My car has 232,000 miles on it. At 194,000 miles I did as suggested and replaced the timing chain and water pump, well my mechanic did. You can tell that the cam gear had been loose for a while, there was melted plastic everywhere the cam exploded into 9 different pieces. I inspected the cam bolt and found no evidence of "loctite". Is there any other reasons this could happen? My car has a 1.7 in it.

 

I've never heard of that kind of failure, personally. The bolt shouldn't need loctite as long as it is torqued to spec.

 

It's possible that your mechanic used the cam bolt to rotate the motor after he installed the timing belt and loosened the nut, it's happened to me. The cam wants to spin so it can be awkward to re-torque.

Unless you've had some head work done there would be no other reason to touch that bolt so it shouldn't have been loose.