Sounds like marbles in the engine?

Hi, I have a 99 isuzu trooper with 160k miles and it started like it had Marbles in the engine. It happened as i was driving home. There was no loss of power, engine sounds good and strong other then the knocking and the oil is good. My dad and I am going to take it apart to see if we can find what is making the sound. We also cant really tell if it is from the top or bottom part of the engine. If you have any suggestions please let me know! :runaround:

get a stethoscope and listen to the top and bottom end while it is running. check every 4 inches or so. you will pinpoint it real quick.