Got a 5.9 about 4 years ago. Started hearing crickets noises on drivers side under hood. Noises only start after truck is warm ( driving for 5 mins. or so ) Only after 35 mph. Crickets are constant noise, will not vary with speed, Sounds like metal to metal chatter. Will stop chattering after dropping below 25 mph. Will not chatter at idle. Driving me nuts!!!!