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F150 Transmission Oil & Filter Change

Work performed on a 1998 Ford F150 4x4 with 4.6L V-8, 4R70W 4spd electronic automatic (code U in doorjamb). This tech article was originally posted at It is primarily intended for Ford trucks but most likely also applies to other Ford models.

Follow these instructions at your own risk.

Tools needed for the job:

Note: wear safety glasses while under the vehicle for eye protection as there's lots of dirt and grime under there just waiting to drop into your eyes.


Here's a picture of the Ford 4R70W transmission pan with the gasket sitting on top. The OE gasket is re-usable and is stamped as such shown by the red arrow on the right side of the picture below. Notice the grey colour donut magnet shown by the arrow on the top left of the picture.

Photo of 4R70W transmission pan removed

  1. Wait until the vehicle has cooled off for at least 1/2hr if you've just driven it to avoid getting a "hot oil treatment"... burns hurt!
  2. Remove the rubber inspection grommet (1 1/2inch diameter) between the engine and the transmission in the bottom of the bell housing. Use a flathead screwdriver to pry it out - not difficult.
  3. With an assistant under the vehicle looking into the inspection hole with a flashlight or worklight, use the 18mm socket & wrench to turn the crankshaft pulley (by the radiator) to turn the engine (clockwise). In the inspection hole you will see the torque converter. Have your assistant stop you turning the engine when the 11mm drain bolt is visible in the torque converter. You can do the procedure yourself but it is a lot of climbing under the vehicle and back to turning the crank pulley until you find the plug.
  4. Place your drain pan under the inspection hole and remove the drain plug out of the torque converter with an 11mm socket and extension. The oil will pour out slowly... in fact it may take a couple hours to fully drain the torque converter. It is estimated that it holds almost half of the transmission fluid capacity or around 6 quarts.
  5. Replace the drain plug and tighten securely but do not over-tighten. Some people like to use locktite on the threads to prevent it coming out. This is difficult unless you let it drain overnight so you can clean off the plug and dry off the threads in the torque converter. If fluid is still dripping out it will be difficult. It's optional! Ok, then after tightening the plug, replace the inspection cover.
  6. Loosen all the bolts holding the transmission oil pan on. Carefully remove the bolts by one corner of the pan. Carefully pry the pan down at that corner with your drain pan underneath. There will be fluid going everywhere. Try to get a drain pan that is at least 18 inches wide.
  7. Keep removing the other bolts but leave them loose on one edge to hold the pan up. Tilt it more to get more oil out. Once half of the oil is drained hold the pan back up with an assistant if you have one and remove the rest of the bolts while your assistant holds the pan up. Then carefully drop the pan (without spilling fluid all over yourself) into your drain pan. Drain it.
  8. Using rags or paper towels and solvent clean the interior of the pan and carefully remove the sludge from the pan magnet at the bottom. There is a metallic film on most of the pan surfaces that will wipe off.
  9. Note the position of the OE filter, pull it off and replace it with the new one, make sure the old rubber seal comes out too. Pop the new filter in place of the old one in the same position. Use clean rags to clean the gasket mating surfaces on the pan and the transmission. The old gasket is re-usable. Place the pan back up onto the transmission. Hand-tighten all the bolts.
  10. If you have a torque wrench use it to make sure you don't over-tighten the bolts.
  11. Using a long funnel fill about 5-6 quarts into the transmission through the dipstick tube. You'll need a small neck funnel.
  12. Start the engine and run it for 30 seconds.
  13. Fill another 4 or 5 quarts.
  14. Start the engine again and run 30 seconds.
  15. Inspect level with the dipstick.
  16. Fill more oil up to "full" mark on dipstick.
  17. Drive it around the block and again check the oil level.

You're done.

There will remain about 1 or 1 1/2 quarts in the oil cooler and hoses which can be blown out with compressed air if you so desire but the hoses will have to be removed so most people don't bother. It's also difficult if you don't have compressed air handy.

When you start the engine the hydraulic pump in the transmission fills up the torque converter. You don't want to overfill the transmission right away as 13 quarts won't fit in it while the engine is stopped because the torque converter is empty to start with, that's why you have to start it up a couple of times, otherwise you may blow oil out the vent tube and/or blow some seals.

If you accidentally overfill it, the easiest way to get some fluid out is to drain some from the torque converter. Then you won't have to touch the pan bolts.

Procedure on V-6 and EOD or 4R100 automatic transmission will differ slightly with different sized sockets and different oil. Check your transmission oil dipstick. Most Ford truck automatics went from Mercon to Mercon V during the 1998 model year. Early models got Mercon and the corresponding dipstick. Apparently Mercon V can be run in a Mercon transmission but don't run Mercon in a Mercon V transmission.

If you find a little plastic plug with a rubber o-ring, don't worry, this was in the dipstick tube while the engine was assembled on the assembly line and falls into the transmission pan. It's not a broken or missing part! Discard it or keep it as a souvenir.

Mine took just a hair over 12 quarts. Capacity if the transmission oil cooler/lines where empty as well is listed at 13.5 quarts.

Cost (CDN$):

Many transmission shops do a "power" fluid change by hooking up to the cooler lines and doing a pressure fill/exchange without dropping the transmission oil pan. This isn't the best since you have old fluid mixing with new, and you haven't changed the filter. As well the magnet in the pan won't get a cleaning and won't work as effectively to catch metal sludge/particles out of the oil. Think of a power flush as taking a shower, then putting your dirty clothes back on. Not exactly ideal.

Do it yourself, then you'll know it has been done right!

This article has been generously donated by Peter Ferlow.