4930315 Thermostat for Cummins 4BTA 6B 6BT 6BTA Replace No. 3972071 3911724

The Cummins 4930315 Thermostat is a genuine OEM replacement for multiple Cummins B-series engines, superseding older part numbers 3972071 and 3911724. Here’s a detailed breakdown:

Key Specifications

• Temperature Rating: 83°C (181°F) opening, full open at 95°C (203°F)

• Housing Material: Brass/bronze (corrosion-resistant)

• Seal Type: Integrated rubber gasket

• Bypass Design: Balanced flow for rapid warm-up

Compatible Engines

✔ 4BTA 3.9L (Turbo + Aftercooled)
✔ 6B 5.9L (Naturally Aspirated)
✔ 6BT 5.9L (Turbocharged – Dodge Ram 12V 1989-1998)
✔ 6BTA 5.9L (Turbo + Aftercooled – Marine/Industrial)

Replaces Obsolete Parts

• 3972071 (1980s-90s design)

• 3911724 (early brass variant)

Critical Installation Notes

1. Orientation:

   • “Cummins” stamp faces outward

   • Jiggle valve at 12 o’clock position

2. Torque:

   • Housing bolts: 24 Nm (18 lb-ft)

   • Use anaerobic sealant (Loctite 518) on gasket surface

3. System Prep:

   • Always flush coolant passages before installation

   • Use 50/50 OAT coolant (e.g., Fleetguard ES Compleat)

Cross-Reference

Warning

⚠ Failure Risks if Incorrect:

• Overheating (stuck closed)

• Extended warm-up (stuck open)

• Cavitation damage from improper bypass flow

Performance Verification

1. Bench Test:

   • Should begin opening at 181°F in water bath

   • Fully open by 203°F with ≥10mm lift

2. Field Check:

   • Upper radiator hose should stay cool until reaching operating temp

   • No coolant flow to radiator below 180°F