GMC, timing diagnostics in Zevulun

GMC, timing diagnostics in Zevulun.
A timing belt or a timing chain requires diagnostics in the following cases: reduced engine power, metallic knocking in the cylinder head, camshaft drive noise, blue exhaust smoke, and malfunctions of a "cold" engine. The timing diagnostics includes visual inspection, determining the phases of the car's valve train, measuring the thermal gap between the valve and the rocker actuator, measuring the gap between the valve and the seat.