I have an 88 735i with the m30 engine and 285k miles. The torque converter has a problem locking up. Sometimes you can feel a surging or pulsing when the converter should be locked up. Other times you don't feel anything at all and it doesn't lock up at all. And sometimes it works just fine but only rarely. I drive the car about 60k per year, so it spends a lot of time in the lock up mode.The torque converter was replaced last year after loosing lockup and it worked fine until this problem started earlier this year. The lockup solenoid was just replaces as well as the valve body was gone through and had new seals installed. None of this helped with the lock up problem. The transmission was rebuilt at 150k and has worked fine until this. The voltage going to the tranney is good, my mechanic installed a manual switch to see if the trouble was inside or outside the transmission. The problem is definitely inside the transmission. The lockup is fairly aggressive and with the manuel switch I can engage and disengage the lockup, it probably works correctly about 1 in 10 times. My mechanic doesn't believe the torque converter is to blame since it was replaced last year. Any help would be appreciated.
