The 2023 Ram 1500's 5.7L Hemi V8 uses Multi-Displacement System (MDS) cylinder deactivation, which can develop a distinctive tick noise. Understanding this system helps determine whether the tick indicates a problem or normal operation.
How Hemi MDS Works
MDS deactivates four cylinders during light-load cruising to improve fuel economy. Special lifters with solenoids collapse to prevent valve operation in deactivated cylinders. The system transitions seamlessly between 4 and 8 cylinder modes.
Causes of MDS Tick
Solenoid Operation Noise
MDS solenoids make slight clicking sounds when activating or deactivating cylinders. This normal operational noise may be noticeable in quiet conditions.
Lifter Wear
MDS lifters have more complex internals than standard lifters, making them prone to wear. Worn lifters may tick continuously rather than just during mode transitions.
Oil Pressure Variations
Lifter operation depends on stable oil pressure. Fluctuations at idle can cause momentary lifter noise as hydraulic pressure varies.
Exhaust Manifold Bolts
The Hemi is known for exhaust manifold bolt breakage, creating tick noises often mistaken for lifter issues. This tick typically increases with temperature.
Distinguishing Normal from Problem Tick
Normal MDS noise is subtle and correlates with cylinder deactivation. Persistent loud tick regardless of MDS mode suggests lifter failure or exhaust manifold issues.