So I have never had a problem with my ranger so far since owning it, 300k miles, yea its alot, still great, i realized today when i got home from the store during idle my truck is making a high pitch noise coming from under the truck, id say right under the drivers seat, its not a loud noise but goes on and off with 5 second intervals, gave her a little rev and the noise doesnt happen while revving or driving, only in idle, anyone have any ideas on what it could be? nothings wrong just a noise and dont want to ignore it and it become a big problem. can take videos if needed.

 

Welcome to the form

You have a 2.3l Duratec 4cyl DOHC engine, just FYI

So should be looking in this sub-forum: https://www.ranger-forums.com/dohc-2...l-engines-136/

Not sure on the noise never own one of these engines, but look in that other forum for posts about noises

Noise locations can be deceiving
When engine is stone cold remove fan belt from crank pulley
Start engine
With no fan or accessories spinning engine bay will be very quiet
See if you can better locate the noise, if no noise then might be a fan belt pulley

You can ONLY run the engine with no water pump for 60-90seconds which is quite a long time but no longer
You can repeat this test as much as you like, but engine must sit for quite awhile to cool down