Lately I've been getting a noticeable howling noise when driving. Usually it happens when I'm going between 40-55mph. Even if I let off the gas pedal it continues to howl. At first I thought it was my slider window, but I had that open today and that howl was loud. It doesn't seem to vary with speed. Do you think it's the fuel pump?

 

dunno if it could be the fuel pump or not, but i get a howling in mine cus the door is slightly bent.

If you want to you can test the fuel pump. you should get 1/3 pint of fuel for 10 seconds of cranking and about 7 psi IIRC

 

Oh hell, I forgot these have mechanical fuel pumps.

Sending unit? Rear axle bearings? Carrier bearing?

 

Mechanical fuel pumps do not howl, no matter how old and worn out they are. Axle gears however will howl, whine, and in extreme cases even scream shortly before they self-destruct. Jason, are you 100% certain your front locking hubs are disengaging properly? Front axle will howl sometimes if only one of the hubs is unlocked. Also, do you have a leak at the pinion seal of the rear axle? The pinion nut of these trucks sometimes loosens up, causing play in the yoke (resulting in said oil leak) but also disturbing the gear mesh inside the axle...

 

The front hubs are disengaged. I sprayed the rear end off with a pressure washer around a month ago and it's dry. I just ran out to take a look.

Thinking way back when I first bought the truck, I could've sworn I heard the same howl/whine when I first started the truck and had messed around with the front and rear tank toggle switch because I thought it was the heater fan switch.

 

If you have a long wall you can drive it along it makes it a lot easier to hear ... like the walls that are along some freeways.

-Enjoy
fh : )_~

 

Jason, are they really disengaged tho? Can you turn the half-shafts by hand?

 

I'll see if I can turn the shafts by hand in the morning before work.

 

tires?

-Matt

 

The front axle shafts turn freely by hand. The hubs are definitely disengaged.

The noise doesn't happen all of the time at those speeds. It seems pretty random. Not knowing much about these trucks, I assumed it was an electric howl and went with the fuel pump before I remembered it's mechanical.

 

A bad fan clutch can cause the howling. That's how I found my fan clutch was bad.

 

Supercab.....carrier bearing?

From the carrier bearing position on the frame, sometimes it is hard to tell where the hoise is coming from.
The frame distributes the sound so well it may sound like the front on minute and the rear the next minute.

If it is a belt squeel type of sound, vacuum pump, alternator, fan clutch, power steering pump or water pump could all be suspect.

Does it change if you hit the clutch?

Throw out bearing?

 

It's so random, I can never diagnose it. It'll come and do its really odd pulsating howl whine noise and be gone. It didn't make that noise today. The next time I hear it, I'll try the clutch.

I thought the first time I heard it, it came from towards the back. I thought it was the rear window leaking air with the heater fan on high. I shut the heater fan off and still heard the noise. I still thought it was coming from the window area.

Saturday was the first day I heard it with the rear window open. I then knew it wasn't the window and it was something more serious. It's a loud noise.

 

Update:

Now I can hear things better w/o the exhaust leaking at the firewall. I've only been able to reproduce the very loud howl a few times. It happens when decelerating and I'm almost at the stop and push in the clutch. It even happened when I let off the clutch, but quit. It seems to go away during that deceleration time when hitting bumps.

I can also hear a high pitch ringing. It starts at 40mph and is really ringing at 55mph. I can't seem to hear it when I move my head towards the supercab back seat, but definitely hear it up front. Front end bearings? Tranny? Clutch?

 

I'm thinking gear whine from inside the trans? We had a '70s Ford 4x4 and the bolt-action would whine real bad, probably was low on oil but truck got junked before I get around to inspecting it...