Member
Hello friends. I recently change out my leaking transmission oil cooler lines. I will share the process since I used to think the subframe would have to be lowered when a fellow user told me that, but it is simply not true and quite manageable.
Tools required:
8 mm wrench (socket preferred)
13 mm wrench (socket w/ extension)
19 mm wrench (socket preferred)
24 mm wrench (socket preferred)
Laser 7263 Disconnect Tool
Tiny flat head screwdriver
Medium flat head screwdriver
Empty bucket or drain to catch coolant
Cardboard or creeper
Light source
Parts required:
Transmission oil cooler lines: Part#17221711465 and 17221711464
Transmission oil cooler o-rings x2 (Buy 6 to be safe since they are thin): Part#17211742636
Transmission oil cooler regulator o-rings x3 (Buy 6 to be safe): Part#17111711987
Optional: transmission oil cooler (Do not use the o-rings that they provide, since they are too big and can crack the oil cooler plastic regulator): Part#17217505823
Optional: Transmission oil cooler regulator: Part#17211437772
Step 1: Remove the undertray. I am not sure what the size of the screws are that hold it into place since my car hasn't had an undertray for 2 years since I've been too busy working on it.
Step 2: Jack car up from LHD side. Put wheel blocks and a safety jack below as well if you value life or your wife knows you have life insurance.
Step 3: Remove left front wheel.
Step 4: Unscrew the bolts holding the fender liner into place. I would put masking tape on the edge of the fender to prevent paint from being scratched. You can just do the front half and leave the rear half alone. For me, my sizes were 8mm. When removed fold the front half and put it behind the rear of the caliper for more access.
Step 5: Remove the lower plastic that clips in between the front bumper and fender line. It is held on by two 8 mm screws. You need to push the front two tabs in and slide towards the rear of the car and wiggle it out towards the left while pushing the right big clip down.
Step 6: Unscrew the two screws holding in the brake duct cooler. They are on the top. Once removed, wiggle it out gently.
Step 7: You now have access to the whole transmission cooler. First thing I did was go below the cooler and disconnect the lower two lines that go into the bottom of the cooler. You need to use the special disconnect tool, 7263 laser disconnect tool you can find on amazon. It is a red metallic tool. Apply pressure to the tool and slide the tube out. Make sure to put a drain below to catch the transmission oil from dripping.
Attachment 711214
Step 8: Unscrew the 19 mm and 24 mm banjo bolt from the transmission. Both of these are on the side of the transmission. Easiest way to locate them is to follow the transmission oil cooler line like I did. The 24 mm banjo bolt required a little bit more force so make sure to use a rust penetrator before unscrewing them. Make sure to put a drain below them to prevent leakage. There were only 2 drops that came out of mine.
Step 9: When unscrewed, now is time to remove the 8 and 10 mm bolts holding these plastic tabs that hold the cooler lines into place. There are about 2 per line if the others have not been disintegrated from old age.
Step 10: The best way to remove the lines is by sliding them out towards the transmission (rear). Once removed, you can witness the difference between the new and old lines.
Attachment 711215
Attachment 711216
Step 11 (Optional if you want to change the transmission oil cooler itself): Use a 13 mm socket wrench with extension to remove two 13 mm bolts holding the cooler. One is on the LH side of the cooler and the other is in the front of oil cooler. To access the front one you need to go from the front bumper and use an extended socket wrench to take it out.
Step 12: Disconnect the coolant pipes running to the the regulator. You need a small flathead screwdriver to unclip them. I was scared to break these but it's quite simple, just put the screw driver below the clip and push up gently and it should go to a fixed up position and you can unplug the two coolant hoses from the front and back. Warning, the third coolant access area is behind the regulator and it doesn't stay into place with hoses like the other 2 but rather sits on top of an access port with an o-ring, therefore you need to pull the cooler with the regulator towards yourself or the wheel well. Coolant will gush out immediately. Best way to prevent coolant from gushing out like crazy is by putting nitrile gloves into the pipes gently. You will still need to bleed the system eventually. You can remove the whole oil cooler now and work on your work bench or floor.
Step 13: Now you can remove the 3 torx screws holding the regulator into place. They are 30 torx.
Step 14: Pry off the regulator with a medium flathead but be gentle to not break the regulator. If you break the regulator it costs $90-$100 to replace.
Step 15: Take off the old o-rings.
Step 16: If you are changing out the oil cooler too, make sure to NOT use the o-rings that are provided with the oil cooler from packaging. They are too big and will crack the regulator. Do not ask me how I know. Use the OEM o-rings: 17111711987 I had to change out my whole oil cooler since one of the hoses and connectors was so rusted that it was impossible to remove and when I tried pulling it the piping welds broke off from the oil cooler.
Attachment 711218
Step 17: Reverse order everything. Make sure to not forget the third o ring that is for the middle port of the regulator. It goes in between these two bumps to keep it into place. It might feel too small but it is the perfect size once it is put on.
Step 18: Bleed the system using Timm's method: https://www.meeknet.co.uk/e38/E38_Bleeding_The_Cooling_System.htm
Step 19: Enjoy a nice drink and enjoy one less leak on your BMW
Member
Nice job G!
Yep, its pretty straightforward, isn’t it? Thanks for sharing!
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