2004 Ford F150 V8 Four Wheel Drive Automatic 67000 miles
I have a 2004 F150 FX4. While driving it down the road at about 40mph I heard a loud growling noise from under the hood. Not know what it might be I pulled off the road immediately into a parking lot and stopped leaving the engine running. The noise stopped before I could open the hood to see where it was coming from. After looking under the hood and finding nothing I decided to turn off the motor an then restart it. Discovered now the battery was dead. Also, before shutting off the engine, I noticed the ABS warning light was illuminated. With the help of a jumpstart I was able to get the truck running and drove it to the dealership about 2 miles away. They looked at it and replaced the battery. Everything was fine for two days afterwards. Then will driving it on day three the noise came back and the dashboard charge indicator showed no-charge. I immediately drove my car home it made the growling noise all the way home pulled into my driveway stopped and turned off the motor and then attempted a restart, battery wouldn't even turn over the engine. Put a battery charger on and charged the battery its starts and the charge indicator on the dash show the alternator is charging. Bought a code reader and it shows no error codes on the system and it verifies that that alternator is taking a load. No noise coming from the alternator. My theory of what is wrong is the alternator is bad and drops offline and causes the AC compressor clutch chatter causing this noise. The alternator nor any pulley's seem to have bearing issues and the belt seems tight. Any contrary thoughts would be appreciated or helpful hints on what I should look for?
Crank pully is equipped with harmonic damper and if the damper has failed, it would result in the outer pulley ring slipping on its axis and when this occurs, it would result in abnormal noises and the alternator would not be providing sufficient charge as it is turning at a speed lower than required. The A/C might not feel as cold and steering effort could be harder.
When engine is running, check the crank pully for wavy movements.