Goomba2469

My girl would like to know how this happened to the 2002 Explorer XLT 4.0 SOHC she luvs to drive so much. It was running fine hit a big bump, or pothole entering a parking lot. After her visit there she started the Explorer and it was running ruff. Proceeded to turn off and got out to notice oil on the pavement. Popped the hood, and with her trusty " girl phone " put on magnifier with light. All by herself she found the rear right side valve cover had somehow experienced catastrophic failure, and produced a large hole where the gear, and chain appear through such a hole. She would like to know how this happened. She found multiple pictures simular to her valve cover image, but no ansewer. Take all the feedback explorerforum.com can offer. Thanks Goomba2469