General Motors has released a new service bulletin, PIP6101, detailing the cause and repair procedure for a characteristic top-end ticking sound in four-cylinder turbo engines installed in some 2025-2026 Chevrolet Silverado 1500, Colorado, and Traverse models.

The issue affects the 2.7 L3B engine (Silverado, Colorado) and the 2.5 LK0 engine (Traverse). GM states the source is manufacturing debris in the stationary hydraulic lash adjuster (SHLA), which prevents the component from maintaining oil pressure. This "soft" adjuster creates a ticking noise in the upper part of the valve train.

Technicians are instructed to confirm the sound source using a stethoscope, then remove the camshaft block and manually check the firmness of each hydraulic lash adjuster through the pushrod or rocker arm on the intake and exhaust sides. Any "soft" components must be replaced along with the corresponding rocker arm. All parts are selected from the GM catalog.

The company emphasizes that the bulletin is intended for professional service centers and does not mean all vehicles of these models will necessarily encounter this defect. In practice, this is a typical example of a subtle factory issue that surfaces in real-world use—and it highlights how GM aims to structure diagnostics for dealers as thoroughly as possible.