[alex sol]

Gents,
I've removed the transmission to replace the rear main seal.

History on this car is that it's leaked oil from the day i bought it with about 90,000 miles and now with 130,000 miles, it's leaking a ton... a liter every 500 miles

Some of the work i've done:

1. oil filter housing gasket
2. valve cover gaskets x 3 times
3. vanos solenoids
4. crank case vent, bypassed then realized it doesn't open without vacuum
5. front main seal - used the amazon tool where you screw in 10 or 12 screws then pull it out - this required removing the fan which i've done too many times
6. other jobs include: reservoir replace, coolant lines replaced (bleeding the cooling system was quite the new experience), busted the thermostat inside the reservoir and replaced, replaced coolant level sensor (not compatible with the oem reservoir) had to match up URO parts i think
7. pulley replaced, new fan/accessory belt
8. intake off to replace starter
9. installed tow bar, removed rear bumper and push bar (or whatever it's called) and wired up the 4 wire harness for the trailer lights

so some notes for anyone wishing a step by step on how to (how not to) do the transmission swap

[alex sol]

this is an automatic GA6L45E from doing some research.. GM trans also found in 2010 ish Cadillacs and Chevs

1. lift car on 4 x 6 ton jack stands on the driveway, tested for stability
2. pryed off hanger for exhaust - all the weight now on the hanger off the transfer case
3. went to remove the exhaust bolts 10mm complete rust welded on... cut off the exhaust about 12" rearward instead with a grinder and sawzall
4. heat shield 10mm x 6 or more
5. drive shaft now exposed and removed 4 x Etorx 12 (External Torx you find all over these bmw)
6. guibo flex disc - removed 3 x 18mm (note the location though likely replacing with new)
7. removed center bearing 2 x 13mm
8. here's a goofy bit, I yanked on the guibo end of the drive shaft and separated the drive shaft... possible it needs to be balanced now... will take to drive shaft shop and pay $$ to balance or could have save the trouble if i had marked the drive shaft spline location
9. Support trans with wood block and bike jack
10.removed 18mm damper bushing bolt
11. removed transmission mount with 13mm x 4
12. removed transfer case - disconnect harness by press and pull plus a tiny sensor held on by etorx6 mini sized bolt, removed more than the six bolts necessary by accident. only remove 4 x ETorx12 facing rearward and 2 x Etorx12 facing forward. Off comes the transfer case with a wiggle - a good time to check if the plastic wheel inside the transfer case actuator motor is shredded or not
13. drain the fluid from the transmission - i didn't do this, my drain plug kinda rust welded on
14. remove trans cooler lines 1 x 13mm
15. unplug transmission harness
16. unplug to o2 sensors
17. remove six torque converter bolts 19mm, used a medium sized phillips screwdrive and levered off the rectangular inspection hole (usually covered by black rectangular rubber cover) and was enough to spin the engine 1/6 of turn x 6 times while using the extended 19mm deep impact socket
18. remove 10 bolts 3 different sized Etorx. E18 for the large, E14 for the mediums, E10 for the smalls and might have been a E12 but don't recall now
19. pulled the transmission from the engine... got stuck a little, raised the jack a little and got unstuck... the Torque converter started to leak a ton of oil so be ready to catch the fluid... it's mostly on my driveway now...
20. transmission out and by inspection looks like rear main seal ready to swap and some oil still leaking from above (or it's old leak) which is the valve cover

ordering some parts from rockauto though they are not that clear... i ordered the transmission output shaft seal by looking up the 2013 Cadillac ATS and the input seal is called the 'fluid' seal... will double check the part numbers...

[alex sol]

order list:

1. rear main seal for engine and a dab of silicone for where the case and oil pan meet... there is a serious Curil T injection needle for this job and I just use my forefinger and dab on some gasket maker - permatex black or something like that..
2. transmission pan seal
3. transmission filter
4. input and output seals on the transmission
5. guibo flex disc
6. flywheel bolts 19mm x 6... not heavily torqued on... single use I'm guessing

forgot to mention the transfer case has it's own drive shaft / prop shaft... it's held on by 4 x E12 on each side... and same size as the 4 x E12 that hold the main drive shaft to the rear diff... all single use aluminum bolts I suspect...

[richardodn]

That is not a fun job. The last time I had to pull a transmission was on a '99 Audi A4 Quattro. That was enough for me to swear off trans swaps (and Audis). I hope reassembly goes smoothly.

[alex sol]

- trans back in the car after rear main seal and transmission / transfer case seals
- replaced fresh fluids in TC and Trans... 4x4, dsc, ! in trangle warning lights all turned off,
- front drive shaft, main drive shaft back in (regret i did not mark the drive shaft and did split it when yanking it off the diff), kept the old guibo disc - appeared to be in good condition and possible it's not original (previous owner quite diligent with service),
- heat shields,
- replaced exhaust (my nuts/bolts were so corroded it cut it off about 15 inch from the oem connection), purchased 4" long x 2" diameter 'collars' for exhaust and closed off 99% of the gap
- buttoned everything up and had smooth start up appears to have fixed the oil leak (rear main seal area) though still major oil leak on the valve cover area - hits the exhaust and fills the cabin with smoke

in general like @richardodn notes, not a fun job and doing on a driveway on a slight incline, i lifted the trans several times to match to the engine. some major mistakes and redos... get the x3 lined up so the front a little higher than the rear, using a motorcycle jack and had to get the right number of 2x4s and 1x4s so that the TC would stay in the trans and lined up to the two 'teeth' inside the trans.

First crack I joined the trans with the four large bolts and two starter bolts. tricky to have all the different extensions and the goofy E-torx (e18 and e14 sizes) sockets... then only realized i had the flywheel plate on backwards... had to remove and redo when the Torque converter bolts could not reach the flywheel...

Second try, got it lined up properly and figured a way to use a large screwdriver to spin the torque converter by leveraging against the transmission inspection hole (rectangular rubber removed) so there's a few scratch marks on the Torque Converter.

Reconnected the transmission cooler lines (replaced new o-rings).

Trans fluid top up not 100% perfect. Filled with x3 off, then started and topped up until fluids leak back out. Did not switch up all the gears though so possible could have put more in.

Reconnected the shifter is quite odd.. works by a needle shaped rod that is snugged up by small m6 bolt...

Running good now and it was complete about 7 days after starting the job.

[alex sol]

An interesting follow up note: after the work was done, i swapped in snow tires and really messed up the transmission. Felt like something was broken or had disconnected. So I went back under to check for something loose or busted. Turns out the snow tires were quite different front to rear. Rears were much larger and caused the trans to feel either broken or go into limp mode. Couldn't go over 40 mph. Replaced the four snows to equal sizes and running smooth again...