[anom3]

The procedure is pretty well documented on here as well as youtube but I'll mentioned a few things that are not:

a) Expect to drain / fill just over 400 ml. Total capacity is about double that but due to all the stuff inside, you will only get half. Technically you should do the fluid change at least twice if you want to replace most of the fluid. If you are not getting 400 ml out of it adjust your suction tube or your transfer case is missing some fluid.

b) Torque settings, at least for my VIN:

All 6 bolts holding the transfer case carrier to the chassis : 20 nm
2 bolts holding the exhaust hanger : 28 nm
Main big nut + bolt holding the transfer case to the carrier : 68 nm
Fill plug : 60 nm

c) Sometime in the mid 2010s, BMW changed the fluid. I don't really know the details but this is when it went from "TF-0870" to "DTF-1". The few posts on forums that mention this change say its because they went to synthetic with DTF-1. My concern was that since I am doing a half drain / fill, I will essentially have 1/2 of the old type of fluid and 1/2 of the new type of fluid. This does not appear to be a problem. I just did about 50km on the car and it runs just fine.

d) I did this on race ramps. Major pain in the ass, but it is possible on ramps. Lots of posts saying the car needs to be level etc etc for the drain / fill. Its probably better for it to be level but when I pulled the fill plug only a tiny bit came out (I caught all of it) so I do not expect any issues on that front. Only 50km on the new fluid so far but no issues at all.

e) This gotcha probably only applies to my car but maybe others... 2 of the 6 threads that hold the carrier to the chassis in my vehicle had separated from the chassis. Quite possible someone had been in there before me and used an impact to remove or attach the carrier. Not really ideal but having some JB Weld on hand to reattach them to the chassis might be worthwhile. Just a tiny bit will do because all you need is for the thread to stay put while the bolt catches the thread. Once the bolts grab the threads you should be able to to thread them in while keeping some tension on the bolt. Like I said, probably specific to my vehicle but worth mentioning as this is the only real hangup I had through the whole process.

f) Maybe specific to my particular year + model (2012.10 production 335ix), but I had significantly less room around the big nut + bolt than I saw on the many videos online. So much so that there is no way to fit my torque wrench in there. A ratchet would not fit no matter what. Depending on your model, expect things to look a little bit different than what you see on the 3-4 youtube videos that show the fluid swap. I am talking about the nut side which is basically between the transfer case bushing and your transmission. I didn't bother trying to torque this to exactly 68 nm as I know 68 nm is basically fairly tight but don't break your arms tight. I ended up using an angled wrench to access the nut. Something like this https://www.toolsource.com/images/pr...um/112696b.jpg.

g) Next time I do this (2nd change, in a few hundred km) I will probably remove the exhaust hanger off the exhaust pipe so I can get the carrier out completely. Depending on how hard it is to do so, maybe its worth while as the carrier gets blocked by it so you can't remove it completely and kind of sits there obstructing everything.

h) I highly recommend changing the transfer case fluid if you are over 60-80k miles. You will notice a difference as well as prolong the life of your (expensive) transfer case.

Enjoy.

[johnung]

Originally Posted by anom3

The procedure is pretty well documented on here as well as youtube but I'll mentioned a few things that are not:

a) Expect to drain / fill just over 400 ml. Total capacity is about double that but due to all the stuff inside, you will only get half. Technically you should do the fluid change at least twice if you want to replace most of the fluid. If you are not getting 400 ml out of it adjust your suction tube or your transfer case is missing some fluid.

b) Torque settings, at least for my VIN:

All 6 bolts holding the transfer case carrier to the chassis : 20 nm
2 bolts holding the exhaust hanger : 28 nm
Main big nut + bolt holding the transfer case to the carrier : 68 nm
Fill plug : 60 nm

c) Sometime in the mid 2010s, BMW changed the fluid. I don't really know the details but this is when it went from "TF-0870" to "DTF-1". The few posts on forums that mention this change say its because they went to synthetic with DTF-1. My concern was that since I am doing a half drain / fill, I will essentially have 1/2 of the old type of fluid and 1/2 of the new type of fluid. This does not appear to be a problem. I just did about 50km on the car and it runs just fine.

d) I did this on race ramps. Major pain in the ass, but it is possible on ramps. Lots of posts saying the car needs to be level etc etc for the drain / fill. Its probably better for it to be level but when I pulled the fill plug only a tiny bit came out (I caught all of it) so I do not expect any issues on that front. Only 50km on the new fluid so far but no issues at all.

e) This gotcha probably only applies to my car but maybe others... 2 of the 6 threads that hold the carrier to the chassis in my vehicle had separated from the chassis. Quite possible someone had been in there before me and used an impact to remove or attach the carrier. Not really ideal but having some JB Weld on hand to reattach them to the chassis might be worthwhile. Just a tiny bit will do because all you need is for the thread to stay put while the bolt catches the thread. Once the bolts grab the threads you should be able to to thread them in while keeping some tension on the bolt. Like I said, probably specific to my vehicle but worth mentioning as this is the only real hangup I had through the whole process.

f) Maybe specific to my particular year + model (2012.10 production 335ix), but I had significantly less room around the big nut + bolt than I saw on the many videos online. So much so that there is no way to fit my torque wrench in there. A ratchet would not fit no matter what. Depending on your model, expect things to look a little bit different than what you see on the 3-4 youtube videos that show the fluid swap. I am talking about the nut side which is basically between the transfer case bushing and your transmission. I didn't bother trying to torque this to exactly 68 nm as I know 68 nm is basically fairly tight but don't break your arms tight. I ended up using an angled wrench to access the nut. Something like this https://www.toolsource.com/images/pr...um/112696b.jpg.

g) Next time I do this (2nd change, in a few hundred km) I will probably remove the exhaust hanger off the exhaust pipe so I can get the carrier out completely. Depending on how hard it is to do so, maybe its worth while as the carrier gets blocked by it so you can't remove it completely and kind of sits there obstructing everything.

h) I highly recommend changing the transfer case fluid if you are over 60-80k miles. You will notice a difference as well as prolong the life of your (expensive) transfer case.

Enjoy.

I've got an F30 2015 335ix. It sounds like you went through some bigger procedure than I'm aware of.

On my car, the transfer case fluid change is pretty straightforward. There isn't a drain plug so the old fluid needs to be removed by suctioning it out through the filler hole. See photo.

The only real trick is that a thin suction tip must be used. There are a lot of parts in the way inside the TC so the thin tip must be moved all around to remove the most old fluid. It takes some patience. Typically it takes 650ml-700ml of the new 1 liter bottle (see photo) to refill. So that's about how much can be removed by suction with a thin tip.

I would be nervous assuming that the TC is properly filled on car ramps. It's supposed to be filled with the car level on a lift or on 4 jack stands. Same goes for other fluids.

It doesn't hurt to replace TC fluid often since it will make for a higher percentage of newer fluid in the mix. I do mine every 20k-30k miles or so, when it's convenient, just because something else is being done underneath.

Hope this helps!

[anom3]

that's exactly where I drained / filled from. you are right it is fairly straight forward but working under the ramps and the two broken threads made it quite a pita.

as far as working on the ramps... 400ml came out, 400ml went in. I was super careful to catch everything and made sure not to spill anything when suckling out when it came time to use the suction pump. I'll add that i just had a chance to do some spirited driving and zero issues to report... only positives. I'll be doing it again in a week to get more of the old fluid out.

not sure how u can get 6 or 700ml out. my silicone tubes are 6mm and no matter how I tried to position it, after 400 there was no way to get any more.

Originally Posted by johnung

I've got an F30 2015 335ix. It sounds like you went through some bigger procedure than I'm aware of.

On my car, the transfer case fluid change is pretty straightforward. There isn't a drain plug so the old fluid needs to be removed by suctioning it out through the filler hole. See photo.

The only real trick is that a thin suction tip must be used. There are a lot of parts in the way inside the TC so the thin tip must be moved all around to remove the most old fluid. It takes some patience. Typically it takes 650ml-700ml of the new 1 liter bottle (see photo) to refill. So that's about how much can be removed by suction with a thin tip.

I would be nervous assuming that the TC is properly filled on car ramps. It's supposed to be filled with the car level on a lift or on 4 jack stands. Same goes for other fluids.

It doesn't hurt to replace TC fluid often since it will make for a higher percentage of newer fluid in the mix. I do mine every 20k-30k miles or so, when it's convenient, just because something else is being done underneath.

Hope this helps!

[capt_slow]

Is there any value in dumping the entire 1L bottle in there and let the excess drain out? Just to decrease the concentration of old fluid?

[anom3]

I was thinking about doing just that but decided to do two separate fills instead.

Judging by the overflow that was coming out when filling, it needs to circulate to be worthwhile. The overflow was very clear clean fluid.

Originally Posted by capt_slow

Is there any value in dumping the entire 1L bottle in there and let the excess drain out? Just to decrease the concentration of old fluid?