I have a 2002 XJ Sport with 75k miles. Recently the engine developed a tapping noise at around 2500 RPM - no noticeable noise above or below this. It happens whether engine is warm or cold and the oil level is OK. You can hear it under acceleration at 2500 RPM or at steady speed. Otherwise engine still feels strong.

Not sure if it is serious or not. Mechanic said it could be piston rods and I may need a new engine. Replacing the engine is not an option so I need to figure whether to spend the money to diagnose further or write it off.

Anybody had anything similar or ideas on likely cause?

 

Where do you live?