'99 4x4 - Bearing Noise?

wa2be · Jan 7, 2008

About a year ago a loud whistling/high pitched noise started up in my front end, coming from both sides. I took it in to the mechanic and they told me my wheel bearings were bad. I had them put on new hub/bearing assemblies and the noise went away, until this winter. Now it's back again, and I'm wondering if it ever was the wheel bearings to start with. These new bearings are only a year old, and I barely drive the truck as it's not my daily commuter. Basically just use it when the snow gets deep or I need to haul something.

Any ideas on what could be causing this noise? It literally sounds like somebody whistling, and the pitch of the noise gets lower as I slow down. Hitting the brakes seems to have no effect on it (and my brakes pads are in good shape). I don't hear the noise above about 20 mph, but it could just be getting drowned out by the sound of the engine. I replaced the vacuum hubs this winter with the AVM manual hubs, but it was making this sound before the hub replacement.

Silverado · Jan 7, 2008

When you switched out to the AVM hubs, did you plug the vacuum lines that used to lock your hubs? A whistling noise sounds like vacuum to me...

bgdaddy000 · Jan 7, 2008

Jack the truck up and grab the top and bottom of the wheel and check for slack. If there is no slack and the wheel spins smoothly chances are your bearings aren't bad.

4x4RangerGuy · Jan 7, 2008

I doubt its the wheel bearings since they were replaced so recently.

Check your engine compartment. What you're describing could be a pulley making noise, but you'll have to track it down.

In these scenarios, it's incredibly handy to have a mechanic's stethoscope to listen to everything spinning. Bad bearing noise is very evident.

wa2be · Jan 8, 2008

Silverado said:
When you switched out to the AVM hubs, did you plug the vacuum lines that used to lock your hubs? A whistling noise sounds like vacuum to me...

I was thinking it could be those vacuum lines, although it's been making this noise long before I put the AVM hubs on. I'm planning on looking at it tonight after work. I was gonna check for play in the wheels, but I will also plug those lines to see what happens.

wa2be · Jan 8, 2008

So I checked the wheels for play, there is none. They feel nice and tight. I disconnected and plugged the vacuum lines that I no longer need because of the AVM hubs. Took it for a drive around the block, and the noise is still there, still sounds the same. I had the hubs locked in. I discovered that if I unlock them, the noise goes away. I then re-locked the hubs, and it came back. Also figured out that it's coming from the passenger side only. So my question is this: given that the noise only occurs when the hubs are locked in, what could be causing this?

4x4RangerGuy · Jan 9, 2008

Have you checked your front differential fluid? How do the CV axles look?

polaris341 · Jan 10, 2008

hey give your front drive shaft a shake. you might have the same problem as i have. the bearing in the back of my front drive shaft is gone and it makes a rattling pinging sound when 4x4 is disengaged

wa2be · Jan 16, 2008

polaris341 said:
hey give your front drive shaft a shake. you might have the same problem as i have. the bearing in the back of my front drive shaft is gone and it makes a rattling pinging sound when 4x4 is disengaged

I checked the drive shaft, it's nice and tight with no play at all. I'm running out of ideas on this. I'm a pretty amateur 4x4 guy and don't know a lot about how the whole system works. Any other suggestions out there?

Barney0024 · Jan 17, 2008

That noise is coming from the wheel seal. On Rangers and B4000's with pulse vaccum lock hubs there is a seal located inside of the steering knuckle behind the hub. It is also known as a vaccum daiphram. This seal mates to the axle shaft on the backside of the steering knuckle. The design leaves it partialy exposed to dirt, water, salt etc. these seals are lubricated with wheel bearing grease. If not lubricated, as they wear they start to whistle when the axleshaft turns. Eventually the seal fails and the 4x4 ceases to operate.

Remove the hub/wheel bearing assembly and the shroud on the back of the steering knuckle. push lightly on the axle shaft until you can see the sealing surface. If the seal looks bad replace it. Check the mating surface on the axleshaft for scoring. the seal in the steering knuckle is spring loaded and if it is exposed it can score the surface on the axleshaft.

Some people will tell you that this seal doesnt matter if you have changed to manual locking hubs. This is not true. Even though the hub/wheel bearing assembly is a sealed unit there is one roller bearing pressed in the hub that the axleshaft rotates in. If that goes you can damage the axleshaft and that repair isnt fun to do.

My 4x4 stopped working on my 98. I ended up replacing the hub and seal after all kinds of other parts were replaced. the cause of all the problems was that stupid seal. A $50 part at ford cost me hundreds of dollars.

Hope this helps

wa2be · Jan 17, 2008

Barney0024 said:
That noise is coming from the wheel seal. On Rangers and B4000's with pulse vaccum lock hubs there is a seal located inside of the steering knuckle behind the hub. It is also known as a vaccum daiphram. This seal mates to the axle shaft on the backside of the steering knuckle. The design leaves it partialy exposed to dirt, water, salt etc. these seals are lubricated with wheel bearing grease. If not lubricated, as they wear they start to whistle when the axleshaft turns. Eventually the seal fails and the 4x4 ceases to operate.

Remove the hub/wheel bearing assembly and the shroud on the back of the steering knuckle. push lightly on the axle shaft until you can see the sealing surface. If the seal looks bad replace it. Check the mating surface on the axleshaft for scoring. the seal in the steering knuckle is spring loaded and if it is exposed it can score the surface on the axleshaft.

Some people will tell you that this seal doesnt matter if you have changed to manual locking hubs. This is not true. Even though the hub/wheel bearing assembly is a sealed unit there is one roller bearing pressed in the hub that the axleshaft rotates in. If that goes you can damage the axleshaft and that repair isnt fun to do.

My 4x4 stopped working on my 98. I ended up replacing the hub and seal after all kinds of other parts were replaced. the cause of all the problems was that stupid seal. A $50 part at ford cost me hundreds of dollars.

Hope this helps

Thanks for the input. I will check it out this weekend and see what I can find.

Barney0024 · Jan 17, 2008

if you remove the hub and replace the wheel seal, make sure you replace the 2 o-rings as well

wa2be · Jan 24, 2008

Barney0024 said:
if you remove the hub and replace the wheel seal, make sure you replace the 2 o-rings as well

What all is involved with pulling off the hub assembly? I looked in my Haynes repair manual and it makes mention of several "special" tools that are required for this job. I don't know if it makes sense to spend a lot of money on tools that I will probably only use once, as compared to taking it to a mechanic to have them replace the seal.

4x4RangerGuy · Jan 24, 2008

wa2be said:
What all is involved with pulling off the hub assembly? I looked in my Haynes repair manual and it makes mention of several "special" tools that are required for this job. I don't know if it makes sense to spend a lot of money on tools that I will probably only use once, as compared to taking it to a mechanic to have them replace the seal.

There is an excellent write up on replacing the hub assembly in the Tech Section. Check it out.

Jefers · Jan 30, 2008

Barney0024 said:
That noise is coming from the wheel seal. On Rangers and B4000's with pulse vaccum lock hubs there is a seal located inside of the steering knuckle behind the hub. It is also known as a vaccum daiphram. This seal mates to the axle shaft on the backside of the steering knuckle. The design leaves it partialy exposed to dirt, water, salt etc. these seals are lubricated with wheel bearing grease. If not lubricated, as they wear they start to whistle when the axleshaft turns. Eventually the seal fails and the 4x4 ceases to operate.

Remove the hub/wheel bearing assembly and the shroud on the back of the steering knuckle. push lightly on the axle shaft until you can see the sealing surface. If the seal looks bad replace it. Check the mating surface on the axleshaft for scoring. the seal in the steering knuckle is spring loaded and if it is exposed it can score the surface on the axleshaft.

Some people will tell you that this seal doesnt matter if you have changed to manual locking hubs. This is not true. Even though the hub/wheel bearing assembly is a sealed unit there is one roller bearing pressed in the hub that the axleshaft rotates in. If that goes you can damage the axleshaft and that repair isnt fun to do.

My 4x4 stopped working on my 98. I ended up replacing the hub and seal after all kinds of other parts were replaced. the cause of all the problems was that stupid seal. A $50 part at ford cost me hundreds of dollars.

Hope this helps

Barney0024, I have a 1994 Ranger 4X4 with manual hubs and I am experiencing the same 'whistling' problem when I drive in 4X4. Do you know if trucks w/out the vacuum locking hubs have the wheel seal?

wa2be, any luck changing your wheel seals?

'99 4x4 - Bearing Noise?

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