One problem related to engine clicking and tapping noises has been reported for the 1998 Mazda 626. The most recently reported issues are listed below.
626 taken to Mazda to have transmission checked for rough shifting and clunking noise. Mazda said the transmission was defective and needed to be replaced. Once replaced, new transmission acted in the same manner. Mazda then decided to replace all 4 motor mounts. That did not correct the problem either. The service department then told me that rough shifting and clunking sounds are normal for the 98'626. I found that explaination very hard to believe to say the least, so I am meeting with the regional sales rep for Mazda in an effort to have the problem rectified.