I was looking at a relatives 1997 F-150 the other day since he claimed it was making a "clunk" or "popping" type noise from under the hood shortly after being started. Anyways, I found that the sound was coming from a black plastic box located directly behind the passenger side headlight almost mounted up in the fender(I can take pictures if none of you know which box I'm referring to). Any of you guys happen to know what this box contains or what it's for? Everything is working on the truck as far as I know and it did not make this noise until now(my brother-in-law has owned it for over five years now for what it's worth). I searched the forum here and found a similar post, but everyone seemed to chalk it up to being the ac compressor on their trucks. Thanks in advance for any info.


EDIT: I just wanted to clarify that the part I'm describing is not the black plastic item located directly behind the battery, the one I mentioned is located farther forward towards the headlight.

 

thats the washer fluid resivoir thats right behind the passenger headlight