Leaking oil on rear driver's side wheel. Hub seal? How hard to replace?

you will have to dimantle rear hub withdraw driveshaft and replace seal oon axle drain axle oil first square drain plug in centre of axle hope this helps

If it's oil, your axle seal is leaking, and will need to be replaced. That will involve taking the rear diff apart. If it is brake fluid, you just have a leaky wheel cyllinder. Determine for sure which it is before you start spending money.

It shouldn't have grease are you sure it's not gear oil? And if it is leaking gear oil that means the seal at the axle hub is bad and needs to be replaced. Sounds bad but not to hard to replace, The seal is only a couple of dollars if you do it yourself! Make sure that it is not your brake caliper or wheel cylinder leaking.

what about it?

conventional axle or limited slip? Get axle code off door sticker.

SECTION 205-02: Rear Drive Axle/Differential - Ford 8.8-Inch Ring Gear 1998 Explorer/Mountaineer Workshop Manual
IN-VEHICLE REPAIR Rear Wheel Bearing and Axle Shaft Oil Seal -4.0L SOHC and 4.0L EI, Conventional
Special Tool(s) Axle Seal Replacer
T83T-1175-A Axle Wheel Bearing Puller
T83T-1225-A Axle Wheel Bearing Replacer
T83T-1225-B Driver Handle
T80T-4000-W Impact Slide Hammer
T50T-100-A
Removal

1. Remove the axle shaft; refer to Axle Shaft in this section.

Axle Shaft Removal

1. CAUTION: Do not use heat to loosen a seized lug nut. Heat can damage the wheel (1007) and the rear wheel bearings (1225).
   Loosen the lug nuts (1012).
   1. Remove the center cap.
   1. With the weight of the vehicle on the wheels, loosen the lug nuts.

1. Raise and support the vehicle.

1. Remove the wheel and tire assembly.
   1. Remove the lug nuts.
   1. Remove the wheel and tire assembly.

1. Remove the axle housing cover (4033).
   1. Loosen the axle housing cover bolts (4346) and drain the rear axle (4001).
   1. Remove the axle housing cover bolts.
   1. Remove the axle housing cover.

1. Remove the rear disc brake rotors (2C026); refer to Section 206-04 .

1. CAUTION: Once the differential pinion shaft (4211) has been removed, turning the differential case (4204) or an axle shaft (4234) will cause the differential pinion gears (4215) to fall out of the assembly. This could result in chipped or damaged components.
   Remove the differential pinion shaft.
   1. Remove the differential pinion shaft lock bolt.
   1. Remove the differential pinion shaft.

1. CAUTION: Do not damage the rubber O-rings in the U-washer grooves.
   Remove the U-washers (4N237).
   1. Push the axle shafts inboard.
   1. Remove the U-washers.

1. Reinstall the differential pinion shaft.
   1. Install the differential pinion shaft.
   1. Install the differential pinion shaft lock bolt finger-tight.

1. CAUTION: Do not damage the inner wheel bearing oil seal (1177).
   Remove the two axle shafts.

Installation

1. Lubricate the lip of the inner wheel bearing oil seal.
   • Use Premium Long-Life Grease XG-1-C or equivalent meeting Ford specification ESA-M1C75-B.

1. CAUTION: Once the differential pinion shaft has been removed, turning the differential case or an axle shaft will cause the differential pinion gears to fall out of the assembly. This could result in chipped or damaged components.
   Remove the differential pinion shaft.
   1. Remove the differential pinion shaft lock bolt.
   1. Remove the differential pinion shaft.

1. CAUTION: Do not damage the inner wheel bearing oil seal.
   Install the two axle shafts.

1. CAUTION: Do not damage the rubber O-rings in the U-washer grooves.
   Install the U-washers.
   1. Position the two U-washers on the button end of the axle shafts.
   1. Pull the axle shafts outward.

1. Install the differential pinion shaft.
   1. Align the hole in the differential pinion shaft with the differential pinion shaft lock bolt hole.
   1. Install the differential pinion shaft lock bolt.

1. Install the rear disc brake rotors; refer to Section 206-04 .

1. Install the axle housing cover and fill the rear axle housing (4010) with 2.4 liters (5.5 pints) of specified lubricant; refer to Axle Housing Cover in this section.

1. WARNING: Always remove any corrosion, dirt or foreign material that may be present on the mounting surfaces of the wheel or the surface of the wheel hub or rear disc brake rotor that contacts the wheel. Installing wheels without proper metal-to-metal contact at the wheel mounting surfaces can cause the lug nut to loosen and the wheel to come off while the vehicle is in motion, causing loss of control.
   Clean the wheel hub and mounting surfaces.

1. Install the tire and wheel assembly.
   1. Position the tire and wheel assembly.
   1. Install the lug nuts and lower the vehicle.
   1. Tighten the lug nuts.
   1. Install the center cap.

1. CAUTION: Never remove the axle shaft oil seal by itself. Always remove the rear wheel bearing and the axle shaft oil seal at the same time.
   NOTE: If the axle shaft oil seal is leaking, the axle housing vent may be plugged with debris.
   Use Impact Slide Hammer and Axle Wheel Bearing Puller to remove the rear wheel bearing and the axle shaft oil seal.

Installation

1. Lubricate the new rear wheel bearing.
   1. Use Thermally Stable Rear Axle Lubricant XY-80W90-QL or equivalent meeting Ford specification WSP-M2C197-A.

1. Use Axle Wheel Bearing Replacer with Driver Handle to install the rear wheel bearing.

1. Lubricate the lip of the new axle shaft oil seal.
   • Use Premium Long-Life Grease XG-1-C or equivalent meeting Ford specification ESA-M1C75-B.

1. Use Axle Seal Replacer with Driver Handle to install the axle shaft oil seal.

1. Install the axle shaft; refer to Axle Shaft in this section.

REMOVAL & INSTALLATION Except Miata FRONT

1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
2. Remove or disconnect the following:
   • Steering knuckle from the vehicle
   • Inner oil seal from the knuckle
3. Using Mazda Hub Puller tools 49 G033 102, 49 G033 104 and 49 G033 105, pull the front wheel hub from the knuckle assembly.
4. Remove or disconnect the following:
   • Bearing inner race from the front wheel hub
   • Retaining ring from within the knuckle
   • Front wheel bearing from the knuckle, using the hub puller tools
   • Brake dust shield
5. Clean and inspect all parts but do not wash or clean the wheel bearing. The bearing must be replaced. To install:
   
6. Using Mazda Press tools 49 G033 107 and 49 H026 103, install a new dust shield cover assembly to the knuckle.
7. Using the press tools, press a new wheel bearing into the knuckle assembly.
8. Install or connect the following:
   • Wheel bearing retaining ring
   • New oil seal using Installation tool 49 V001 795
   • Front wheel hub using the Mazda press tools

REAR

1. Before servicing the vehicle, refer to the precautions in the beginning of this section. NOTE: The wheel bearings are not serviceable. If the bearings are bad, a new hub/bearing assembly must be installed.
   
2. Remove or disconnect the following:
   • Rear wheels Fig. 1: Exploded view of the rear wheel hub and bearing assembly (disc brake model shown, drum is similar)
     
     
   • Brake drum, if equipped
   • Rear caliper and rotor assembly from the hub, if equipped
   • Hub dust cover
3. Raise the staked portion of the hub retaining nut with a hammer and chisel.
4. Remove or disconnect the following:
   • Hub retaining nut and discard it
   • Hub and bearing assembly from the spindle Fig. 2: When installing the new hub nut, be sure to stake it into the notch on the spindle
     
   To install:
   
5. Install or connect the following:
   • Bearing assembly on the spindle. Torque the new nut to 131-173 ft. lbs. (177-235 Nm)
   • Stake the nut into the groove in the spindle
   • Dust cover
   • Assemble the brakes
   • Rear wheel

And you want to know what?

Remove the axle and replace the seal,not all that hard.

The adjuster is just like on a car with drum brakes. It can be adjusted with the wheels still on the truck, but if yours is out enough that it doesn't work, an inspection is warranted. Axle seal failure is common and will soak the shoes.

Jacked both rear wheels off ground, and while slowly spinning wheel, tighten the star-wheel adjuster until you just hear and feel brake drums rubbing, then loosened slightly.
There's a plastic dust cover about 1/4" X 1" that you remove, and use a drum brake adjuster tool.

The driverside access hole is below axle, easily accessable. To tighten driver side rear parking brake, turn star-wheel adjuster down.


The passengerside access hole is found above axle, and difficult to see. Removed pass side wheel and used an inspection mirror.
To tighten passenger side rear parking brake, turn star-wheel adjuster up.

Good luck and hope this helps. Oh and the other thing to is that if you do smell axle fluid around the wheels and see oil leaking from the drum area. Then you have a axle wheel seal and or bearing gone bad too.

it is best to replace both sides when doing these because usually when one goes out the other side goes next to replace remove the wheel then remove brake caliper hang it out of way pry dust cover off of hub using a screw drive hammer or chisel straighten out bent cotter pin remove the lock nut and washer pull the hub and assembly out slightly and then use a screw driver to remove the seal out of the rear of the hub and remove the inner wheel bearing from the hub use a high temp bearing grease to repack the bearings and work the grease completely in the rollers

If no oil on the driver side, you have a locked up parking brake pivot. Follow the park brake cable to the inside plate of the rear wheels. on the outside, where the cable connects, look to see the position of the visible mechanism connected to the cable. It probably will not match the side that is not locked up. This is a very common problem; you need to replace the park brake pivot. Additionally, you are going to need to remove the other side axle shaft and get the leaking oil seal replaced. Replace the brake shoes if they have oil on them.

1. for drum brakes with sealed hub(all one piece) remove lug nuts and wheel.
2. spray penetrating oil around studs if there is a big phillips head screw visible remove it with impact driver/if not use big ballpeen hammer ,tap on flat of drum near studs(becareful not to hit them) until drum loosens(your creating a shockwave to loosen rust)
3. once drum is off there are 4-bolts coming in from behind backing plate, remove them then hub should be able to be removed w/a little persuation from hammer.

with out sealed hub ,

1. remove wheel
2. remove dust cap,cotterpin,star washer(if equipped) do not re use cotter pin
3. remove nut then washer, wiggle brake drum and front bearing will come out.
4. put nut on shaft tighten 2-3 turns grab drum by sides and pull towards you this should remove drum leaving inner bearing/seal on shaft
5. to replace reverse procedure making sure to pack new bearings w/grease(take drum and use long punch to remove bearing races, use race/seal installer to install new races

with disk brakes

1. remove wheel
2. remove caliper/bracket
3. remove rotor
4. remove 4-bolts from behind,tap old hub out
5. reverse procedure