Jaguar Repair: 85 Jaguar XJ6 transmission leak, automatic transmission fluid, fluid leaks

Question
Hey Howard I hope you're doing well. I was searching the internet and it seems you might have a solution to my problem. I have an 85 XJ6 with a 4.2 liter stock engine (I think its series III?). A few years ago the gearbox gave out so I had to order a rebuilt one from the UK. Eventually that gearbox started giving me problems as the shifting wasn't as smooth, and it usually got stuck in the second or third gear, but eventually shifted to the next one if the RPM was kept constant. I believe the shifting problem might be solved if I replace the gearbox wire as I've heard that the gearbox wire should be replaced with a new one if a new transmission is installed? Coming to the major issue, the gearbox is leaking transmission fluid. I top it off with automatic transmission fluid/steering fluid and it seems that the leak is between where the gearbox is mounted to the engine which would mean its coming from the transmission, right? When the fluid leaks out the car becomes completely free. I mean to say that if you put it in gear and rev the car it won't move at all, but when you top it off with transmission fluid it becomes normal. The car is not in the US so I will have to take parts with me when I travel back home. Do you have any idea what could be the reason for the leak, and what could I do to fix it?

Thanks!

Answer
Hi Aly,

There is a good chance that the leak is the front seal. The transmission is a BorgWarner 66 which is a domestic transmission and most any automatic transmission shop can work on it and get parts for it. Shifting problems can be a lot of things and the kick down cable can contribute to it too.

The transmission needs to be removed to correct the leak anyway so you should have the shop clean the valve body and check the transmission for any ware and adjust the bands.

Fluid should be type "G" according to Jaguar but as far as I was able to determine type "G" in the US is type "F". However, a transmission shop tells me that fluids have changed so you may need to consult the transmission shop for the fluid type now.

Howard