Dave Hilux 2007 Workmate

For the past two to three weeks, I have had a rattling noise coming from what seems the front right side under the bonnet. It occurs everytime I put my foot off the accelerator. The sound is like a rattle and lasts for a second or two. At around 58 to 60km per hour, the sound can continue for longer. My mechanic does not know what it is. He just changed the clutch and noise still evident. Is this a common issue? Driving me crazy.