How to Change the Transmission Fluid in a 2002 Mercury Mountaineer

by Kevin MclainUpdated November 07, 2017

Items you will need

  • Fluid catch pan

  • 1/2-inch drive ratchet

  • 22-millimeter socket

  • TX-30 Torx bit socket

  • Hand-held fluid pump

  • Mercon automatic transmission fluid

The 2002 Mercury Mountaineer comes with a transmission that does not have a dipstick. The fluid inside of the transmission protects all of the moving gears and seals. The transmission fluid bonds to the gears to prevent heat friction. The transmission fluid also bonds to the seals to keep the seals soft and flexible to prevent leaking. The fluid is only designed to last around 75,000 to 100,000 miles before it begins to breakdown. Change the transmission fluid between these intervals for maximum transmission performance and protection.

Park the 2002 Mercury Mountaineer on a level location and set the emergency brake.

Crawl under the driver side of the Mountaineer and locate the two-part drain plug on the bottom side of the transmission pan. The hex head drain plug has a smaller Torx plug in the center of the big plug. Place the fluid catch pan under the area of the drain plug.

Loosen the hex head drain plug by turning it counter clockwise with the ratchet and a 22-millimeter socket. Finish unscrewing the drain plug with your fingers until the transmission fluid begins to run out. Do not remove the plug, just loosen it up enough for the transmission fluid to drain out. Once all of the fluid has drained out from around the plug, tighten the plug with the ratchet and the 22-millimeter socket.

Unscrew the Torx plug by turning it counter clockwise with the ratchet and the TX-30 Torx bit until the plug is loose. Finish removing the plug completely from the transmission pan with your fingers. Set the Torx plug in a safe area near where you are working.

Insert the end of the small plastic hose into the center Torx plug hole. Pump the Mercon automatic transmission fluid into the pan with the fluid pump until the fluid begins to flow out of the fill hole. Remove the tube from the fill hole. Crank the engine and shift the transmission gear lever throughout all of the gears and then back into park.

Inspect the fluid level inside of the Torx plug hole. If the fluid has stopped flowing out of the Torx fill hole, insert the plastic tube back into the fill hole and continue to pump the Mercon fluid into the transmission pan until the fluid flows out of the hole again. Screw the Torx plug back in and tighten down with the ratchet and Torx socket. Remove the drip pan out from under the 2002 Mercury Mountaineer.


The purpose of cranking the engine and shifting through all of the gears is to get the transmission fluid into all areas of the transmission. This will most likely lower the fluid level at the Torx fill hole, thus the need to refill the transmission pan with more fluid.

A hand-held fluid pump or a squeeze bottle of the Mercon automatic transmission fluid can be bought at most any auto parts store.


Use caution when working around a hot transmission and hot transmission fluid to prevent serious burns to your skin.

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