Anyone know the proper way to do a Transfer Case Fluid change on 4.4i?

[coachelladoug]

I've tried doing searches for transfer case fluid changes, but found no info.

Anyone know the proper way to do a Transfer Case Fluid change on 4.4i?
Is it just drain, refill, done. Or, drain 2nd time, refill 2nd time, and done? or redo 3 times. Seen many videos online, but none for an X5.

[cncmastr]

Sorry, I should have read what you wrote, you asked for TC and not diff.

[TriX5]

Note: for the post face lift e53 you need special snake oil which you can get at the dealer or ECS tuning. Also, once you flush the TC on the x-drive you need to reset the adaptation values in the computer. A search on here will disclose the procedure.

I just got some fluid for the TC and the gear box but haven't done the fluid change yet.

[coachelladoug]

Hi guys,

Thanks for the additional info. Although, I did not find specific info on how-to change the transfer case fluid, I did find that many here recommend doing a reset of the transfer case computer.
Which, can only be done at a BMW dealer or an Indy that would have the proper software.

More info here: http://www.xoutpost.com/bmw-sav-foru...uid-diy-2.html

Any of you have done the TC fluid change without doing a reset? If yes, how many miles ago?

It seems that reseting is highly recommended as the TC will re-learn based on the new fluid viscosity, etc.

Depending on your answers, I guess I won't be DIY my TC Case, and leave that for the dealer. Maybe I can get a discount since I already have the fluid from ECS Tuning.

[SlickGT1]

I am thinking of attempting it this weekend. I'll let you know. I still have access to a GT1, and know the instructions for adaptation reset.

[coachelladoug]

You are more than half way there. I stopped after I read that a BMW computer is needed to reset the TC.

I hope to hear from others who did their transfer case, without any reset, and have been driving for more than 25K miles.

[SlickGT1]

I plan on doing it without the reset. Driving it around. Then doing the reset, and checking the values after some time to compare. I have a feeling this won't change. If you look at the transfer case actuator, the plug on it has two wires. I bet there are other sensors, but I doubt it will make much difference as long as the oil difference wasn't huge.

If you think about it, it is supposed to take less than a quart. If it comes out like sludge, then yea values might change. If it comes out with similar viscosity, I doubt there will be a difference.

I just can't figure out where the damn drain plug is on the X drive transfer case. I have the Bentley manual, and it not only lacks info on the 4.8is, it also doesn't have legitimate instructions on changing it. Almost seems like the drain and fill are the same bolt, and you have to suck the old fluid out.

[JCL]

If there was a sensor measuring the fluid (like the oil pan sensor) then there would likely be more than two wires, which are the wires that power the actuator. If the sensor measured the capacitance of the fluid, as the engine oil sensor does, then not resetting it would only result in an erroneous indication of the hours remaining until the fluid is out of spec. Not critical to operation, and the only effect would be the indication, not the operation of the actuator.

Or, if the reset is in the computer (not the actuator), then the reset could involve the actuator functioning, and the computer monitoring clutch engagement times, and deciding what the engagement point is given the current fluid properties. Then, it would use that reference point to apply the appropriate clutch pressure for the desired front/rear awd bias. In that case, not resetting it could result in incorrect application of the clutches in the transfer case. If it was a small difference, you wouldn't likely feel a difference or notice any wear difference. If it was a larger difference, you would prematurely wear the clutch plates in the transfer case (if it was too loose) or wear out the actuator by overstressing the plastic gear (if it was too tight). You wouldn't know about the result of not resetting it until you experienced such a failure, and even then it wouldn't be conclusive, so it could be attributed to an unlucky coincidence.

It would be like changing a camshaft and not adjusting the valves (on a vehicle where that is required) because of the assumption that "it was fine before, it will be fine in future". Or changing steering components and not getting an alignment, because of the assumption that nothing else changed. Faulty logic IMO. Still feeling lucky?

[SlickGT1]

Yes I am. And I will check with GT1. And my plastic gear already failed, it's currently sitting 180 degrees flipped. Like I said. I'll take pics of the adaptation values before and after reset. We'll see what happens then.

[JCL]

Excellent. Are you going to do a DFMEA for us?