XJ-S gearbox problem

[hairykrishna]

I've just bought a '89 XJS V12. All was fine initially (for about 20 miles) but now it seems to have developed a gearbox issue. The only gear it selects is 1st; it occasionally seems to be jumping into neutral.

It has been sat for about a year. Any ideas?

[varsas]

Sorry, not really.

I can only suggest a gearbox oil change as first port of call.

[RW774]

The kickdown cable maybe stuck in the fully open position ( that is throttle valve fully open ).The fluid may well have leaked out also.If this is fine
it could do with a pressure check to see if pressure is lost via top/ reverse drum/servo assembly. If it is down on pressure it will need an overhaul.
Email if I can help.

[hairykrishna]

Thanks for the suggestions. I'll let you know how I get on!

[hairykrishna]

The gearbox oil seems very black. Is it worth trying an oil drain and refill or is it time to start shopping for a new box?

Does anyone have a link to a XJS workshop manual? I don't even know where to start draining the fluid.

[RW774]

Thats fuked mate.If it is black ,its burnt.

[hairykrishna]

RW774 said:

Thats fuked mate.If it is black ,its burnt.

That's what I suspected. So, gearbox swap on an XJS - difficult job is it? I've ordered the Haynes book-o'-lies but any pointers to proper workshop manuals would be gratefully received. Are they any cheap XJS manual gearbox conversions? All the ones I've seen are 3 grand+

[a8hex]

hairykrishna said:

I've ordered the Haynes book-o'-lies but any pointers to proper workshop manuals would be gratefully received.

You can order the service manuals from the owners clubs. You can also pick up copies on eBay I suspect.

On the subject of Haynes manuals. They've just brought out the NASA Apollo 11 Manual

Just what every bloke should own.

[RW774]

It`s a very big job for you to undertake, if you have limited mechanical knowledge. However, have a go! but make sure you have some help at hand and don`t break the exhaust studs !

[hairykrishna]

I just moved it and the gearbox seems to work OK when it's cold. I think I might try a fluid change before going for the full on box swap. I've got the fluid anyway so I'm guessing it's worth a try. Is there any easier way to drain the fluid than dropping the sump?

[RW774]

Unscrew the dip stick tube, be sure to have plenty of containers, don`t touch the sump.

[hairykrishna]

The dipstick tube seems to go into some kind of rubber washer on top of the pan and it's not obvious how it's connected. Is the end of the tube threaded and I can just grip the whole tube and turn it?

[RW774]

Sorry man, I gave the wrong info, slapped wrists an all. You do need to drop the sump on a GM400. Its the 6 which you remove the tube, apologies. Best grab a gasket first, then replace it as it will probably disintegrate on removal.Might as well change the filter too.

[hairykrishna]

Thanks - glad it wasn't just me being stupid! I'll give it a try over the weekend.

[hairykrishna]

I've actually managed to extract the fluid via a siphon tube down the dipstick hole. I've bunged in some fresh fluid and I'm going to drive it to my dads where I can get it up on some proper ramps, drop the sump, and get a better look at the situation.

[hairykrishna]

Bugger. I made it worse.

As soon as the box warms up I lose all the gears. Works fine when it's cold.

[RW774]

Are you checking it again when it has run for a while ? . Check it again with the vehicle running, after selecting all gears.