Can someone help me out with this problem, have a vectra with a fairly loud tapping noise when accelerating, you start up and it taps, wait for a few mins and it stops at idle, soon as you apply throttle it sounds like the tappets are going spastic. But have been inforded that its the manafold gasket gone or something on the related area. Have tried wynnes engine flush to clean a possible sticking valves, but no joy. Now vaux have said it will cost about £600 to change the gasket cos you can be sure the studs will snap and will need redrilling, even with a gas gun. Can anyone please advise.