Ok, you are right, there is a hole in the bottom of the lifter, so either the cam is worn, I need to replace both, lifters and cam.There's a fair chance that the cam lobe was on it's way out at this point, which is why you heard "ticking".
Possible. Worth checking. As said...get that cylinder on TDC-Compression (NOT TDC-Exhaust) and put compressed air in the cylinder. Hissing at the throttle body is a leaking intake valve. Hissing at the tailpipe is a leaking exhaust valve. Bubbles in the radiator are a failed head gasket, or a cracked casting. Hissing at the oil-fill cap can be normal, there's always some leakage past the rings. A real, live cylinder leakdown tester used with compressed air can tell you if the ring leakage is acceptable or excessive...but all you need is compressed air to know if the valves seal.
If it didn't pull right out with your fingers...there's problems with the bottom of the lifter.
But now I'm concern about the knocking noise, if the cam lobe is totally worn out and can´t move the rocker arm, what is making that hammering, I guess the only response is the valve damaged, anyway I´ll comment to my mechanic your recomendations.
I´ll open a thread about the new cam, I have a concerns about it.
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Thanks Schurkey