Xk8 automatic gearbox issue
Discussion
The best course of action would be to start by verifying that the gear cable is correctly adjusted. If the gearbox detents do not line up with the J gate detents, and the lights on the J gate don't come on at the exact right time, then the cable and potentially rotary switch must be adjusted.
If the system required adjustment then test and see if the delayed engagement is fixed.
If it isn't then add a half litre of oil through the fill plug which is at the back of the gearbox. If that works, leave well alone.
If that does not work, disconnect the battery to reset the TCM adapts and see how this works.
If engagement is still delayed add another half litre of oil.
If this still does not work then go to a specialist in these transmissions.
If the system required adjustment then test and see if the delayed engagement is fixed.
If it isn't then add a half litre of oil through the fill plug which is at the back of the gearbox. If that works, leave well alone.
If that does not work, disconnect the battery to reset the TCM adapts and see how this works.
If engagement is still delayed add another half litre of oil.
If this still does not work then go to a specialist in these transmissions.
Essential to use the correct oil - Esso/Mobil LT 71141 aka Lifeguard Fluid 5.
Try ebay or buy a kit of filter, gasket, oil and O ring from British Car Parts.
Absolutely essential to work cleanly and prevent any contamination entering gearbox.
Filler/weir plug is 8mm female hex at right rear of gearbox. Difficult access and right by exhaust pipe. Crack off plug and all sump bolts before draining oil.
Drain oil, remove sump and filter. Clean sump and magnets, fit new O ring to filter and fit filter to gearbox. Renew gasket if old one damaged, Copperslip sump bolts and refit sump.
With car level do initial fill of 4-5 lts until oil is level with and runs out of weir hole.
Final fill is done with assistant starting engine and slowly cycling gearbox through D N R. This will draw oil up into the gearbox and sump level will drop. With engine still running and assistant continuing to cycle gears, quickly add more oil - possibly another ltr or two - until oil is again level with weir hole. With engine still running and assistant still cycling gears now replace weir plug.
Correct oil level is indicated with slight trickle/drip from weir hole with transmission cold, gears cycling and engine running. Removing weir plug under any other circumstances will cause flood of oil.
Oil expands as it heats up. You have a just a couple of minutes from cold start to get the level right before the oil starts to warm and need a means of quickly adding oil on the final fill I've adapted an old washing machine extract pump which works fine but whatever method of pumping you use it's essential to avoid cavitation and aeriation of the oil.

Try ebay or buy a kit of filter, gasket, oil and O ring from British Car Parts.
Absolutely essential to work cleanly and prevent any contamination entering gearbox.
Filler/weir plug is 8mm female hex at right rear of gearbox. Difficult access and right by exhaust pipe. Crack off plug and all sump bolts before draining oil.
Drain oil, remove sump and filter. Clean sump and magnets, fit new O ring to filter and fit filter to gearbox. Renew gasket if old one damaged, Copperslip sump bolts and refit sump.
With car level do initial fill of 4-5 lts until oil is level with and runs out of weir hole.
Final fill is done with assistant starting engine and slowly cycling gearbox through D N R. This will draw oil up into the gearbox and sump level will drop. With engine still running and assistant continuing to cycle gears, quickly add more oil - possibly another ltr or two - until oil is again level with weir hole. With engine still running and assistant still cycling gears now replace weir plug.
Correct oil level is indicated with slight trickle/drip from weir hole with transmission cold, gears cycling and engine running. Removing weir plug under any other circumstances will cause flood of oil.
Oil expands as it heats up. You have a just a couple of minutes from cold start to get the level right before the oil starts to warm and need a means of quickly adding oil on the final fill I've adapted an old washing machine extract pump which works fine but whatever method of pumping you use it's essential to avoid cavitation and aeriation of the oil.
Edited by Jaguar steve on Friday 13th December 08:53
NormanD said:
brockovrs said:
Ahh nuts! It's done 81k - is dropping the sump a big job?
At 81K it's well over due for an oil and filter change before the gearbox goes BANGThe valve packs have a habit of cracking on the X100 autoboxes which will cause that issue as it will bleed pressure.
If you have a transmission specialist nearby, they will possibly have some in stock and it's about half a day's work. Cost me £380 to have this done also replacing the loom and a solenoid.
If you have a transmission specialist nearby, they will possibly have some in stock and it's about half a day's work. Cost me £380 to have this done also replacing the loom and a solenoid.
AnimalMkIV said:
The valve packs have a habit of cracking on the X100 autoboxes which will cause that issue as it will bleed pressure.
If you have a transmission specialist nearby, they will possibly have some in stock and it's about half a day's work. Cost me £380 to have this done also replacing the loom and a solenoid.
Where did you get that done? Sounds a reasonable price and I wonder if it might be an issue mine is suffering.If you have a transmission specialist nearby, they will possibly have some in stock and it's about half a day's work. Cost me £380 to have this done also replacing the loom and a solenoid.
andyps said:
Where did you get that done? Sounds a reasonable price and I wonder if it might be an issue mine is suffering.
It needs to be done by someone that can do the job properly as level has to be checked a a priscribed tempretureAs you are in Yorkshire I would suggest
Elite & Performance Jags
Post Code DE21 4BE
Phone 01322-265826
Thanks for the recommendations, I had the oil changed in mine as soon as I got it two years ago but wasn't particularly impressed by the local Jag independent garage so won't be using them again. Preston is easy as I have family living close and have used Preston Jag centre for a couple of jobs and was impressed with them.
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