please my people. i have 2.4 camry 2az engine and it has given me a lot of problems since i purchased it from america last year september which is only one year. the problems i am having with the care is camshaft problems. i have chaged it three times and it kept spoiling. it is making this crackling sound and it is very noisy. pls what could be the cause of this? the engine seems to be fine it is just this noise from the camshaft. i was told by a mechanic that the top cylinder is worn out that i need to get another one. but i dnt want to believe that. this car is in good condition except this camshaft. pls anyone with useful imformation should let me know pls.