Hi all, I found a new problem with my 97 XK8 yesterday which I would appreciate some thoughts on; when pulling away from standing the engine revved but the the gearbox did not engage. This happened 3-4 times towards the end of a 2hr drive, I tried changing re-selecting D but this did not seem to work instead the gearbox seemed to re-engage after a few seconds of revving. Other than this the gearbox seems to change well. I ran the IDS software this morning but found no error codes.

 

I forgot to add I had the oil changed last spring at 81k, and its now on 85k

 

I assume you have the ZF5HP24 gearbox, and no drive into 1st is a classic sign of A Drum failure. However in your case, you did a drain and fill only 4000miles ago.

And in your case, your problem only happens when car is hot. I would guess you have bad Spec ATF and/or under or overfilled it.

Does it happen when car is level or on an incline?

Overfilling is just as bad as under. If overfilled, the ATF foams and heats up, leading to gear slippage.

 

To best of my knowledge it is the ZF5HP24 gearbox. It has happened on both a steep hill start and a level car park. I have had no issues since the oil was changed (carried out by my local Jag indy, who I seem to recall checked the level more than once). As I live in a hilly area with very few 'highways' the car has probably done a lot of gear changes in those 4000 miles, so my gut feeling is any issue from the oil change would of arose sooner?

 

Bonsoir,
Yes, you do have the 5HP24.

I would check with your indy that he did use a trans fluid that meets the LT71141 spec, and that the filter was also replaced.

It could be the beginning of 'A' drum failure, but do the easy stuff first:- does drive engage with a thump? Is the fluid level correct?

 

Well, there’s a possibility you have bad ATF. Takes a while until you notice problems as different brands have different properties.

+1 on checking with the mechanic what ATF he used. Zero dollar check.

If the ATF is overfilled, it’ll heat up and gradually, over time, lose its lubricating properties. So the 4000mile is actually a good sign!

See what the mechanic says when he did the drain and refill. Hope he put a new filter in too.

Worst case scenario is that the A Drum is bust and that’s a professional tranny rebuild job! Not many home DIY shade tree mechanics can do it, but it has been done by some expert Forum members here. Also there’s an upgraded A Drum available.

 

Yes the filter was replaced too, I will call him tomorrow to see what oil he uses.
I tested the car again yesterday and it seems to be doing the same on about 50% of standing starts. So I'm not confident driving it now, which has upset Mrs laguillotine's holiday plans!

Thanks