Leak-Free Rear Welsh (Freeze) Plug for 4BT & 6BT Cummins

The factory rear welsh plug is a common failure point on Cummins engines, especially in high-performance, towing, and heavy-duty applications. Increased boost and cylinder pressures can cause factory plugs to leak or blow out, leading to coolant loss, downtime, and expensive repairs.

The EPC Leak-Free Rear Welsh (Freeze) Plug is engineered to provide a permanent solution. Precision-machined from billet material and supplied with premium sealing components, it delivers superior strength, reliability, and serviceability compared to the factory design.

Vehicle Compatibility

✔ 4BT Cummins
✔ 6BT 12 Valve Cummins

Only one rear plug is required per engine.

Why Choose the EPC Rear Welsh Plug?

✅ Billet Construction
Precision-machined for exceptional strength and long-term durability.

✅ Leak-Free Sealing System
Utilises a high-temperature Viton O-ring to ensure a reliable seal under extreme conditions.

✅ Built for High-Boost Applications
Designed to withstand the cylinder pressures and cooling system demands that commonly cause factory plugs to fail.

✅ Corrosion-Resistant Components
Supplied with stainless steel hardware for maximum corrosion resistance and service life.

✅ Added M8 threads for EPC solid heater lines (ETA August 2026)

✅ Integrated pilot dimple to aid in installing sensors.
We added a pilot dimple for those wanting to use the rear plug for sensors or a coolant bypass. Simply drill and tap to accomodate any threads you need.

What's Included?

• Billet Leak-Free Rear Welsh (Freeze) Plug

• High-Temperature Viton O-Ring

• Stainless Steel Fastening Hardware

Whether you're building a competition truck, tow rig, or reliable street-driven Cummins, the EPC Leak-Free Rear Welsh Plug provides peace of mind where it matters most.

Leak-Free for Life.

Recommended product page callout:

⚠️ This listing is for the REAR Welsh (Freeze) Plug only. One plug is required per engine.