Intermittent Hydraulic Valve Adjuster (HVA) Noise. An occasional ticking or rattling noise from the camshaft hydraulic valve lifters (HVA) may occur during cold engine starts, due to frequent short-distance driving, or the noise may occur for an extended period of time even though the engine is at operating temperature. Improved parts were phased into production beginning on 10/1/2008 and fully implemented on November 31st 2008.
