CUMMINS 3918428 OEM ENGINE OIL PRESSURE REGULATOR PLUNGER – RAM 5.9L 12-VALVE (1994–1998)

Product Description

The Cummins 3918428 OEM Engine Oil Pressure Regulator Plunger is the genuine factory plunger used inside the oil pressure relief and regulation assembly of the 1994–1998 5.9L 12-Valve Cummins 6BT. This precision-machined component maintains correct system oil pressure by controlling bypass flow inside the lubrication circuit. Using a genuine Cummins regulator plunger ensures proper sealing, smooth movement, and long-term reliability—critical for engine longevity and stability under load.

If you’re rebuilding your 12-valve, repairing low oil pressure, or restoring an OEM oil pump assembly, the 3918428 plunger is the correct replacement part for accurate pressure regulation and factory-spec performance.

Fitment

• 1994–1998 Dodge Ram 2500/3500 with 5.9L 12-Valve Cummins (6BT)
• 5.9L B-Series engines using the OEM oil pump/pressure relief assembly with plunger-style regulator

Note: Some B-Series industrial/off-highway variants also use this plunger. For these applications, verify by ESN.

Cross-Reference (Cummins-Only)

Related 12-valve lubrication and hardware components:
• Cummins 3915787 Threaded Plug – Oil Pressure Relief
• Cummins 3900625 Hex Flange Head Cap Screw
• Cummins 3900267 Tappet Cover Bolt Grommet Seal

FAQ

What does the Cummins 3918428 regulator plunger do?

The plunger controls oil pressure by regulating relief flow inside the oil pump/pressure relief system.

Are low oil pressure symptoms related to this plunger?

Yes. A worn or sticking plunger can cause inconsistent or low oil pressure, especially when hot.

Does this part fit 24-valve ISB engines?

No. This plunger is specific to the 12-valve 5.9L 6BT (1994–1998). ISB engines use different regulation hardware.

Should I replace the spring along with the plunger?

Often yes. Weak or fatigued springs affect regulation. Replace the plunger and spring together for best results.

Specifications for cummins 3918428