So it started couple days ago and it doesnt happen all the time, but today it did it for about 2 hour, when i accelerate the noise quiet down or stop, when the truck stop moving, it may start again and when the A/C is on its worse, for a moment the loudest was when the engine was at aboutr 1.5k RPM, i think it may start happen when the engine is above 200F. Then ive let the truck sit for about 2 hour, started again to go home but the sound didnt came back.

This video show when it was at loudest ive heard, normally its not that loud. Note that it doesnt exactly sounds like how i heard it. But similar.

I have no idea where it comes from. Its a ranger 2000 XLT off road package.

Anyone got an idea?

Thanks

 

it's air plane noise i am having the same and i am going to replace the fan clutch soon. Moreover, i having issue of overheat.

Just try to test the fan clutch,

when its cold , it should be freely moving.
after warmup, it should be little harder.

 

I noticed the sounds wont happen when enginje is under 200F, at 210F it may happen but not loud, at 220F it may get loud.

Here a video where you could hear it more clearly. Its coming from intake.

 

This may be a bit of a stretch as I'm a 3L guy but the clutch fan on the 4L should be similar. I believe they are both driven by water pump pulley so when my fan clutch locked up it put extra strain on the water pump and killed the bearings so that may be your noise. Also 220F is a little warm for this motor i think factory t-stat is 195f on the 4.0 so you definitely want to keep the temp down 220f on the 3.0 is pushing the head gaskets pretty hard so id advise checking water pump t-stat and fresh coolant as well as a new fan clutch. With my e-fan in GA heat on a 95F day it barely flirts with 200F. Even when i ran the stock fan i never saw it climb about 205F.

 

Fan bearing or water pump bearing? When truck keep moving it stay under 200F

I also noticed that it started happening when i cleaned the MAF, IAC and throttle body.