It's been awhile since I've been on her. First off I have 04 super cab 4x4 4.0 sohc with an automatic. I have a rattle in the front of my engine. I've changed the tentioner pulley and the idler pulley. I still can't locate the source. I've been told it was the alternator and then I was told it was the timing chain. The engine has 300k on it. I was wondering if there might be a way of checking without taking it to the shop. Any advice would be greatly appreciated. Thank you.

 

Yes you can check it pretty easily
When engine is stone cold, loosen and remove fan belt from crank pulley

Start engine, battery light will stay on, no alternator
You can only run the engine for 1 minute or so without the water pump, but engine bay will be VERY QUIET with no fan
You should be able to hear if there is any engine rattle

And with fan belt off you can manually spin alternator, key off, to see if it sounds OK