How does a 2004 a Montero Limited Rear Cam Sensor Plate crack? Mechanic told me it was cracked after he fixed both valve cover gaskets. ???

 

The only time cam sensor plate can crack is when it is installed incorrectly. Several common errors occur during install:
1. the sensor is not fully aligned with the notches on the camshaft,
2. o-ring is not properly lubricated,
3. the whole thing is slightly cockeyed...
If any of these occur and you try to "fix" it by tightening the mounting bolts on the rear plate of the camshaft sensor - it will crack that back plate. The proper way to fix it is to take the sensor out completely, lube the o-ring, carefully align everything, install sensor plate by hand with slight back and forth rotation. Once it is fully seated - torque the two bolts in the back.