humming sound

[joelzkins]

I have noticed a slight humming noise coming from my passenger side under the hood area. I thought is was the alternator so i replaced it twice. new cables, new battery. it just charges weakly. never above half.... the head lights alone take down a good bit. i was told to look for shorts. i have been. pulled the fuses to c and no difference. any ideas? its like a electrical hum. it does it most of the time now. 89 b2

 

[Explorin94]

Check the air box and everything related to it. Sometimes if you don't get the lid on right or the inlet tube is somewhat plugged it starts to suck air and vibrate thus making a humming noise

 

[06RangerXLT]

could be a blower motor or the motors that move the airflow from floor to window.

 

[joelzkins]

I took off the air box it has an after market filter on it. the blower motor is fairly new. I also wondered if it was vacuum leak but it just sounds like a intense little hum that was never there before. its getting worse though i think. it seems to be getting louder.

 

[Earl43P]

Disconnect the IAC. They hum.

 

[adsm08]

the motors that move the airflow from floor to window.

Doubtful since he has no such items. The whole system is cable controlled in 85.

I took off the air box it has an after market filter on it. the blower motor is fairly new. I also wondered if it was vacuum leak but it just sounds like a intense little hum that was never there before. its getting worse though i think. it seems to be getting louder.

Vacuum leak is unlikely, since it should go away as soon as the engine is shut off. Shouldn't be a hum either.

Disconnect the IAC. They hum.

What IAC? 85 would have a 2.8. Carbs don't need an IAC.


If you aren't charging and you have changed all the parts except your voltage regulator, I bet it's the voltage regulator.


When you hear the hum just start touching things until you find one that is vibrating.

 

[joelzkins]

it has an internal regulator. whats the IAC? what is that?

 

[Explorin94]

it has an internal regulator. whats the IAC? what is that?

IAC (Idle Air Control). It is the idle circuit for a fuel injected engine.

 

[kimcrwbr1]

Unless you did a mod the 85 has a external regulator by the brake booster on the left side. Take a long screwdriver and put one end up to your ear and listen around the closer to the noise the louder it gets that might help you isolate it. For the charging check all your ground wires are good and the connections are clean and tite. Somtimes a wire looks good but has a break hidden by the insulation bend them to see if they are solid and adding a ground wire from the alternator housing to the battery - could never hurt. Make sure the battery to chassis wire is good and connections are clean.

 

[joelzkins]

Idle Air Control... oh thats right. i know where that is. i believe their only sixty bucks at oreillys.