Can the timing chain tensioner cause problems after its been

[Orlando4000]

I finally found a 90 GTZ, the car made a noise while idling but if you turned the steering wheel it stoped so the guy thought it was the steering pump, I took it to a mechanic, he told me it was the timing chain tennsioner, i bought the parts, then he called me and said since it was like that for so long once it was fixed it messed up the valves, this doesnt sound right to me, so what do you guys think?

[Money pit Beretta]

So how is the idle?
If the timing was off enough then the valves can hit the pistons. Did the tensioner break?