Z20NET tapping noise

[Kev_A]

I've noticed my Z20NET making a tapping noise recently when I've been under the bonnet, seems to be coming from the LHS (standing at the front looking down)
At first I thought it was just when the car was cold but even after running he car the noise remains.
It's due a service to be fair, I have all of the stuff there ready but I haven't done it yet due the car not being on the road (been using the work van trying to save money the past few months) the car is currently on 75k, everything else seems fine, no problems at all so I'm thinking it may be the timing chain?

[Rebellion]

Change the oil, and use a really good quality fully synthetic oil, and you may find the noise has gone.

[Kev_A]

The oil I have is GM 5w30 fully synhetic, 6L iirc

I'll change the oil and filter tommorow, I'm also doing the fuel filter too.

[john_k_sri]

If it's chain, would it not rattle?

Could it be the auxiliary belt?