1994 Oldsmobile Achieva Is my chain driven CAM gear made ou

Engine Mechanical problem
1994 Oldsmobile Achieva 6 cyl Front Wheel Drive Automatic 174 K miles

I know that I my 3.1 Liter engine has a chain driven cam gear. A mechanic told me that even though the chain driven cam isn't a belt that can break, the cam gear is not metal, that it is nylon, and the teeth will wear out, leaving me in the same situation as if I had a belt break. He says the cam gear should have been changed long before the 173,000+ miles I now have on the car. Is this true? I used to race Corvettes back in the 60s and did my own hot rodding, changing to a lot of different cams, and It is hard to fathom a nylon cam gear.?