What is a pinion seal verses a rear main differential seal?

There are several seals for the differential. The pinion seal is towards the driveshaft. The rear cover is on the back of the differential.

The rear cover seal is a gasket and can be replaced by removing the rear cover and scraping off the old gasket. Some mechanics make their own gasket out of a liberal application of atv gasket compound. Other mechanics use a stamped gasket and may apply a small amount of cement to one side of the gasket to hold it to the cover.

The cover is bolted on by Torx head fittings.

The pinion seal is another matter. The driveshaft needs to come off. The flange needs to come away from the differential and the seal rides the shaft going into the differential. Some housings require a removal tool.

With either seal, you need to determine the type of differential you have. Limited -slip requires an additive to work in the standard lube. Some require only synthetic gear lube as well as the additive.

A cover gasket is not very hard to replace. The pinion seal can be more difficult. Price the repair.

Do not reuse the differential fluid.

There are two places it can leak from. The rear differential cover or the pinion seal at the front of the differential. Both are easy to replace. The pinion seal will require a little more labor than the differential cover plate. You will have to remove the drive line and then break the pinion nut loose. Use a good impact wrench for this and a six point socket for that step. Then you will need to remove the yoke from the pinion gear. Should be able to tap it off. If not use a puller. Remove the old pinion seal with a flat tip screw driver by driving it through the lip of the old seal and push the screwdriver to the side and it will pop out. Clean the hole for the new seal. install the new seal and the yoke. Tighten the pinion nut. You will need to get access to a manual to check the bearing preload on the pinion nut. Then use a torque wrench to check for correct bearing preload. Re-install the drive line.

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.

The fluid splattered all over is most likely coming from the pinion seal. (The seal at the front of the differential where the driveshaft yoke goes in.) Normally, you would remove the driveshaft and the pinion yoke to relace the seal. The grinding however, leads me to believe that the seal leaking is a RESULT not a CAUSE of your problem. The way you describe it sounds like you may have some serious pinion and/or ring gear damage inside the differential.
If this is the case, there are severl ways to go about repairing this. You could tear your differential apart and replace the defective/damaged parts inside. You could replace your differential with a used one from a salvage yard. You could replace your differential with a remanufactured differential assembly.

To check for damage, remove the rear cover from the differential and check for metal in the oil and in the bottom of the housing. You can also turn the ring gear around and check for broken teeth. You can also inspect the spider gears and pinion gear for damage.

i assume that you are talking about the seal at the front of the differential were the drive shaft bolts to the flange,if so this is called the front differential pinion seal,if your talking about the differential cover at the back of the differential(most rearward part of the rear end) this is called the differential cover gasket.

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

PINION FLANGE & OIL SEAL

CAUTION: Following procedure must be used to retain proper pinion bearing preload. Failure to follow procedure may result in premature axle assembly or component failure. Ensure pinion bearing preload is checked before disassembly, as previous pinion bearing preload will be used during reassembly.

Removal

1. Raise and support vehicle. Scribe reference mark on drive shaft-to-pinion flange on differential for reassembly reference. Remove bolts and "U" joint straps at pinion flange on differential.
Disconnect drive shaft from differential.
2. Remove rear wheels and brake drums to prevent any drag that may affect pinion bearing preload reading. Using INCH-lb. torque wrench, measure amount of force required to rotate pinion. This is pinion bearing preload. Record pinion bearing preload for reassembly reference.
3. Using Holder (6719), hold pinion flange. Remove pinion nut and washer. Scribe reference mark on pinion flange-to-pinion for reassembly reference. Using appropriate puller, remove pinion flange from pinion. Remove oil seal from axle housing.

Installation

1. Ensure oil seal surface in axle housing is clean. Coat lip of oil seal with gear lube. Install oil seal using appropriate seal installer. Drive oil seal into axle housing until oil seal installer contacts axle housing.
2. Install pinion flange on pinion with reference mark aligned. Using appropriate pinion flange installer, install pinion flange on pinion.

CAUTION: Washer must be installed on pinion with convex side of washer facing outward (away from pinion).

3. Install washer on pinion with convex side of washer facing outward (away from pinion). Install NEW pinion nut. Tighten pinion nut to 210 ft. lbs. (285 N.m). Rotate pinion several times to seat pinion bearings.

CAUTION: DO NOT overtighten or loosen then retighten pinion nut when adjusting pinion bearing preload. If pinion nut is overtightened, collapsible spacer on pinion must be replaced.

4. Rotate pinion using INCH-lb. torque wrench. Rotating torque should be equal to reading recorded in removal step 2) , plus 5 INCH lbs. (.056 N.m). If rotating torque is low, tighten pinion nut in small increments until proper rotating torque is obtained.
5. To install remaining components, reverse removal procedure using NEW "U" joint straps and bolts. Ensure all reference marks are aligned. Tighten bolts to specification. Check lubricant level and add if necessary.

Section 05-02A: Axle, Integral Carrier — 8.8-Inch Ring Gear 1994 Town Car, Crown Victoria/Grand Marquis. Workshop Manual REMOVAL AND INSTALLATION Axle Shaft NOTE: Whenever replacing the rear axle lubricant, use Rear Axle Lubricant XY-90-QL (ESP-M2C154-A) or equivalent.
Removal
CAUTION: The rear brake anti-lock sensor must be removed before the axle shafts are removed. The rear brake anti-lock sensor is bolted on the rear disc brake caliper anchor plate.

1. Raise vehicle to desired working height. Refer to Section 00-02 . Remove rear wheel (1007) and tire assembly. Remove rear disc brake calipers (2552) and rear disc brake rotors (2C026) .
   
   
   
   
   

1. Clean all dirt from area of axle housing cover with a wire brush and/or cloth.

1. Drain rear axle lubricant by removing the axle housing cover .

1. Remove differential pinion shaft lock pin and differential pinion shaft .
   
   
   
   

1. Push flanged end of the axle shafts toward the center of the vehicle and remove the rear axle shaft retaining u-washer from the button end of the axle shaft .
   
   
   
   

1. Remove axle shaft from the rear axle housing , being careful not to damage the inner wheel bearing oil seal (1177) and rear brake anti-lock sensor ring.

Installation
NOTE: Check for presence of rear axle shaft o-ring (4A332) on the spline end of the shaft and install if not present.
CAUTION: Care must be taken not to let axle shaft splines damage oil seal or bearing assembly.

1. Carefully slide axle shaft into rear axle housing without damaging rear wheel bearing (1225) or rear brake anti-lock sensor indicator (2C189) . Start splines into side gear and push firmly until the button end of axle shaft can be seen in the differential case .

1. Install the rear axle shaft retaining u-washer on the button end of the axle shaft splines, then pull the shaft outboard until the shaft splines engage and the rear axle shaft retaining u-washer seats in the counterbore of the differential side gear .

1. Position the differential pinion shaft through the differential case and differential pinion gears , aligning the hole in the differential pinion shaft with the lock bolt hole. Apply Rear Axle Lubricant to differential pinion shaft lock pin . Install differential pinion shaft lock pin and tighten to 20-41 Nm (15-30 lb-ft). CAUTION: Differential pinion shaft lock pin must be tightened to specification using Stud and Bearing Mount E0AZ-19554-BA (WSK-M2G349-A1) or equivalent.
   
   
   
   
   NOTE: Axle housing cover must be installed within 15 minutes of application of the silicone rubber or new silicone rubber must be applied.
   CAUTION: Make sure machined surfaces on both axle housing cover and rear axle housing are clean before installing the new silicone sealant. Inside of axle must be covered when cleaning the machined surface to prevent axle contamination. Tighten the cover bolts in a crosswise pattern to ensure uniform draw on axle housing cover .
   

1. Apply Silicone Rubber D6AZ-19562-AA or BA (ESB-M4G92-A or ESE-M4G195-A) or equivalent. Install axle housing cover and tighten retaining bolts to 28-38 Nm (38-52 lb-ft).
   
   
   
   

1. Add Motorcraft Rear Axle Lubricant XY-90-QL or KL (ESP-M2C154-A) or equivalent until it is 6-14mm (1/4-9/16 inch) below bottom of fill hole. Add 118.3 mL (4 oz) of Ford Additive Friction Modifier C8AZ-19B546-A (EST-M2C118-A) or equivalent to Traction-Lok axles. Install fill plug and tighten to 20-41 Nm (15-30 lb-ft).

1. Install rear brake anti-lock sensor indicator . Tighten retaining bolt to 4.5-6.8 Nm (40-60 lb-in).

1. Install rear disc brake caliper and rear disc brake rotor .

1. Install wheels and tires.

---------------------------------------------------------

1. Insert Rear Bearing Remover T85L-1225-AH in bore and position it behind bearing so tangs on tool engage bearing outer race. Remove rear wheel bearing and inner wheel bearing oil seal as a unit, using Impact Slide Hammer T50T-100-A.
   
   Rear Disc Brake Caliper Anchor Plate
   
   
   
   
   

1. Lubricate the rear wheel bearing with Rear Axle Lubricant.
   
   
   
   

1. Install rear wheel bearing into the housing bore using Axle Tube Bearing Replacer T78P-1225-A.
   
   
   
   CAUTION: Installation of rear wheel bearing or inner wheel bearing oil seal assembly without proper tool may result in an early bearing or seal failure. If inner wheel bearing oil seal becomes cocked in bore during installation, remove it and install a new one.
   

1. Install the inner wheel bearing oil seal using Axle Tube Seal Replacer T78P-1177-A. Use Premium Long-Life Grease XG-1-C or K (ESA-M1C75-B) or equivalent between the lips of the inner wheel bearing oil seal .
   
   
   
   

1. Install axle shafts as outlined.

SECTION 205-02B: Rear Drive Axle/Differential — Ford 8.8-Inch Ring Gear 2003 Mustang Workshop Manual IN-VEHICLE REPAIR 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 rear brake disc (2C026). For additional information, refer to Section 206-04 .

1. Remove the differential housing cover (4033) and drain the lubricant. For additional information, refer to Differential Housing Cover in this section.

1. Remove the differential pinion shaft (4211).
   1. Remove the differential pinion shaft lock bolt (4241).
   1. Remove the differential pinion shaft.

1. CAUTION: Do not damage the rubber O-ring in the axle shaft groove.
   Remove the U-washer (4N237).
   1. Push the axle shafts (4234) inboard.
   1. Remove the U-washer.

1. CAUTION: Damage to the rear brake anti-lock sensor (2C190) may occur if it is not removed before the axle shaft.
   Carefully remove the rear brake anti-lock sensor. For additional information, refer to Section 206-09A .

1. CAUTION: Do not damage the wheel bearing oil seal.
   Remove the axle shaft.

--------------------------------------------------------------------------------------
Rear Wheel Bearing and Axle Shaft Oil Seal Removal

1. Remove the axle shaft (4234). For additional information, refer to Axle Shaft in this section.

1. NOTE: If the wheel bearing oil seal is leaking, the axle housing vent may be plugged.
   Using the special tools, remove the rear wheel bearing and wheel bearing oil seal.

Installation

1. Lubricate the new rear wheel bearing with the specified lubricant.

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

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

-------------------------------------------------------------------
Installation

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

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

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

1. NOTE: If a new pinion shaft lock bolt is unavailable, coat the threads with Threadlock and Sealer EOAZ-19554-AA or equivalent meeting Ford specification WSK-M2G351-A5 prior to installation.
   Install the differential pinion shaft.
   1. Align the hole in the differential pinion shaft with the case lock bolt hole.
   1. Install a new differential pinion shaft lock bolt.

1. Install the differential housing cover and fill the rear axle with the specified lubrication. For additional information, refer to Differential Housing Cover in this section.

1. Install the rear brake anti-lock sensor. For additional information, refer to Section 206-09A .

1. Install the rear brakes. For additional information, refer to Section 206-04 .

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

1. Lower the vehicle.

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.

-----------------------------------------------------------------------------------------------------------------
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.