1991 1999 ford explorer chilton User Manual

							Make sure the transmission is in P(A/T) or in gear on a manual, then FIRMLY set the parking brake
and block the drive wheels.
1. 
Check under the vehicle to see if there is sufficient clearance for you to access the filler plug on the
side of the differential housing. If not you will have to raise and support the vehicle using jackstands
at four points to make sure it is completely level. Failure to support the vehicle level will prevent from
properly checking or filling the drive axle fluid.
2. 
Thoroughly clean the area surrounding the fill plug. This will prevent any dirt from entering the
housing and contaminating the gear oil.
3. 
To check the rear drive axle fluid level, loosen the fill plug ...... then remove it. Fluid should trickle out of the hole HOW TO USE THIS BOOK
LEVEL CHECK 127 
						

							If necessary, add the proper grade of lubricant until fluid trickles out
Remove the fill plug and make sure that the gear oil is up to the bottom of the fill hole. If a slight
amount of lubricant does not drip out of the hole when the plug is removed, additional lubricant
should be added. Use hypoid gear lubricant SAE 80 or 90.
4. 
If the differential is a Traction-Lok limited-slip unit, be sure to use 4 oz. of Ford Friction Modifier
C8AZ-19B546-A or equivalent special limited-slip additive with the lubricant.
Once you are finished, install the fill plug, then (if raised) remove the jackstands and lower the
vehicle.
5. 
DRAIN & REFILL
Drain and refill the drive axle housings every 100,000 miles (160,000 km) or any time the vehicle is driven in
high water (up to the axle). Although some fluid can be removed using a suction gun, the best method is to
remove the axle housing cover (if equipped) to ensure that all of any present contaminants are removed. As
with any fluid change, the oil should be at normal operating temperature to assure the best flow and removal
of fluid/contaminants.
Most front and some rear drive axle assemblies do not have a removable cover for fluid draining.
However, these units may have a drain plug instead. Drain plug equipped drive axles can be serviced in
the same manner as the manual transmission and/or transfer case. If no drain plug is found, you will
need to use a suction gun through the fill hole to remove the fluid. The procedure below is for housing
cover equipped axles.
Drive the vehicle until the lubricant reaches normal operating temperature.
1. 
If necessary for access, raise and support the vehicle safely using jackstands, but be sure that the
vehicle is level so you can properly refill the axle when you are finished.
2. 
If a suction gun is used to drain the fluid, remove the fill plug and insert the suction tube into the fill
hole until it rests at the lowest most point inside the housing. Operate the suction gun as per the
manufacturers directions. When the fluid is completely removed, skip to the differential filling
procedure. HOW TO USE THIS BOOK
128 DRAIN & REFILL 
						

							Remove the fill plug, then clean the area around the axle housing cover to prevent dirt from
entering it
Use a wire brush to clean the area around the differential. This will help prevent dirt from
contaminating the differential housing while the cover is removed.
3. 
Position a drain pan under the drive axle.
4. 
Loosen and remove all but two of the cover retaining bolts. Dont lose the axle identification tagLoosen and remove all but 2 of the housing covers upper or side retaining bolts. The remaining 2
bolts should then be loosened to within a few turns of complete removal. Use a small prytool to
carefully break the gasket seal at the base of the cover and allow the lubricant to drain. Be VERY
careful not to force or damage the cover and gasket mating surface.
5.  HOW TO USE THIS BOOK
DRAIN & REFILL 129 
						

							With the remaining bolts loose, carefully pry out on the cover (to break the seal) and allow the
fluid to drain
Once most of the fluid has drained, remove the remaining bolts and pull the cover from the housing
Once most of the fluid has drained, remove the final retaining bolts and separate the cover from the
housing.
6.  HOW TO USE THIS BOOK
130 DRAIN & REFILL 
						

							
To fill the differential:
Carefully clean the gasket mating surfaces of the cover and axle housing of any remaining gasket or
sealer. A putty knife is a good tool to use for this. You may want to cover the differential gears using
a rag or piece of plastic to prevent contaminating them with dirt or pieces of the old gasket.
7. 
Remove any old gasket material from the sealing surfaces then clean them of any residual oil
Install the housing cover using a new gasket and sealant. Tighten the retaining bolts using a crisscross
pattern.
8. 
Make sure the vehicle is level before attempting to add fluid to the drive axle, otherwise an incorrect
fluid level will result.
Refill the drive axle housing using the proper grade and quantity of lubricant. Install the filler plug,
operate the vehicle and check for any leaks.
9. 
Cooling System CAUTION
Never remove the radiator cap under any conditions while the engine is running! Failure to follow these
instructions could result in damage to the cooling system and/or personal injury. To avoid having scalding hot
coolant or steam blow out of the radiator, use extreme care when removing the radiator cap from a hot
radiator. Wait until the engine has cooled, then wrap a thick cloth around the radiator cap and turn it slowly to
the first stop. Step back while the pressure is released from the cooling system. When you are sure the
pressure has been released, press down on the radiator cap (with the cloth still in position), turn and remove
the cap. HOW TO USE THIS BOOK
Cooling System 131 
						

							Cut-away view of a typical cooling system flow
Click to enlarge
FLUID RECOMMENDATIONS
The recommended coolant for all vehicles covered by this manual is a 50/50 mixture of ethylene glycol and
water for year-round use. Choose an aluminum compatible, good quality antifreeze with water pump
lubricants, rust inhibitors and other corrosion inhibitors along with acid neutralizers.
INSPECTION
Any time you have the hood open, glance at the coolant recovery tank to make sure it is properly filled. Top
of the cooling system using the recovery tank and its markings as a guideline. If you top off the system, make
a note of it to check again soon. A coolant level that consistently drops is usually a sign of a small, hard to
detect leak, though in the worst case it could be a sign of an internal engine leak (blown head gasket/cracked
block? ... check the engine oil for coolant contamination). In most cases, you will be able to trace the leak to a
loose fitting or damaged hose (and you might solve a problem before it leaves you stranded). Evaporating
ethylene glycol antifreeze will leave small, white (salt like) deposits, which can be helpful in tracing a leak. HOW TO USE THIS BOOK
132 FLUID RECOMMENDATIONS 
						

							
Common cooling system components found on all models (not shown is the water pump)-3.0L equipped ranger shown, other
models are similar
Click to enlarge
To add coolant, remove the lid from the coolant recovery tank ... HOW TO USE THIS BOOK
INSPECTION 133 
						

							... then add enough coolant to attain the proper level as indicated on the tank. Use a funnel to
avoid spills
At least annually or every 12,000 miles (19,000 km), all hoses, fittings and cooling system connections should
be inspected for damage, wear or leaks. Hose clamps should be checked for tightness, and soft or cracked
hoses should be replaced. Damp spots, or accumulations of rust or dye near hoses or fittings indicate possible
leakage. These must be corrected before filling the system with fresh coolant. The pressure cap should be
examined for signs of deterioration and aging. The fan belt and/or other drive belt(s) should be inspected and
adjusted to the proper tension. Refer to the information on drive belts found earlier in this section.
Finally, if everything looks good, obtain an antifreeze/coolant testing hydrometer in order to check the freeze
and boil-over protection capabilities of the coolant currently in your engine. Old or improperly mixed coolant
should be replaced.
Checking antifreeze protection with an inexpensive testerCAUTION
When draining coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze, and are
likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in
sufficient quantity. Always drain coolant into a sealable container. Coolant may be reused unless it is HOW TO USE THIS BOOK
134 INSPECTION 
						

							
contaminated or several years old.
At least once every 3 years or 36,000 miles (48,000 km), the engine cooling system should be inspected,
flushed and refilled with fresh coolant. If the coolant is left in the system too long, it loses its ability to prevent
rust and corrosion. If the coolant has too much water, it wont protect against freezing.
If you experience problems with your cooling system, such as overheating or boiling-over, check the simple
before expecting the complicated. Make sure the system can fully pressurize (are all the connections tight/is
the radiator cap on properly, is the cap seal intact?). Ideally, a pressure tester should be connected to the
radiator opening and the system should be pressurized and inspected for leaks. If no obvious problems are
found, use a hydrometer antifreeze/coolant tester (available at most automotive supply stores) to check the
condition and concentration of the antifreeze in your cooling system. Excessively old coolant or the wrong
proportions of water and coolant will hurt the coolants boiling and freezing points.
Check the Radiator Cap
While you are checking the coolant level, check the radiator cap for a worn or cracked gasket. If the cap
doesnt seal properly, fluid will be lost and the engine will overheat. Worn caps should be replaced with new
ones.
Be sure the rubber gasket on the radiator cap has a tight seal
Clean Radiator of Debris
Periodically, clean any debris-leaves, paper, insects, etc.- from the radiator fins. Pick the large pieces off by
hand. The smaller pieces can be washed away with water pressure from a hose. HOW TO USE THIS BOOK
INSPECTION 135 
						

							Periodically remove all debris from the radiator fins
Carefully straighten any bent radiator fins with a pair of needle-nosed pliers. Be careful; the fins are very soft.
Dont wiggle the fins back and forth too much. Straighten them once and try not to move them again.
DRAINING, FLUSHING & REFILLING CAUTION
When draining coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze, and are
likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in
sufficient quantity. Always drain coolant into a sealable container. Coolant may be reused unless it is
contaminated or several years old.
A complete drain and refill of the cooling system at least every 30,000 miles (48,000 km) or 3 years will
remove the accumulated rust, scale and other deposits. The recommended coolant for most late model cars is a
50/50 mixture of ethylene glycol and water for year-round use. Choose a good quality antifreeze with water
pump lubricants, rust inhibitors and other corrosion inhibitors along with acid neutralizers.
Before opening the radiator petcock, spray it with some penetrating lubricant. HOW TO USE THIS BOOK
136 DRAINING, FLUSHING & REFILLING