BMW 745Li Transmission Leak Service Rennsport Kansas City

Had this nice ’05 745Li in the shop this week for a fluid leak from the transmission.

After cleaning everything up, I noticed the drain plug was slightly loose, so I tightened that up, drove it and rechecked it. Unfortunately it was still leaking, apparently from the front corner of the pan, so time to pull the pan and repair the leak.

Pan off the car.

The hole on the left closest was the culprit, and while I figure the composite pan is likely cracked there, I didn’t get a chance to inspect it too much.

BMW is using a really slick system on these transmissions. They state the fluid is lifetime fluid and does not need to be changed. In part, that is correct. The fluid is rated for the lifetime of the transmission. That may be 60k miles, 100k miles, or 200k miles when it fails. The transmission has no extra filter, but rather it is integrated into the oil pan itself, as is the pan gasket in this case. Just order one part, plus fluid, and slap everything together. No trying to line up gaskets and keep everything together while you try and wrestle bolts into place, instead, everything is just 1 unit.

With the new pan in and torqued to 10nm, the new fluid goes in, levels are checked at 40 degrees C, and modified if necessary, and then off she goes. No more leaks.