Greetings everyone. Just test drove a XJS v12 5.3 L 1992. It has been sitting in a car park for about 9 months. Prior to test drive it had a full non-driving inspection from a third party and everything passed; slight oil leak from sump gasket, coolant reservoir will need replacing with aluminium one. No rust on body. New AC.

Only one issue came up from the test drive: when I stopped on a hill and then put my foot on the accelerator it seemed that the first gear clutch plate slipped; the car lurched forward, didn't take off smoothly. As I drove the car for about an hour, didn't really notice it again. Went back to the same hill and repeated process. Much less noticeable second time around.

Would this be an issue with the clutch plate and is it a sign that a total rebuild is needed in the future?

Have no experience with this model transmission; only a 4L80E on my Daimler Double Six.
Many thanks,
Charles

 

Let me follow up by stating that no other gears "slipped" and when I tested reverse, it was totally fine.

Could it be transmission filter?

Charles

 

Sitting so long will be the root cause.

Followed very closely by very stale trans fluid, and the Dacron filter is possible screaming for a change.

The TH400 is TOUGH, but LUVS fresh fluid regularly.

 

Dear Grant,

Thank you! Filter will definitely be replaced and fluid flushed.

Am I correct: this is a GM400 transmission?

Charles

 

Charles.

Yes, GM Turbo Hydramatic 400 3 speed beast.

After the 1st fluid filter change, drive it about a week or so (about 200kms) with as many gear changes as possible.

Then syringe the now old fluid out via dipstick tube. This is simple, find a long hose that will push smoothly down the tube, I use the nylon stuff used for sprinkler systems, attach a suction syringe (usually 500cc capacity) and suck it out, one syringe at a time. It will be about 5ltrs, (not specific), so 10 sucks should do.

Refill as per the specs, I refill the same amount I took out, that trans is NOT fussy on levels as much as the newer stuff, do it again next week etc etc, until the colour sucking out is about the same as the stuff going in, you are done.

I HATE these flush machines,they can sometimes reek havoc with all that new fluid ,and the trans goes legs up, as does your wallet.

The trans is about 15ltrs DRY fill, but unless you dismantle and split the converter you will never see DRY fill specs.

The filter I usually do at about 5 year intervals, and the suck and refill annually AFTER that initial "catch up".

ALL my Jags have had the suck and refill when I first get them. The S Type and the X Type took 8 cycles before I was happy, and now, the changes are undetectable.

Take your time, there is no rush, its a Jag, they be very patient "ladies".