5.9 Cummins 12V Loaded O-Ring Cylinder Head | DK Engines DK-CU5.9-12VCHLO

Restore reliability and performance to your 1989–1998 5.9L 12-Valve Cummins with this premium Loaded O-Ring Cylinder Head from DK Engine Parts. This is a brand-new casting (not remanufactured) that arrives fully assembled and ready to bolt on — no core charge and no machine shop required.

The standout feature is the precision-machined O-ring groove on the fire deck. This design dramatically improves head gasket sealing by biting into the fire ring of the gasket, helping keep combustion pressure in the cylinder and out of the cooling system. It’s an excellent upgrade for high-mileage trucks, towing applications, or any build seeing boost.

Fully Loaded with New Components:

• All-new intake and exhaust valves with black nitride coating for superior heat and wear resistance
• New valve springs, retainers, locks, and stem seals
• New valve seats and guides
• Precision valve job for excellent sealing and airflow

Key Benefits:

• Superior head gasket retention compared to a stock or non-O-ringed head
• Reduced risk of blown head gaskets under load
• Ideal for stock rebuilds or mild performance/towing builds
• Works best with Multi-Layer Steel (MLS) head gaskets (recommended, sold separately)
• No core charge — brand new casting

Fitment:

• 1989–1998 Dodge Ram 2500/3500 with 5.9L 12-Valve Cummins (both VE pump and P7100 models)
• For use with 7mm injectors
• Direct replacement for OE #3925400

Specifications:

• Brand: DK Engine Parts
• Type: Brand new casting, fully loaded & O-ringed
• Warranty: 1-Year Limited Warranty
• Shipping: Truck freight (heavy item)

This head gives you a complete top-end refresh without the hassle and expense of machining an old head. Whether you’re doing a reliability refresh or building a strong towing rig, the DK-CU5.9-12VCHLO delivers a solid foundation for your 12-Valve Cummins.