hi there i have a jaguar xjs 5.3 v12 he 1989 this car has been garaged for 4 years when it was brought out of the garage it started first time every thing worked fine BUT now my auto box is playing up first reverse was fine then it only worked with high revs then nothing i was told to check the fluid which i have done and it took 4.5 litres still no reverse does anybody have any idea what else i can try before its needing a complete re-build thanks for your time yours neil
scottishone@btinternet.com
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Are you saying it took 4.5 ltrs just to top it up or 4.5 ltrs to replace the fluid. Have you got all the forward gears. Regards Peter
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hi there it took 4.5 litres to top it up and yes i have all the forward gears and the kick down is even fine just reverse thanks for your help
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Neil
Is this the TH400 autobox? What colour is the fluid? Any oil/pink sludge in the coolant? Any sign of a fluid leak?
Auto boxes don't like sitting; the Dexron fluid doesn't protect against rust very well and if the shuttle valves get even a film on them they will stick in the valve-chest.
Make sure that the control cable isn't seized and check any vacuum hoses going to the box too. If you can get it up and running, it might settle down with a bit of use.
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hi there the fliud is red its dexron111 cant see any leaks no sludge in the coolant just no reverse i think its a G M gearbaox
Neil
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I'm pretty sure this is the GM400 'box.
Do all the forward gears work OK?
Reverse is applied via the direct clutch (also applied in 3rd when in "D") and the rear band (also applied in "1" - LOW lever postion).
So check it goes into 3rd and also check that you can lock it in '1st' via the selector lever and that you feel engine braking.
If they are OK then check the selector cable carefully.
Check you have vacuum at the vacuum modulator.
It could also be the forward clutch not releasing.
Get the transmission good and hot and change out the fluid a few times, drive it around hot for a bit, that may free things up.
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hi there all the forward gears work fine i can even do a burn out in 1 did this to see if there was any clutch slip i will try driving it about to see if this works thanks for your advise cheers mate yours neil
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Yes, drive it about and stop and put it in R as often as possible. Sounds like the forward clutch might be sticking on. Have you checked the cable adjustment?
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Hi
4.5 litres sounds a lot to lose over 4 years, unless there was a visible leak. The level should be checked with engine running in neutral after engaging all other gears in turn. My XJ12 was garaged for about 6 years and the gearbox was initially a bit baulky, but after topping it up and driving it for a few days it came right. Changing the oil is a pain, as the exhausts and the gearbox sump have to come off as there is no drain bolt. An alternative is to have a gearbox specialist flush the fluid. This is done by disconnecting the gearbox oil cooler lines from the radiator and draining the old fluid from one, while picking up fresh fluid with the other.
The other VERY important thing with re-activating a V12 is that all the rubber components around the engine deteriorate. Firstly, the rubber pipes to the fuel injectors; any cracks or splits, replace them immediately or it can go up in flames at a moment's notice. Secondly, the vacuum advance diaphragm in the distributor can crack, which causes engine problems. Thirdly, the radiator and heater hoses can deteriorate; any leaks there and you could end up with a cooked engine. Lastly, take the time to open up the distributor cap and check that the centrifugal advance is not seized, as this is a very common problem. Twist the rotor arm and it should snap back to the normal position. If not, get the mechanism lubricated, as incorrect advance can also cause engine damage and overheating.
Otherwise, enjoy! The XJ-S is a great car and a true classic.
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On second thoughts, if the car has the Marelli ignition system, then the advice about the centrifugal advice doesn't count. If it has the Lucas system, it does. The Marelli system is prone to losing spark to an entire bank, however, and this usually causes a catalyst fire. If you ever experience sudden power loss, stop *immediately* and check for glowing cats on one side.
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