Torque Converter Issues? [Archive] - Bimmerfest - BMW Forums

: Torque Converter Issues?

06-12-2012, 03:53 PM

Having some issues with the transmission thats been dragging on now for 6 months or more, I will quickly run over the history of whats been going on up till now:

Bought the car back in May 2011, gearbox was fantastic, smooth shifts and accelerated great! :D

It had a small gearbox oil pan leak.. <10mm diameter drip under the car each day. no noticeable degradation of performance.

Then in November shifting was gradually feeling notchy and a noticeable decrease in power, although very slight.

Changed transmission fluid and pan/filter in Jan, was going pretty well, much better but still something not quite right, this began to get progressivly worse where the car was sluggish and felt very underpowered. Other symptoms included a delay of 1-2 secs to engage reverse, and when hot not coming out of park.

On the way home from a 40 mile trip, while sat at traffic lights the 'Transmission Failsafe' error showed up on the dash, and a warning on the iDrive that reverse gear may not be selectable. When I tried to park the car it would not go into reverse, and then failed to go into any other gear, even when cooled down.

Pulled the pan and then the mechatronics, found the adaptor seal to have a huge crack on the high pressure oil input from the pump. replaced this and refilled with ZF lifeguard 6.

All was good, shifting silky smooth, fixed all errors and other gear issues but... the transmission seems to slip, i.e. doing 30-40 hammer the pedal down and the revs go up but the car slowly accelerates. its as if the torque converter is not efficiently transmitting the power and/or its not locking up. fuel economy is horrific, its 15 - 17MPG if im lucky and car lags and feels really sluggish when up to a constant speed like it wants to slow down.

Im sure mechanically the gearbox is sound, the clutch packs that I could see with the mechatronics out looked fine and had plenty of meat left on them (98k miles) no debris in the oil or on the magnets (other than the usual fine grey residue).

Whats bothering me is the EGS is not logging any error codes! surely if the EGS commands lockup and its not achieved then an error is stored, unless the lockup is inhibited? Replaced thermostat this weekend due to coolant not exceeding >80 degrees celsius, reset EGS adaptations etc... (TC lockup is affected by coolant/oil temp)

Car seems to respond better when in the manual program.

This car drives fantastic when it works properly, its just disappointing im not enjoying is as much as I should!

Has anyone had any experience with the torque convertor packing up? any help or suggestions will be welcomed!