When i start my 1997 expedition i get a loud humming noise what is this

Humming Noise Front End- Any Ideas? - Ford Explorer and Ranger ...

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Dec 18, 2008 - 19 posts - ‎16 authors
Have a 98- Eddie 4.0 SOHC, 4WD with a 100,000 mi. When driving it has a humming noise, it almost sounds like a bad tire, or a ... I start to hear the humming noise at 20 mph, it is very loud at 40 to 50 mph ... 94 XLT-95 FX4. humming gets louder as speed increases
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your differential has no effect on your rpm range the diff is part of the drivetrain components im not quite sure but this might sound like a bearing starting to go out. Question is is the noise coming from the motor or the differential to figure this out drive the vehical and while it is humming shift it in to neutral if the humming noise is still present then it would be part of the drivetrain. if the noise goes away then you know its the motor making the noise.

humming could be the motor turning round but not engaging with the flywheel. you can check this by hitting the starter with a spanner a few times. if it starts up after you have a sticking solenoid. had to do this a few times my self to get engine started. replace starter as soon as possible if it works. usually happens if you not driven car for awhile.. or you do a lot of starting and small trips.

both bearing and axles.

power steering pump make humming noise and alternator with bad shaft bearing make noise.

I have had similar complaints that turned out to be the Idle Air Control (IAC) solenoid. The solenoid can get a little weak and air coming in through the intake at certain speeds can cause it to start vibrating. It sets off a moaning sound that resonates through the intake ducts and can get VERY loud. Sometimes it almost sounds like a fog horn.

If this is the type of noise you are hearing, replacing the IAC will fix it.

Other than that, the only suggestion I have is to see if you can get it to make the noise while the vehicle is sitting still. Slowly accelerate the engine speed with the vehicle stopped and the transmission PARK to see if it will make the noise. If the vehicle has to be moving to make the noise, then that eliminates several possibilities like the IAC, fan clutch, pullies, etc.....things that operate the same whether the vehicle is moving or sitting still.

Is it running rough as well? If so sounds like the timing chain may have jumped.

Need to check for any loose belts first .

Replace "idle speed motor" (also known as idle air contrl valve).

If it was your cranshaft making that kind of noise.your motor would have frozen up already.it seems more like a tranny problem than an engine problem. Take it to a good mechanic. It sounds like your tranny is about to go.