory BEHR manufacturer label.

Why Buy 3943657 from Wisent Parts

  • ⏱️
    Fast shipping
    Orders before 12PM EST ship same business day.
  • 🛡️
    180-day warranty
    All parts covered from delivery date.
  • ↩️
    Easy returns
    30-day returns.
  • ✅
    Verify fitment
    Send VIN/ESN and we’ll confirm.

Shop with confidence

Warranty & Return Information
Warranty Information

Wisent Parts offers a 180-day warranty on all parts from the date of delivery. This warranty covers orders placed directly through our website. If a part fails during this period, we’re here to help - whether it’s a replacement, repair, or refund. For full details, refer to the Warranty page.

Return Information

Wisent Parts accepts returns within 30 days of delivery. All returns are subject to a restocking fee. To qualify, parts must be unused and in their original condition. For full return instructions and restocking fee details, please refer to the Returns page.