Cummins 3957544 — Genuine Engine Oil Cooler Core for 5.9L (6BT/ISB)

MPN: 3957544  |  Also Known As: oil cooler core, stacked-plate oil cooler  |  Cross-Refs (ID only): 3921558 (Cummins), 4713985AB (Mopar)

Genuine Cummins stacked-plate oil cooler designed to regulate oil temperature and protect bearings, cam, and turbo on 1989–2002 5.9L 12-valve & 24-valve (VP44) trucks. Direct-fit OEM quality. Sold individually (1 per engine).

Features & Benefits

• OE heat rejection for stable viscosity and oil pressure under load.
• Direct-fit replacement for 5.9L 6BT/ISB non-common-rail applications.
• Stacked-plate core construction for efficient thermal transfer.
• Helps prevent bearing/turbo damage from overheated or contaminated oil.
• Built to Cummins standards for fit, function, and durability.

Verified Fitment (Automotive)

Industrial/Off-Highway: 4BT/6BT/ISB5.9 variants (BS3 era). Verify by ESN before ordering.

Specifications

• Type: Engine oil cooler core (stacked-plate)
• OE Part Number: 3957544
• Cross-References (ID): 3921558 (Cummins), 4713985AB (Mopar)
• Quantity Required: 1 per engine (sold individually)

Often Paired With

• Cooler-to-filter gasket (’89–’96): 3929792
• Cooler-to-filter gasket (’97–’02): 3942915
• Cooler-to-block gasket (’89–’02): 4932124
• Fresh oil & filter: change after cooler replacement to flush debris

What’s In The Box

• (1) Genuine Cummins Oil Cooler Core (3957544)
• Gaskets/hardware sold separately (see “Often Paired With”).

Installation Tips

• Inspect/flush the lubrication circuit after any internal failure before installing the new cooler.
• Use new gaskets and torque fasteners to factory spec; check for leaks on warm-up.
• Change engine oil & filter after installation and again after initial heat cycle if contamination was present.

FAQ

WILL THIS FIT MY 1989–2002 5.9L CUMMINS RAM?

Yes—3957544 is the OE cooler core for 1989–2002 5.9L (12V & 24V VP44) Ram 2500/3500. Confirm by VIN/ESN.

DOES THIS COME WITH GASKETS?

No—gaskets are sold separately. Typical pairings: 3929792 (’89–’96 cooler-to-filter), 3942915 (’97–’02 cooler-to-filter), and 4932124 (’89–’02 cooler-to-block).

WHAT ABOUT 2003+ TRUCKS?

Common-rail applications use later coolers; verify your year/engine and order the correct part for 2003–2007 5.9L or 2007.5+ 6.7L.

HOW DO I KNOW MY COOLER IS FAILING?

Low oil pressure, overheating, or oil/coolant cross-contamination are common symptoms. Replace promptly to prevent engine damage.

IS THIS A GENUINE CUMMINS PART?

Yes—OE Cummins part 3957544 for proper fit and durability.