Leaking rear differential seals on 4WD models

You will need to remove the rear diff cover. There is a small bolt that secures the pin that the spider gears ride on. remove this bolt, and then remove the pin(you might call it a shaft). Remove the caliper and rotor from the side you are replacing, and push the axle in. Inside the differential, you will see what we call a c-clip on the end of the axle shaft you just pushed in. Sometimes this clip if it is in the right position, will fall out on it's own. If not, slide it off, and go pull the axle out. Now you can pry out the seal and replace it. There will be a pipe plug with a square recess on the front side of the differential. You can put a 3/8 drive ratchet in the recess and unscrew it. This is the fill plug. You fill the rear end untill it runs back out of this hole. It will be located about half-way up from the bottom of the differential housing.

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.

Hello Barry.
There is a flange attached to the pinion shaft that drives the gears inside the differential.
This flange is held to the shaft by a large nut threaded onto the pinion shaft.
On the flange there is a machined surface the seal rides on to retain oil inside the differential.
Sometimes rust can develop on this surface and tear the seal. Also debris could damage it as well.
Or in a worst case scenario the bearing that the pinion shaft turns on goes bad and allows the flange to wobble.
It will take an experienced mechanic a little over an hour to replace the seal.
The large nut on the pinion flange needs to be properly torqued and takes a proper torque wrench to do it.

Thank you for using FixYa.

KL

Axle Vent
NOTE: If the vent cannot be cleared, it must be installed new.
A plugged vent will cause excessive seal lip wear due to internal pressure buildup. If a leak occurs, check the vent. Make sure the vent hose is not kinked. Remove the hose from the vent nipple and clear the hose of any foreign material. While the hose is removed, pass a length of mechanics wire or a small diameter Allen wrench in and out of the vent to clean it. Connect the hose when done. The vent is located on the drivers side top of axle housing.
If you plan on doing most repairs yourself I would suggest buying a Haynes or Chilton manual for your particular vehicle. Or there are some data disks on e.bay($12-$15) For a cost of under $25, you can almost do any repair yourself with these manuals.Also there are online manuals like the site called ALLDATA where guides can be viewed for a fee. All these solutions will save you time and money, and give peace of mind over correct repairs. I can post you some procedures here also.

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

7.Remove the rear disc brake rotors You will have to remove the brake caliper to get rotor off.
8. 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.
9.
1.Remove the differential pinion shaft lock bolt. 2.Remove the differential pinion shaft. 10.CAUTION: Do not damage the rubber O-rings in the U-washer grooves. Remove the U-washers (4N237).

1. Push the axle shafts inboard.
2. Remove the U-washers.

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

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

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.

Axle bearing puller end..
Installation
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.
2. Remove the differential pinion shaft.
3. Remove the differential pinion shaft lock bolt.
4. Remove the differential pinion shaft.

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

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.

Install the rear disc brake rotors; Install the axle housing cover and fill the rear axle housing (4010) with 2.4 liters (5.5 pints) of specified lubricant
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. Install the tire and wheel assembly.
Position the tire and wheel assembly. Install the lug nuts and lower the vehicle. Tighten the lug nuts. Install the center cap. WHEW Hope this can help you

Axle Shaft Removal

1. Raise and support the vehicle. For additional information, refer to Section 100-02 .

1. Remove the wheel and tire assembly. For additional information, refer to Section 204-04 .

1. Remove the differential housing cover (4033).
   1. Loosen the bolts and drain the lubricant from the rear axle housing (4010).
   1. Remove the bolts.
   1. Remove the differential housing cover.

Remove the rear brake disc (2C026). For additional information, refer to Section 206-04 .

1. CAUTION: Turning the differential case (4204) or an axle shaft (4234) with the differential pinion shaft (4211) removed will cause the differential pinion gears (4215) to fall out of the assembly and damage the components.
   Remove the differential pinion shaft.
   1. Remove the differential pinion shaft lock bolt.
   1. Remove the differential pinion shaft.
2. CAUTION: Do not damage the rubber O-ring in the U-washer groove.
3. Remove the U-washer (4N237).
4. Push the axle shaft inboard.
5. Remove the U-washer.

Reinstall the differential pinion shaft.

1. Install the differential pinion shaft.
2. Install the differential pinion shaft lock bolt finger-tight.
3. CAUTION: Do not damage the wheel bearing oil seal (1177).
   Remove the axle shaft.

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Seal Removal

1. Remove the axle shaft (4334). For additional information, refer to Axle Shaft in this section.

1. CAUTION: Never remove the wheel bearing oil seal (1177) by itself. Always remove the rear wheel bearing (1225) and the inner wheel bearing oil seal at the same time.
   NOTE: If the wheel bearing oil seal is leaking, the axle housing vent may be plugged with foreign material.
   Using the special tools, remove the rear wheel bearing and wheel bearing oil seal together.

Installation

1. Lubricate the new rear wheel bearing.
   • For 4.0L SOHC and 4.0L EI with limited slip rear axles and 5.0L vehicles, use SAE 75W-140 High Performance Rear Axle Lubricant F1TZ-19580-B or equivalent meeting Ford specification WSL-M2C192-A.
   • For 4.0L SOHC and 4.0L EI with conventional rear axles, use SAE 80W-90 Premium Rear Axle Lubricant XY-80W90-QL or equivalent meeting Ford specification WSP-M2C197-A.

1. Using the special tools, install the rear wheel bearing.

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

1. Using the special tools, install the wheel bearing oil seal.

1. Install the axle shaft. For additional information, refer to Axle Shaft in this section.