SAAB Tech—Automatic Transmission Complete Fluid Change

It's always a good idea to change your automatic transmission fluid regularly to prolong the life of your c900's auto trans. SAAB recommends a fluid change every 30,000 miles under normal driving conditions—15,000 miles under severe conditions. Simply opening the drain plug on the sump pan only gets about 3 or 4 quarts of the fluid out of the transmission. The torque convertor, valve bodies, and transmission cooler will still be full of old, worn fluid. The following technique will flush ALL the old fluid out of the transmission.

A simple drain and flush is demonstrated. You may opt to drop the sump pan and remove and clean the filter and magnet as well. If you remove the filter for cleaning or replacement, BE SURE TO REINSTALL THE SEAL (part #9317348). A worn or missing seal will cause the transmission to suck air and skip—especially on left turns. Be sure to note the location of the magnet on the sump pan and reinstall it in the same place. To do a band adjustment or to clean the governor, you will need to remove the rear pan as well. If you plan to remove the pans, be sure to order the correct gaskets prior to starting the job. Instructions are in the Bentley manual. Always thouroughly clean the area around the pans BEFORE removing them so as not to contaminate the area once the pans are off.

I run Amsoil SuperShift ATF in my SAAB automatic transmissions. It is a synthetic fluid and is compatible with the OEM spec Ford type F fluid.

The T37 automatic uses 8.5 quarts of fluid. You will need at least 2 extra quarts to use this technique—3 or 4 extra would be better. I usually just buy a case (12 quarts).


Up on stands

1. Park the car on a level surface. Insert the special SAAB spacer tool (or a home-made spacer) under the upper control arms and raise and support the car so both front wheels are off the ground. Apply the park brake and block the rear wheels.

Skid plate

2. If your transmission sump pan has a plug (normal), you can access it through the opening in the skid plate. If it does not, you will have to remove the skid plate and drop the sump pan. The skid plate is attached with 3 12mm bolts and 2 13mm nuts. The sump pan is secured with 12 10mm bolts.

under the car

3. This view is under the skid plate. As you can see, the drain plug generally has a large screw head. On the driver's side (LHD) of the transmission is the return line from the transmission cooler. The crankcase oil dran plug is also visible.

return hose, dirty

4. This area can get pretty crudded up. Get some aerosol parts cleaner or put some kerosene in a spray bottle and clean the area very well. You'll be removing parts, and you don't want the transmission internals to get contaminated.

Clean area

5. Here's the same area after cleaning. Note, that there is a fitting in the transmission and a banjo bolt on the line that screws into that fitting.

Special tool

6. Here is a special tool I made to remove and install the transmission sump drain plug. Just a piece of flat steel that I bent and ground down to fit the plug.

Using special tool

7. Using the special tool to remove the sump plug.


8. Draining the sump into an open container. Use an open container so that you can measure how much fluid came out. (It doesn't have to be one of your wife's good pans.)

Sump plug

9. The sump plug has a fiber or other sealing washer. Be sure to replace it with a new one. Reinstall the plug.


10. Measure how much fluid came out of the sump. Generally it will be between 3 and 4 quarts.


11. Add the same amount of clean fluid as you removed from the sump. Use a clean funnel inserted into the transmission dipstick tube.


12. For the next step, you will need a large open container. Mark the inside of the container in 1 quart incriments with a sharpie. I mark 10 quarts. I just kept filling the bucket with water a quart at a time and marking each quart line as I filled it up.

Remove banjo

13. Place a 7/8" wrench on the fitting in the transmission and a 19mm wrench on the cooler line banjo bolt and loosen the banjo bolt.

Drain plug

14. You will need to plug the fitting in the transmission once you remove the banjo bolt. I use an extra oil drain plug which has the same thread and pitch.

Plug inserted

15. Banjo bolt and transmission cooler line removed and oil drain plug inserted in its place.

Vinyl hose

16. You will need a length of clear vinyl 3/8" ID hose at least 2' long, and a hose clamp.

Hose on banjo bolt

17. The banjo bolt should thread snugly into the end of the hose. Screw it in and tighten the worm clamp.

Hose in bucket

18. Snake the other end into the bucket and hold it in place with duct tape or a clamp. Situate the bucket and the markings so that you can see them from the driver's seat.

Plug inserted

19. Sit in the driver's seat. APPLY THE BRAKE. Start the car and put the gear selector in drive, then take your foot off the brake. Once 1 quart of fluid has pumped into the bucket, APPLY THE BRAKE, put the car in park and shut the engine off.

Vinyl hose

20. Add 1 quart of clean fluid to the transmission.

Repeat steps 19 and 20 pumping and refilling 1 quart at a time and running the transmission alternately through D, 1, 2 and R until the fluid running through the vinyl tube runs clear red (clean fluid). To insure that you don't overfill the transmission, only pour 1/2 quart in on the last pour.

Disconnect the vinyl tube from the banjo bolt; Install new seals on the banjo bolt; and reinstall it on the transmission.

Lower the car onto level ground and start the engine. Allow it to reach operating temperature (when the fans come on). Be sure the park brake is set and that the rear wheels are blocked. Put the car in neutral—engine still running—and check the level on the dipstick. Add fluid to reach the appropriate level.