Spontaneous transmission problems
 

Hello there fellow Jag enthusiasts!

I recently bought a Jaguar XJ8 4.0 made in 1999 with around 234000 km on the counter and have driven it for around a month now with a big smile.

Yesterday I changed the motor oil with new 5W30 oil and replaced the oil filter as I usually do when I buy a 'new' car. (Just to be sure, as there was no date known of the last oil change.)
After filling the motor oil again and waiting some time I did a test drive and suddenly the transmission jerked a lot.
As far as I know and understand this is just coincidence, but I included this in the post anyway.

As of today I tried to ride it again. On engine start (cold engine) the transmission seemed to fully working! It shifted properly and there were no problems at all.
After around 3 minutes of normal driving the transmission started to act up again. The typical high RPM, very little movement followed by a jerk into the next gear (which I assume was from second gear to third) happened again. (followed by a "transmission fault" message on the dashboard)

It seems like it skips first gear, slips into second gear until it has enough speed to shift into third gear, from where the transmission seams to be fine again.

I have not had the option to look into ODB2 error codes yet, as I do not own a ODB2 reader yet (will probably purchase one in a couple of days!).

My guess, due to the fact that the jag shifted properly on a cold engine/transmission is that it has to do with pressure / oil in the transmission ? Is this a possibility?

I'm out of ideas and as I do not have the funds to buy a revised transmission at this time.

If I need to provide more information, please ask!
Thank you for thinking along in advance.

Tristan

The default gear for gearbox failure is usually 4th.
Search for 'ZF 5HP24 failed forward drum' or '5HP24 A drum fault'.

Common for BMW and Jaguar cars.

bob

Hi Bob,

Thank you for your fast reply!
I looked through a lot of topics about the "A drum fault" / "failed forward drum", but I assumed this is different because the transmission works perfectly on a cold start?
Could it be that the transmission itself is still intact, but that there is a pressure problem which occurs on warm(er) transmission fluid?

What would you suggest me to repair? Do you think I need to get my whole tranny revised?

It seems so strange to me that the car would shift so perfectly again this morning?


Tristan

You may want to use the procedure in the tech manual and chack the fluid level. You may just be low.