Youssef_Hany1

Perhaps the chip is over heating with to much current draw?  Try connecting only two motors to see what happens.
For the l298n chip itself:
For the IO Peak Output Current (each Channel)       
– Non Repetitive (t = 100ms)            3.0A
–Repetitive (80% on –20% off; ton = 10ms)    2.5A
–DC Operation                    2.0A
TOTAL DC CURRENT UP TO 4 A