Strange Noise In Idle

[GnashVillain]

I am new to the Ranger Station and thought I would try it out. I recently bought a used ranger with 74000 miles and am noticing a noise coming from behind the passenger side headlight when in idle. i replaced the dirty air filter thinking it was clogged and resonating. it didn't help. it sounds like a constant tone around 800 hertz. it seems to go away when i accelerate, but i don't know if its just getting muffled by the engine revving up. i don't know how concerned i should be about this. sounds a little strange though.if anyone has any insight, i would really appreciate it.

 

[KELLY88]

Can you describe the noise in any detail? Does it sound like a vacuum leak, some kind of hissing sound, a metal on metal sound or something else. Also can you pinpoint it any more specific than that?

Welcome to TRS by the way!

 

[GnashVillain]

it sounds like its coming from the air filter or just under it. it sounds like a fan or blower motor. not metal on metal or clicking, but a constant tone. like the vacuum is clogged or constricted or trying very hard or something. thats why i changed out the filter. it sounds like its coming right from the filter or just under it.

 

[KELLY88]

You might have a small crack in the air filter housing. Is the engine performance hampered in any way?

 

[GnashVillain]

i just looked around at the housing and didn't see anything. the noise wasn't there either. it usually sounds off when i have a bed full of furniture or am moving something. the first time i heard it i had moved a water heater for a friend. sitting in idle it was pretty loud. i'll keep an eye on it.

 

[sdietrich]

IAC (Idle Air Control)

I had the same problem. I cleaned the idle air control valve with WD-40 and that help for a little while. Then I just ended up have to replace it. But my truck sounded like a viking blowing a horn and coming in for a kill. I would get the noise sitting at a stop light but as I accelerated the noise would disappear. Hope this helps!

 

[GnashVillain]

that's really helpful. i'm going to check it out. thanks!

 

[SoLongStang9499]

yes, it sounds to be your IAC, as i had the same problem myself. Your IAC is located right behind your throttle body, it has a wire connector in it, and is bolted on your intake manifold with two 5/16 screws. unplug it and spray it with a quality carb cleaner, once dry add a drop of oil to the shaft on the inside, you'll see what i mean, hope this helps.

 

[GnashVillain]

I took the IAC off and hosed it out with some contact renu and electro wash. a bunch of black crud fell out and i re-attached it after it dried. i took it around the block and sat in park for a minute while it whistled/hummed louder than usual. after a few hours, i drove it again and it was silent. same thing this morning. it seems cured. if it starts getting loud again, i'll probably drop the forty five bucks and replace the part. thanks a lot for everyone's help.