Odd rattle. Chain guides or something else?

[Bsmalone]

2004 Ford ranger 4.0 5 speed 4x4. 178k miles. All stock components.

Just picked up this truck, has a odd condition rattle noise. It only rattles when revving down from above 2600, doesn't rattle on cold start. Doesn't rattle on idol. Rev less than 2600 and it won't rattle but when revved up above that and left off it'll rattle for about 1 second and go back to normal. I know quite a bit about the guide wear on these engines that was "fixed" in 03. And typically that would rattle at cold start and idol which makes me think it could be something else. I've attached a link to a video that shows the rattle. Any ideas or suggestions before I rip it apart would be appreciated. Thanks

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[DILLARD000]

Hard to tell from your video\audio. Assume Left+Right OilPressurized TimingTensioners have never been replaced?
Should be a factory date stamp on the outer ends of the Tensioners; if they're 2004\Earlier, they need changing.
I'd start with those & a fresh Oil+Filter change.
Stethoscope on front end of LeftValveCover, rear end of RightValveCover, listen to those TimingChains.
To fully confirm condition of Left+Right TimingCassettes, need to:
~ drop OilPan & check for broken plastic pieces from TimingGuides.
~ open Left+RightValveCovers & inspect TimingCassettes directly.
Click here for more info on the OilPressurized TimingTensioners.

 

[Uncle Gump]

It sure sounds "metalic".

With their known issues... and probably unknown maintenance record... I agree with @DILLARD000. An exception of the first thing to do is drop the oil pan. If you have trash on the bottom you will feel better not throwing 5 qts of oil and a filter away. If there is nothing in it... it will be like winning the lottery and you can be more confident when you replace the tensioners and do an oil change.

 

[DILLARD000]

"Winning The Lottery" that's a good analogy!

 

[RonD]

When engine is stone COLD...............remove fan belt from crank pulley
Start engine and listen
You can only run the engine without a water pump for under 2 min
But you can repeat this anytime engine is cold again

Engine bay will be VERY QUIET with no fan or accessories moving, so much easier to localize a noise

If no noise then shut off engine and spin accessory pulleys by hand, one of them could be the noise