Trying to figure out what is making this rattling noise and sounds like it's coming from the rear of the engine bay, i was originally leaning to it being the timing chain tensioners going out, but it rattles at the same speed all the time doesn't matter if the motor is hot or cold or if the rpm is higher. Its quiet enough to where it gets drowned out by motor noise past 1,750 rpm, but if you really listen for it it's still somewhere. Anyways just wanted to see what you all thought about it. Don't want to stress over a tensioner if it isn't it, the motor also has 190k miles mostly highway if that helps any

 

Any noise on first start, that quiets down within a second ?

#2) When cold, tap cats with a rubber mallet to see if anything is loose inside.

 

It's starts up fine, no noiseI'll check the cat when I get home, never thought of that

 

If your V6~4.0L~SOHC OilPressurized TimingTensioners are 10yrs\100kMiles+ old, they should be renewed in any case.

 

There is a 4.0 sub forum .

 

4.0L SOHC per thread title