Torque converter clutch stuck.
 

I've been noticing a clunk when engaging drive or reverse. This clunk is usually preceded by a slight pause then clunk. I did a scan with VCDS and it is showing the torque converter clutch is stuck in the off position. It started doing this a couple of months ago so I had the fluid changed and cleared the codes but it made no real difference. The clunk is still there and the same fault code has come back. Is there a way of unsticking the clutch without the need for a transmission stripdown? If I go to any specialist in Dubai as sure as God made little apples they will recommend a complete rebuild.

Thanks

Steve

By the way, I am assuming that this clunk is due to the converter clutch being stuck. If they are two separate problems, what are they?

The torque converter is a welded assembly and the lock-up clutch is captive inside this welded assembly.

http://i260.photobucket.com/albums/i...LUCsection.jpg
LUC piston shown in green, friction plate in red

http://i260.photobucket.com/albums/i...ullLUCassy.jpg
Piston

http://i260.photobucket.com/albums/i...lateinsitu.jpg
Friction plate

The torque converter can be replaced without opening up the transmission but the transmission assembly has to be removed from the vehicle to provide access. The torque converter simply slides off its splines and no specialist transmission knowledge is required to replace it – any competent mechanic should be able to manage it. The only tricky bit is ensuring that the oil pump drive dogs are engaged when it is replaced.

The lock-up clutch is fully engaged in the higher gears only to reduce the slip across the torque converter (to save fuel). It is not engaged in 1st or Reverse so I can’t see why it would contribute to a clunk on gear selection.

The LUC is either fully on (locked solid), off (disengaged) or in its ‘continuous slip’ mode (approximately 3% slip) which is used to eliminate torsional vibration at lower engine speeds as ZF decided not to fit a damper to the Sachs W260/280S-2GWK unit to save weight/space.

Phil

Huge thanks Phil from me for all your sharing of knowledge and input to our forum, I'm sure I will try to make many of your replies stickies where appropriate +++ Cheers Neil

Thanks Phil. Very useful information. So, it's not the LUC causing the clunk. Any ideas what it could be?