I once bought an ae82 with this problem. It had broken the timing belt due to siezed cam, but had been running fine before. I removed the cam and found that some shit had got into one of the cam bearings and caused it to bind up and sieze. I managed to get it to free up but the motor was rattly as buggery afterward and only lasted a couple of days.
So from personal experience I would suggest that you don't bother just replace the motor with a wrecker special (I managed to get a fully recond one for $150 from Upullit).
