Whiny engine + rear-end

[Majisto]

Hey guys. 2000 Explorer XLT 4.0 SOHC V-6 with 72K miles. I've done routine oil, tranny changes on it, but recently for the past 5K miles or so, the engine has started to whine a little around the 2,500 RPM range or so while accelerating. It's a very hard sound to describe, but it's a very noticeable sound because it is NOT a normal engine sound. I am thinking maybe a lifter is going out, but I hope not...

Also, my friend once told me when he was riding in the back that he heard this strange whining sound coming from the rear-end. I can't hear it up front, but I had my dad drive the car and me sit in the back, and I heard it also. What could be causing this? Thanks guys. I love the truck, but it's hitting 73K miles, and it's time to take better care of it.

 

[Alec]

I think the SOHC wining can come from a loose intake manifold.

 

[Majisto]

Originally posted by Alec
I think the SOHC wining can come from a loose intake manifold.

Hmm i'll look into that. I need to replace the air filter, but i've never messed with the manifold. What would I do to correct the problem? Just tighten a bolt or two?