Torque Converter Slipping -- SOLVED --

[benfbuilder]

So I've given it some thinking and I've decided to do a full rebuild. I don't see any point in throwing parts at it when I have 159k on the x and the fluid is most likely original (judging by how burnt it is). I would rather spend a few extra bucks and just do the whole thing over and not have to worry about it. Need recommendations on where to get all the parts, and what to upgrade/replace while I have the whole thing torn apart. Thanks!

[Tuesday]

Did you fix it?

[benfbuilder]

Well, hopefully haha. I just finished the trans rebuild last night. Did all the seals, frictions, and valve body rebuild. Need to do the rear main on my motor then I can get the x back up and running.

[X53Jay4.8is]

Originally Posted by benfbuilder

Well, hopefully haha. I just finished the trans rebuild last night. Did all the seals, frictions, and valve body rebuild. Need to do the rear main on my motor then I can get the x back up and running.

Well all right excited to see the outcome of your re-build. Let us know when you have installed and back in the X.

[benfbuilder]

Ok, so finally an update: I've rebuilt the trans (frictions, seals, gaskets, reman tc, and valve body with updated main pressure piston) and it's back in the car and driving. BUT, I still have the same problem with the LUC slipping at anything above ~4k rpm. It has noticeable loss of power to the drive wheels when accelerating hard and an audible murmur. The only other thing I could think it would be is the lubrication valve. Should I try getting the oversized one from sonnax? They claim it will solve TCC pressure issues. Other than this, the trans is shifting as smooth as butter and feels great! Hoping that RRphil could chime in on this.

[RRPhil]

When you did the valve body rebuild did you swap the four ‘black cap’ EDS solenoids around or did they all go back in their original positions?

I would have thought that your 029 transmission had the latest hydraulics with the later (10mm land width) main pressure valve. Did the one you took out have a 9mm wide bottom land?







Phil

[benfbuilder]

Phil, the solenoids did get switched around. I didn't know they had to be replaced in their original positions. But this is the exact same problem I was having before I touched anything on the trans. And the valve body had the older pressure valve with the smaller bottom land. I replaced it with the new one that came with the zf kit.

[jsoto]

nothing helpful in this post to the OP but THANKS PHIL for the amazing contributions !

[RRPhil]

Originally Posted by benfbuilder

Phil, the solenoids did get switched around. I didn't know they had to be replaced in their original positions. But this is the exact same problem I was having before I touched anything on the trans. And the valve body had the older pressure valve with the smaller bottom land. I replaced it with the new one that came with the zf kit.

That’s fine – if you hadn’t already done so I was going to suggest that you swapped them around to see if the problem moved to a different part of the hydraulic circuit. So there’s no way that the EDS 4 solenoid, which controls the torque converter lock-up clutch, is still in its original position?



It’s just that I notice in your initial post you stated that a fault with an EDS solenoid had also been flagged. Is that error code still present? Unfortunately I don’t know how to translate the (hexadecimal?) error codes from your diagnostic kit into ‘P07XX’ format transmission error codes. Can anyone help with this, please?

So nothing looked untoward with the two LUC valves and the solenoid damper in the lower front block when you had it apart?



You didn’t happen to record the transmission serial number off the green plate? If you have it I can check the manufacturing date and see what level of build you have.



Phil

[benfbuilder]

Phil, it is possible that the solenoid is in its original position, but not likely as I did not take any care in marking/organizing where they came out of the valve body.

The valves all looked to be in good condition when it was all opened up, so I cleaned and replaced them back in their original positions with new Springs from the zf kit.

As for the codes, I have no way to read them here at home. The ones I have are from the dealership when I had them check into this problem.

The serial number off the trans is 0362893

Could I use a multimeter to ohm out the solenoids? What would be a normal reading for them? I would rather not drop the pan just yet if I can help it.

Thanks, Ben