Transmission Fluid and Filter change

By: John Gislason (99NDP71)

This is a general procedure for changing the fluid and filter in your transmission, it is not intended to be all encompassing, but rather a general outline of what is involved.

Before you begin, I will assume that the existing fluid is NOT brownish in color, and that it does not smell burned, if it is/does, then changing it now may cause even more trouble.

You will need the following items:

-Jack and jack stands

-Shop rags or towels

-Set of wrenches (std & metric)

-10mm socket wrench for pan bolts (1/4” drive preffered)

-7/16” socket (for converter drain)

-Large std. screwdriver 14” to 18” long is best

-14 qts. ATF (Mercon V is recomended)

-One drain pan, capacity at least 12 qts.

-Two lengths of small hose, 5/16” x 4’ ea. (I use clear plastic)

-One gallon windshield wash or milk jug (used, need not be clean)

-One can of brake cleaner

-New filter kit (if replacing filter, optional for most ppl)

Removing the old fluid

First disconnect BOTH cooler lines at the radiator pre’98, or at the cooler ‘98 and newer. Push one of the small hoses onto each line at the fitting, make sure they go on about 1”. Now run both hoses into the empty jug, and set it inside the right inner fender on top of the upper control arm. You are ready to start the engine and use the transmission to pump out the old fluid, and flush the system.

Be CAREFUL, you will most likely get more than one gallon (4 qts.) of fluid out doing this, so when the jug is just over half full, shut the engine off and empty the jug, then put it back and finish flushing. Pay attention to witch hose the fluid comes out of so you can purge all the old fluid out when the job is nearly done.

Draining the converter

Now that the pan is empty, it is a perfect time to drain the converter, and service the filter (if you are doing that).

Set the parking brake, chalk the rear wheels front and back sides, jack up the car under the large front cross-member, and place jack-stands securely under the vehicle on the frame.

To drain the converter, remove the 2” rubber plug from the bottom of the bell housing, and using a large standard screwdriver turn the engine over by prying against the converter shell (either way is ok). When you can see the small plug in the access hole, use your 7/16” socket to loosen the plug and allow the converter to drain. It will hold between 6 and 8 qts., and may take up to an hour to drain completely, so be prepared.

While the converter is draining, you can remove the pan bolts and pan from the transmission and service the filter. There will be a small quantity of ATF left in the pan, so use caution, but it will not be full. Change the filter, and clean the pan throughly. You can place the pan in your dishwasher after wiping it out to make sure it is clean, but make sure there are no women around to see this! The factory pan gasket is a “rubber” covered metal core gasket, and if still there, reusable unless torn or chunks are missing.

After installing the new filter (make darn sure the old “o”-ring came out of the transmission with the old filter), you are ready to re-install the pan and gasket. Set the gasket on the pan lip, and using two bolts set the pan into position and hold it in place using one on either side at opposite corners, finger tight! Now loosely install the remaining pan bolts into the transmission. Once all bolts are installed, working in a cris-cross pattern, torque the bolts to 9-11 ft-lbs. (snug).

Reinstall the torque converter drain plug, and torque to 9-11 ft-lbs. (snug). You are ready to set the vehicle back onto the ground at this point.

Refill and flush

After the vehicle is back onto the ground, once again dump out the old ATF from the jug under the hood. Add approximatly 4 qts. of ATF to the transmission through the fill tube. Start the engine, and allow it to run until the jug is about half full, you have now flushed the system. It is possible to also flush the cooler, but that requires a small section of cooler line be attached to the cooler outlet, and the “to cooler” line be re-attached to the cooler and most people do not have the “special” small line available, and you just did a far better service than 99% of all vehicles will ever get anyway.

Reconnect both steel cooler lines to the cooler assembly and tighten the tube nuts securely (snug), DO NOT overtighten! It is FAR better to add torque to the nut if it seeps, than to strip it out and have to have it towed for repairs, yes?

To complete the refill process, start the engine and allow it to idle as you add an additional 6 qts of ATF through the fill tube. Operate the selector through each range, and return it to park and set the parking brake. When all 10 qts (4+6) are in, and with the engine running at idle still, check the level and add until it appears on the bottom end of the band. Now take it out for a drive. When you get back, verify that the fluid is in the “HOT” operating range, add as required.

Good luck, and congratulations on the completion of another DIY project!