2018 Ram 1500 Hemi Tick - Lifter or MDS issue?

ClearTheCode admin answer:

The 'Hemi tick' is a well-known issue that can indeed be caused by a few different factors, most commonly related to the Multi-Displacement System (MDS) lifters or exhaust manifold leaks.

Common Causes & Diagnostics:

1. MDS Lifter Failure: This is the most serious and common cause. The MDS system deactivates cylinders for fuel economy. The lifters designed for MDS can fail, leading to excessive play and wear on the camshaft lobe. This often results in a distinct ticking or tapping sound that can worsen over time.
   • Diagnostics: A mechanic can use a stethoscope to pinpoint the noise. If a misfire is present, you might see codes like P0301-P0308 (Cylinder Misfire Detected). A compression test or bore scope inspection might be needed to confirm lifter/cam damage.
2. Exhaust Manifold Leak: A much less severe cause, but can sound similar. The exhaust manifold bolts can break or loosen, creating a small leak that produces a ticking sound, especially when cold, which might lessen as the engine warms and metal expands.
   • Diagnostics: Visually inspect manifold bolts for breakage or rust. Listen for the sound to change with engine temperature.
3. Oil Viscosity/Level: Using the incorrect oil viscosity or having low oil levels can exacerbate lifter noise. Ensure you're using the manufacturer-recommended oil (typically 5W-20 for the 5.7L Hemi) and that the level is correct.

When to See a Shop:

• If the ticking is consistent, loud, and doesn't go away, especially if accompanied by a check engine light or performance issues, it's crucial to have it inspected by a qualified mechanic immediately. Ignoring a failing MDS lifter can lead to significant engine damage, including camshaft wear and potential metal debris in the oil system. Early diagnosis can prevent more costly repairs.