It appears your valve body is already worn or damaged, so replacing the valve may not solve the problem, and a rebuilt or good used valve body may be necessary. But here is the link to the ZF info on the replacement:

http://www.jagrepair.com/images/Auto...%20ZF5HP24.pdf

There is an aftermarket valve that has o-ring seals and may work better:

ZF 5HP24 TRANSMISSION PRESSURE REGULATOR VALVE KIT TRANSGO 5HP-24-PR FITS BMW A5S440Z JAGUAR AUDI ROVER - The American Powertrain Warehouse

 

I recently replaced my valve body with a reconditioned one and it was not difficult to do. We have them available in the US and I am sure you can find one in the UK. I would still have the trans control module tested to be sure it is still good I am not convinced your trans is the problem because of two trans having the same problem. Remember that the trans control module and the ECM talk to each other making the trans valve body do what it does. Kind of hard to explain the full operation.

 

Another question did you do the hard reset?

 

Yes I did the hard reset after you mentioned it a few posts ago, unfortunately it had no effect. Worth a try though and thanks again.

 

@ Gus and RJ237, in desperation yesterday I made some phone calls for a replacement box AGAIN! I spoke to one guy quite local ( about 45 miles away ) who breaks jags and they have a very good reputation. I was told there are 4 different variations for the box and the only way to be sure was to check the info plate at the top of the unit. I thought they were all the same and interchangeable? He also said it was best to change the torque converter when doing the change. My original one was binned after the second box was fitted as it may have been contaminated according the the garage, so the one that came with the faulty box is being used now.
I have also located a trans control ECU ( choice of multiples ) off an auction site for around £20 to £40, so I will get one and try that also as I believe it fits all models. Will this need to be coded to the car?
Thanks for all the help and advice guys its really reassuring and helpful when talking to the garages.

 

Members have swapped transmissions between XK8's and even XJ8's without issues. I know the parts are not always interchangeable, especially on the early AJ26 cars, so the valve bodies may have differences but I'm not certain.

I bought a used TCM and am able to use it without a refresh, but it's an exact match number set. I have been told by experts that a refresh is often required.

 

Thanks for the update RJ, when I get the car back I will check the TCM numbers and hopefully may be able to get one with the correct spec. I am also thinking about importing an upgraded value set : ZF 5HP24 TRANSMISSION PRESSURE REGULATOR VALVE KIT TRANSGO 5HP-24-PR FITS BMW A5S440Z JAGUAR AUDI ROVER - The American Powertrain Warehouse to cover all bases, but will have to check out shipping and import duties.
First I think the TCM is the priority and the cheapest option, but I will have to check numbers before purchase as you point out. Thanks again for the help.

 

You might want to replace the main pressure valve with the ZF update version, just to see if it helps. There will be several sources in your country, and the cost when I did it was under $30 US. It only takes about a hour after the pan and filter are off.

 

Hi guys, a quick update. Well not really as the shop have not contacted me again so far. However I have seen this thread by a member called Weatherforcast who is located in the U.K, and he has bought the kit. Here is the link
https://www.jaguarforums.com/forum/x...ng-kit-146100/

I was wondering if any other XK or XJ members with the ZF 5 HP24 boxes were interested in a bulk buy for the kit? If they were we could maybe secure a discount?

I will be buying one of the kits soon in order to try and solve this problem once and for all and for the cost of around £80 ( according to the thread ), I'm willing to try it.
Thanks to Weatherforcast for the thread and the information.

 

I bought the upgrade kit today, just the import charges to account for now.
Also I am going to get a replacement TCM from ebay if the shop cannot fix the fault, am I correct it is located in the engine bay under the black plastic cover on the N/S?

 

Well I got the car back on Thursday evening, and as luck would have it, the fault still remains. I was told that 4 new valves had been fitted to the valve body at a cost of £180 and the car was now driving perfectly after an extended test drive. Before I got home I knew the problem was still there and as I drove onto my drive I felt the car bump forward. On Saturday I took it for a run and as I approached lights and stopped I put the car in neutral, when lights changed, into drive and when pulling away there was like a two stage effect. First stage I could feel the drive being taken up then a bump into first gear. If I went from neutral to drive without waiting for the take up it bumps really hard into gear. I will be contacting the shop first thing on Monday morning for a full refund.
The valve repair kit arrived from the U.S on Saturday morning also, don't know what to do with it now though.

 

Spoke to the shop today 0930hrs and they had a few suggestions. 1) Refund. 2) Complete refurb of another box and torque convertor, they will wave the fitting charges, I would need to pay £750 for the job. 3) They suggest that as the problem is the same as original there may be a fault with the wiring harness or the TCU.
At least there are options, but at this point I am unsure of which to choose. Think I will go with the refund and put it off the road until next year as tax runs out at the end of the month anyway.
Any suggestions from you guys?

 

Well another step in the diagnostic chain is to change the TCU, bought one today from Autoreserveparts. Hopefully this may cure the problem....
What an awful job to get access to the TCU, those four special headed bolts with only half a portion showing. Got them out with a broad bladed long screwdriver, the back two were very difficult to remove, perseverance won the day. Now how to actually remove the cantilevered clip from the TCU without damaging the 16 year old wires and fittings, strangely they all look like they were fitted yesterday.

 

I replaced those screws with hex head cap screws. I hope you remembered to disconnect the battery before swapping the TCM's. You need a hard reset anyways.

 

Thanks for the input RJ, I just placed the order for the TCM today, should be here in a day or two, but thanks for the reminder to disconnect the battery and hard reset.