Transfer case oil change procedure

[Barrett1]

I documented it over here.

Post in thread 'Front differential, rear differential, and transfer case fluid levels' https://www.theineosforum.com/threa...er-case-fluid-levels.12420767/post-1333377024

Thank you. That is helpful but doesn't fully answer the questions. You basically say put back what comes out, but what if it was low initially when you removed check bolt? What if it was really high? Would u then just fill to appropriate check bolt level, or only put in what came out?

Sean

 

[Greasemonkey]

My original transfer case was replaced with a different one as part of a recall in the first year at around 5,000 km. Since I had the same questions regarding the oil change procedure in conjunction with the oil cooler, I checked the oil level in the transfer case at around 18,000 km. To my surprise, about 700 ml of oil leaked out of the transmission after opening the check/fill plug, which shouldn't have happened. I then drained all the oil, and another 2 liters came out, which together corresponded to the total fill capacity. Since this amount was pointless, as it would have been impossible to measure the oil level using the overflow method, I pumped the 2.7 liters back into the transfer case. This can be done with a pump. You simply attach a suitable nozzle to the fill opening on the transfer case and pump in 2.6 liters. Then quickly cover the opening with your thumb and close it again.

After driving approximately 13,000 km with an overfilled transfer case, I discussed this issue with my dealer. Suddenly, they were talking about a total oil capacity of over 3 liters. However, no one could provide me with proper instructions on how to change the oil in the transfer case and the cooler. I then calculated how much oil could be in such a cooler and in the lines and arrived at just under 600 ml. Together with the 2.1 liters in the transmission, this brings the total oil capacity to the specified 2.64 liters.
Based on this finding, I decided that the dealer had made a mistake when changing the transfer case and had overfilled the transmission, as they didn't have any reliable data at the time.

I drained the approximately 2.7 liters of oil from the transfer case and refilled it with new oil up to the overflow at the filler opening, which corresponded to the required 2.1 liters. I've now driven approximately 27,000 km and checked the oil level in the transfer case several times. It has remained at the level of the filler plug ever since. I haven't had to top it up.

I haven't yet found a good way to change the oil in the transfer case and the oil cooler. I'll simply change the oil in the transfer case more frequently, which will keep the total amount of fresh oil in the system high. Of course, I could also remove the hoses from the oil cooler, but that usually makes a mess. It's easier to just spend €20 more often for 2 liters of transmission fluid.

 

[Clark Kent]

Thank you. That is helpful but doesn't fully answer the questions. You basically say put back what comes out, but what if it was low initially when you removed check bolt? What if it was really high? Would u then just fill to appropriate check bolt level, or only put in what came out?

Sean

Hey Sean @Barrett1,

The takeaways from my post were:

• The TC capacity is 1.8 litres. The system capacity is 2.64 litres.
• The TC is fill to spill. No more no less.
• If you drain less it might mean it was underserviced previously. Fill to spill (fill the TC until new oil is dribbling out the filler port) will correct that.
• If you drain more it's possible that someone managed to overfill the TC previously but you won't know that. Regardless, you need to ensure the plumbing and cooler circuit are full before you pack away your tools. My approach to do that was to operate the pump (rotate the drivetrain) to prime oil through the cooler circuit then recheck the level until it stabilises at the filler port.

I'm still waiting for a response from IA for a consolidated cooler and TC oil service procedure, including draining the cooler without disconnecting a hose/pipe.

 

[Barrett1]

Hey Sean @Barrett1,

The takeaways from my post were:

• The TC capacity is 1.8 litres. The system capacity is 2.64 litres.
• The TC is fill to spill. No more no less.
• If you drain less it might mean it was underserviced previously. Fill to spill (fill the TC until new oil is dribbling out the filler port) will correct that.
• If you drain more it's possible that someone managed to overfill the TC previously but you won't know that. Regardless, you need to ensure the plumbing and cooler circuit are full before you pack away your tools. My approach to do that was to operate the pump (rotate the drivetrain) to prime oil through the cooler circuit then recheck the level until it stabilises at the filler port.

I'm still waiting for a response from IA for a consolidated cooler and TC oil service procedure, including draining the cooler without disconnecting a hose/pipe.

 

[Barrett1]

Hey Sean @Barrett1,

The takeaways from my post were:

• The TC capacity is 1.8 litres. The system capacity is 2.64 litres.
• The TC is fill to spill. No more no less.
• If you drain less it might mean it was underserviced previously. Fill to spill (fill the TC until new oil is dribbling out the filler port) will correct that.
• If you drain more it's possible that someone managed to overfill the TC previously but you won't know that. Regardless, you need to ensure the plumbing and cooler circuit are full before you pack away your tools. My approach to do that was to operate the pump (rotate the drivetrain) to prime oil through the cooler circuit then recheck the level until it stabilises at the filler port.

I'm still waiting for a response from IA for a consolidated cooler and TC oil service procedure, including draining the cooler without disconnecting a hose/pipe.

That does clarify and distill more, thank you. Also spoke to head service manager at my local dealer who is really good. Fill to spill basically BUT, he did say if oil is really hot, it may be above fill level and you may need to pump a few extra pumps and plug it up. Takeaway, drive and let cool enough that oil flows well but isn't piping hot, drain, then fill to spill.

 

[ItalianAmerican]

So talked to the tech in San Antonio and apparently the max fill on the diffs is supposed to be a couple MM’s below the top of the fill hole. So you aren’t supposed to fill it all the way up or it is over filled.

Why oh why would they not make to overflow like EVERY OTHER VEHICLE!

 

[HereinDaRockies]

Why oh why would they not make to overflow like EVERY OTHER VEHICLE!

Blame the axle maker?

 

[ItalianAmerican]

BMW engine plastics failing is a well known weak point.

As the owner of a 15 year old E90 i can attest this is true!

 

[ItalianAmerican]

Blame the axle maker?

But if the axles are Carrero/John Deere, then they should be fill till the top of the filling hole...

 

[ItalianAmerican]

View: https://m.youtube.com/watch?v=VILo-z5jcEA&pp=0gcJCU8Co7VqN5tD


This should help on the Differentials and other fuild questions. Got it from the post on Transmission fluid change.