Torque Converter Slipping -- SOLVED --

[RRPhil]

Your transmission came off the production line at Saarbrücken on 10th December 2000 so it missed the F-brake piston upgrade (August 2001) and the valve body assembly upgrade (October 2001).

You could check the integrity of the internal wiring loom and the winding resistance of the LUC solenoid by measuring the resistance between pins 11 & 16 at the 16-pin plug on the back of the transmission.







It should measure close to 6.0 Ohms. Clearly this only tells you that the circuit is intact and doesn’t test the performance of the solenoid, for which you’d need a dedicated solenoid or valve body tester, but it’s still worth doing.

You’ve really completed all four ‘stages’ of identifying were the problem might lie i.e. swapped the solenoid, checked the valve block, replaced the shaft seals & replaced the torque converter. Did the two PTFE seals on the input shaft look okay when you had your transmission apart? Presumably you replaced them anyway with the ones from the kit?



Phil

[benfbuilder]

Phil,

I did replace the F brake piston with the new one.

I will test the resistance right now and report back.

As for the input shafts seals, the old ones appeared to be in very good shape, no gouges or marks on them, but I went ahead and replaced them with the new ones in the kit anyways. I also made sure to get plenty of assembly lube on them to hold them and place.

Thanks, Ben

[benfbuilder]

Ok, just measure those pins and got a reading of 6.3 ohms. Do you think it would be worth a shot trying to get a new solenoid and swapping it out?

[RRPhil]

Hmmm, problems with 5HP24 solenoids are very rare (in stark contrast to the 6HP26 where they’re a common issue) so I think it would be a long shot. Worthwhile swapping them around as it costs nothing but tricky to justify buying a new one based on the current evidence I think.

Could you just describe the exact issue again? The torque converter should be ‘open’ (i.e. lock-up clutch off) at low speeds, then the lock-up clutch is partially engaged at ‘medium’ speeds – in its continuous 3% slip mode to isolate torsional vibration - and it then only fully engages at higher speeds (not sure about the E53 but it only locks solid at speeds above 56mph in the Range Rover). I had diagnostics kit for my L322 that allowed me to monitor & record the behaviour of the lock-up clutch which certainly made diagnosing problems much simpler. Just what we need here!





Phil

[benfbuilder]

Phil,

sorry for the late reply, I was waiting on my code reader to be delivered. it's able to read the transmissions codes and data but unfortunately will not record it. Here's what I came up with: Only one code was displayed 3B stall speed monitoring.

Data read In park:

Gearbox Ratio - 1st
Pressure actuator 1 - 739ma
Pressure actuator 2 - 780ma
Pressure actuator 3 - 780ma
Pressure actuator 4 - 156ma (converter lockup clutch)
Pressure actuator 5 - 780ma
Solenoid valve 1 - on
Solenoid valve 2 - off
Solenoid valve 3 - on


The issue I am having is when accelerating and the rpms get above 3k there is a noticeable slippage and loss of power to the wheels coupled with a murmuring/shuddering sound. It's also not confined to one gear, happens in all the gears when accelerating and above 3k rpm. No issues whatsoever when you keep it under 3k when accelerating, the thing shifts smooth and the converter locks up normally. I tried clearing the code and it seemed to fix the issue for about 3/4 of a mile, so it's seeming to me that since this appears to be an intermittent issue that I have an electrical problem rather than a mechanical one.


I checked the camshaft position sensor on the bell housing and came up with 760 ohms. Pelican parts says it should read 600 ohms. Not sure if that could be related, but seems that more resistance might not necessarily be a good thing.


Let me know what you think, or if there's any other way I can get you more data.

Thanks, Ben

[jcp240z]

Did this ever get resolved? Very interesting and informative thread (although not to the OP)

[benfbuilder]

I do apologize in advance for the untimely reply, but I have finally got this issue figured out. The transmission is fine after the rebuild and functions flawlessly and has been for the past 12k miles now. The problem with the noise I was getting is the AC compressor. I live in California and almost constantly have the AC on. Once winter rolled around and I had the AC off for once I noticed the mystery noise had gone away. So turns out the AC compressor is bad and the transmission is flawless. Basically to summarize the whole issue from the start:torque converter lockup clutch went bad and threw codes, I rebuilt the entire transmission and valve body with zf parts, and got the whole thing working again, still had similar noise and power loss issue after rebuild, finally figured out AC compressor is stealing power from the engine and vibrating when engine is over 3k rpms and giving same symptoms as when torque converter is was bad. What a journey this has been, and I couldn't have done it without this forum. I would like to give a huge thanks to everyone for the all the help and wish you all a Happy new Year!!!

[cncmastr]

Originally Posted by benfbuilder

I do apologize in advance for the untimely reply, but I have finally got this issue figured out. The transmission is fine after the rebuild and functions flawlessly and has been for the past 12k miles now. The problem with the noise I was getting is the AC compressor. I live in California and almost constantly have the AC on. Once winter rolled around and I had the AC off for once I noticed the mystery noise had gone away. So turns out the AC compressor is bad and the transmission is flawless. Basically to summarize the whole issue from the start:torque converter lockup clutch went bad and threw codes, I rebuilt the entire transmission and valve body with zf parts, and got the whole thing working again, still had similar noise and power loss issue after rebuild, finally figured out AC compressor is stealing power from the engine and vibrating when engine is over 3k rpms and giving same symptoms as when torque converter is was bad. What a journey this has been, and I couldn't have done it without this forum. I would like to give a huge thanks to everyone for the all the help and wish you all a Happy new Year!!!

Was it difficult to rebuild the transmission? Can anyone do it?


Sent from my iPhone using Tapatalk

[jcp240z]

If you are mechanically inclined, detail oriented, have a clean space and some time you can. There are a number of threads on it, with pictures on make some special tools out of hardware store pipes to remove locking rings, etc.
Expect to be down for a bit, it's not a "weekend" project.