well my 98 sunfire waterpump was forced to run dry due to a little black plastic piece thatsends out coolant to the waterpump had a small crack and leaked without any evidence sowhen the gear on the waterpump spun wrong it threw my timing off and it sent a piston into my valves and good bye first 2.4l so went to the mechanics and he had found me a new 2.4 got it in my car to find out that unburnt fuel is blowing back threw my intake instead of out my exsaust if anyone has experienced this PLEASE email me with the fix thanks very much