Timing chain or valve clearance?

[SteveJones]

I'm getting a tapping sound from the front of the engine at the moment, and the idle seems slightly poor when the lights are switched off. Could this be the valve clearances that need adjusting or the timing chain that needs replacing?

Thanks.

 

[r-reg-sr]

Clean idler valve mechan ism ?

 

[SteveJones]

That wouldn't be the cause of the tapping though would it?

 

[r-reg-sr]

True