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Discussion Starter · #1 ·
Hello all thanks for reading,
Builder replaced the failed B-Drum, valve body, hard parts and the torque converter on a ZF5HP24. So now the car engages into drive and reverse hard and vehicle lurches/lunges when doing so. When coasting to a stop the car bucks as it is downshifts thru the gears. Bucks harder when applying the brakes on your way to the stop light. Up shifting is relatively smooth but not near as smooth as it was before the drum failure. Sometimes, normal driving 30-40 mph, car seems to "hickup" like it cant decide on what gear to use. There is no slipping or a delay in gear engagements. Traveling at highway speeds, say 60-65mph, and i want to pounce the pedal to the floor it will kick down and engage with a very hard bang that shakes the whole car. Also does this when headed up a steep fast canyon. (this is similar to when the B-Drum originally failed and I was at a dead stop and in drive I increased the rpm when it "found/banged" into fourth gear lunging the car forward, skid the tires and the gearbox fault light comes on putting it in limp home mode, felt like someone hit me from behind, really rattles your chain.) I have done this carpet kick down before the rebuild many times and I remember it would do two quick kick down shifts but now it seems like its hoping over a gear and slamming into the next lower gear.
It does any or all of the above scenarios pretty much 90% of the time but sometimes it shifts into drive or reverse normally. After the kickdown bang it wont do that anymore until i shut off the engine. The downshift lurching is there all the time. Dosent matter if the outside temperature is 100 degrees or 25 degrees or when engine is warm or cold.

The transmission fluid runs hot at 225 degrees.
Rebuilder swapped the valve body three times thinking it was a bore issue but with no change.
No codes or warning lights or messages present.
Idle is normal at 650rpm.
Trans fluid cooler in radiator is unobstructed as well as the lines per builder inspection.
Fluid is up to level assuming it was filled with the correct procedure per builder inspection.
Battery is at 12v but it is 4 years old.
No corrosion on pins at Transmission Control Module or Engine Control Module.
Throttle position sensor working tested with live feed code reader per builder.

Is this a torque converter problem that is causing the shifting problems (shifts bad when hot and or cold) and then it is just heating up the fluid to 225 degrees or is it the wrong fluid in there that just wont shift properly at all (shifts bad when hot and or cold) and is just heating up to 225 degrees cause it cant handle the mechanical dynamics of a more sophisticated transmission or is the trans fluid temp sensor faulty (hot or cold) telling the TCM to protect itself because it thinks the fluid is 225 degrees, But wouldent a bad trans temp sensor throw a code? Keep in mind that the car was already hot when the 225 degree reading was "discovered". builder did not put the reader on when the car was cold to watch the temp climb.
Torque converter problem. Could be it has just failed somewhere inside like a sealing ring or something, separated somewhere, or its just a cheap one that cant handle the demands of the ZF. The big question, whats causing this fluid to heat up?
Fluid problem? Before the original rebuild work was started I specified it needs to be ESSO/Mobile LT 71141 or Lifeguard Fluid 5 honey yellow in color. After the original rebuild complete with a "new" rebuilt or remanufactured Sonnax valve body I got the car back assuming it was the ESSO in the trans..... Took it for a drive and all the shifting problems were there right from the start. Took for another drive with the rebuilder sitting shotgun and the live feed code reader hooked up and he got the 225 degree fluid reading and nothing else, no codes, no flags, no lights. We did test the throttle position sensor percentage at 100%. Builder put in another valve body stating it was a problem with the bore(s) causing to much high line pressure. When I got back from a 2 hour lunch and window shopping around the city I noticed the "faulty/new/old" valve body on the table with red fluid all over it. I inquired he said "not to worry the red "spec fluid LT71141" that I used is not the problem it was the valve body." I thought LT71141 was yellow... Car got finished I took for a drive and exhibited the exact same shifting problems described above. Took it back again for the third valve body and a concern of the red "spec fluid" being used. Same story, red spec fluid is fine. So now three valve body's later it is still exhibiting the exact same shifting problems as it did with the second and first valve bodies. And it still has this red fluid it it, I know this because the pan gasket is now leaking slightly.

Thanks again.


2,477 Posts
Hi Jon and welcome to the forum.

I’ve never heard of a failed B-clutch drum on a 5HP24 before. I wouldn’t become fixated on the fluid temperature. The L322 uses an oil-to-water cooler/heater for the transmission fluid so the fluid nominally operates at the same temperature as the engine coolant. 100-110°C is therefore ‘normal’. The transmission repair place obviously uses a generic inventory-reduction fluid which they put in all their transmissions to reduce costs. You run a high risk that the controller adaptions won’t be able to cope with the changed friction characteristics of the fluid and an even higher risk that the torque converter lock-up clutch will be uncontrolled during its continuous slip mode. For what it’s worth, my guess would be that something has gone wrong during the rebuild.


3 Posts
Hello Phil thanks for the reply and thanks for the welcoming, its good to be here. :)

Correction: Yes it was the A-Drum failure, I should proof read a little better... :)

So torque converter you think is ok it is just locking up because of wrong fluid spec? That friction part makes a lot of sense. Should I have the shop put in the ESSO LT 71141? If that fixes the problem, super. Could you suggest some things to think about looking at that it could be internally?



Hello, thanks for the input,

Yes, I inquired about a reset, he said yes. Ill check again to make sure. Maybe do another reset to see if it behaves.



Thanks to both of you I really do appreciate it.


Does anyone recall if there is a manufacturer that makes spec LT 71141 that colors it red?...

3 Posts
Discussion Starter · #5 ·
Hello, Im back.
The builder and I were able to retrieve these codes:
P1797 CAN Transmission Control Module to Engine Control Module Malfunction.
C1155 Wheel speed sensor. (Stability Control Failure and ABS icon illuminated in dash).
C1233 Wheel speed sensor. (Stability Control Failure and ABS icon illuminated in dash).
I think this is a bad bearing getting metal flakes on the WSS. I clean both front when i change the engine oil every 5000 miles and the message dosent appear again until close to the next oil change but the transmission still persists in hard downshifting even after the cleaning. It has been illuminating long before the rebuild and subsequent hard down shifting in 4/2015. Bought in 11/2011
U1260 SCP(+) circuit failure.
U1260 SCP(-) circuit failure.
LTFT +7 (should be +/- 2 or 3?)
STFT +3 (should be +/- 2 or 3?)

Cleared all the codes restarted and hung around for 10 minutes with engine at idle...........
P1797 CAN Transmission Control Module to Engine Control Module Malfunction, again.
Calculated Load Value at Idle: 17.25-23.53
LTFT e+6.25
STFT -1.5
Same hard down shifting situation immediately persisted upon rolling out of the shop.

I read up on the P1797. Its a huge list of things to check and could be anything. If anyone can pinpoint just exactly what that one little fix is in one of these systems that is affecting the shifting that would be fantastic.

Builder assured the correct LT fluid used.
I read somewhere that 122 degrees is a little hot but not to worry about it.

Thanks everyone for your knowledge, expertise, feedback and especially the time you spend reading and answering questions for people on the forum.

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