Need to replace the seal at the differential

First replace the seal and case cover gasket, then top up diff oil, test to see if noisy is eliminated , because since the oil is leaking it might be running dry.

FOR oil leak issue check the following help links:---

Common Causes of Car Oil Leaks?

http://schematicsdiagram.blogspot.com/2011/12/common-causes-of-car-oil-leaks.html

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Troubleshoot Car Oil leak?

http://schematicsdiagram.blogspot.com/2011/12/troubleshoot-car-oil-leak.html
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Car oil leak?

http://schematicsdiagram.blogspot.com/2011/12/car-oil-leak.html

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Car oil leaks from valve cover gasket?

http://schematicsdiagram.blogspot.com/2011/12/car-oil-leaks-from-valve-cover-gasket.html

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Rear oil seal leaking?

http://schematicsdiagram.blogspot.com/2011/12/rear-oil-seal-leaking.html

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leaking oil from oil pan?
http://howtobyme.blogspot.com/2011/11/kia-sportage-leaking-oil-from-oil-pan.html

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leaking oil from timing cover?

http://technoanswers.blogspot.in/2012/02/toyota-corolla-leaking-oil-from-timing.html

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How to Check Differential Oil Leaks and Replace Oil
http://schematicsdiagram.blogspot.com/2011/07/how-to-check-differential-oil-leaks-and.html

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Oil leaks from air filter on ford?

http://technoanswers.blogspot.com/2012/01/oil-leaks-from-air-filter-on-ford.html

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---------This will help. Thanks.

Do you mean the seals at the hogs head? If so you purchase them drain the fuid by removing some bolts and loosing all then pry at bottom to drain. Remove old seal clean check for wear on internal parts in the differential clean off magnet if you have one. Add new seal tighten bolts replace with dealer recommend fluids and capacities

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.

Rear Axle seals are bad, they must be replaced. Good Luck

How to Fill a Rear Differential
You may need to add fluid to your differential due to leaks or changing seals, or it may be time to change out the gear oil completely. Either way, it's just a few steps to fill the rear differential and get your vehicle back out on the road!This article will explain how to fill a rear differential. jQuery('.intro .thumbnail').each(function(i,e){ jQuery(e).find('img').one('error',function(){ jQuery(e).remove(); }); }); Difficulty: Moderate
Instructions and Things You'll Need:

• 3/8 inch drive ratchet with extension
• 2 quarts gear oil (gear lube, differential fluid)
• Side cutters
• Oil drain pan
• Shop rags
• Flashlight or shop light (optional)
• Lock tight (optional)

Filling a Rear Differential

1. Be sure the car is raised on four jack stands and is level. It will be more difficult to fill the differential if you've only got it raised in the rear.
   
2. Place an oil drain pan underneath the plug to catch any leaks or drips. Keep shop rags handy for any spills.
   
3. Check your service manual for the amount of fluid your differential needs, if you're completely refilling the system. Two quarts should be enough in most cases.
   
4. Remove the spouts on the gear oil containers. Peel off seals, then replace spouts. Use side cutters (or any cutting tool you've got handy) to clip off the top of each spout.
5. Remove the differential fill plug using a 3/8 inch drive ratchet with extension. (Some models may require a hex key or screwdriver, but the 3/8 inch is the most common plug design.)
6. Take the gear oil container and fit the spout into the fill hole. Pour the fluid inside. You can gently squeeze the bottle to speed the process. Repeat with a second bottle if necessary.
7. Fill the differential until the fluid starts draining back out of the hole.
   
8. Clean and replace fill plug. Use lock tight (thread locker) to help seal if desired. You can see my eHow article "How to Replace Rear Differential Fill Plug" (video) for more information.
   
9. Take the car for a drive around the block to get the gear oil moving. When you return, check underneath for any leaks from the fill plug or differential cover.
   

Hope help with this.

You have a transmission front seal that has gone bad. The transmission will have to be removed and new seals installed.

Not that difficult, raise and support the rear of the truck and remove the wheels. Might as well replace both sides so you know you have new seals, remove the differential cover and drain the fluid. Once differential is opened and cleaned , remove the axle "C" clip that hold the axle in place and slide the axle out. Once the axle is out remove the wheel seal and clean around the area. This would be a good time to replace the wheel bearing too since you have access to them and there not that expensive. Install the new bearing and seal, note make sure you oiled the bearing and seal before installing it back and take care when installing the axle back in and "C: clip. Use RTV silicon gasket maker to seal the differential cover and wheels back on and lower. If your lazy like i am, you can drain the differential fluid and replace it with a 50/50 mix with gear oil and Lucas engine oil additives. That may stop the leak and get you a few more miles. You gear oil is (ford 75W-140) (Dana 80W-90)and the capacity is 2.6 liters and 3.5 liters if you have the 10.25 Ring gear. Good luck and hope this helps.

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.

ya...
1 more way is ther but takes time ,quit more.

try to weld front differential where oil is gonna leak & but do this when your all oil is out of differential case than it will happen baater so,

another way is 1 solution which is highly recommanded for this type of crack in differentials,which still i cant get that name but at branded service center they will do for your differentials case.

THNX