When i bought the '04 XJ8 2 years ago it had 37K miles on the car and was making a transmission whooping noise on downshift. I took it to the dealer and they performed a TSB and TCM re-flash which cured the whoop and jerky gearchanges. The TSB involved draining some of the trans fluid and re-filling with an additive. All has been good until recently, but now the whoop is returning and the gear changes are not as smooth as they once were. The car has 55K miles on it.

The original whooping noise occurred between 4-5-6 gears at highway speeds. The new whoop occurs between 2-3 gear so at lower town speeds.

Any ideas on what to do now? Will a complete trans flush help or could it be more serious he whoop is not as loud as before but it is returning….

Thanks

- Tim

 

I had that problem in my XKR which I no longer own. I was told the additive treatment is a one shot deal. I guess the question is whether the whoop is a condition which is an annoyance only or is it the beginnings of a future catastrophic failure. I have read in this, or another forum it had something to do with the clutch pack. Hopefully somebody here with more technical knowledge can shed some light on this. When I had the problem the dealer first tried the additive and when the sound returned they replaced the transmission, thankfully under warranty. There is a long thread on the xk8 forum discussing this in more detail it being the same trans in both cars.

good luck
brdave

 

Did you ever get this sorted out? I had the same situation and now a few years later it is back.

 

ZF has this to say about that:

If I'm correct the noise you are referring to occurred during the 3-4 / 4-3 shift and was due to the clutch plates humming during apply. Your dealer drained 1 liter of fluid and replaced it with a liter of fluid containing additives to eliminate the noise. This was due to clutch plates humming during apply and was not a wear concern.