BMW Transmission problems

It is likely that when your BMW was put back together and torqued down following your repairs that something failed. And, since you indicate that the motor and transmission mounts were changed, the most likely suspect is the transmission pan. The reason why has to do with something that we’ll call “lazy parts memory.” To explain, before your technician removed the old engine and transmission mounts your engine and transmission were quite happy in the positions they had come to assume over the years. Since your BMW is now 20 years old, all the pieces associated with the engine and transmission were quite used to the positions they had assumed and when the mounts were replaced the engine and transmission lined up normally, likely in a manner that hadn’t been seen by them for a long, long time. The result is that certain parts, especially those at stress areas, like the transmission pan can develop leaks along their seams. If the leak is large enough the transmission fluid can drain out of the tranny case, leaving nothing for lubrication and cooling. As the gearing was high and dry, so to speak, it likely suffered terminal wear and your transmission is probably fried. You are looking at a transmission replacement that will likely cost you about $3,000.