We had our truck parked our truck on a Sunday evening, did not start the truck till Tuesday morning, as soon as we started it, it had a loud tapping sound and we had no indications before that anything was wrong. The check engine light did not come on, we checked the oil it was fine. We actually had the oil changed and still the sound is there. What could it be? Any help is appreciated.
If the noise is coming from the top of the engine, you may have a collapsed lifter or loose rocker arm. Identify which side the noise is coming from, remove that valve cover and check for loose rocker arms.