www.jec.org.uk

ok so just had a complete gearbox drain and refill, new seal, filter, oil change, in my 2001 XJR.
On a very hot day at 90.degrees plus sat on M6 traffic jam crawling for miles, about an hour.. then once off the motorway, in normal town traffic my wife noticed smoke coming out from underneath.. I did at the same time sense the gearbox was lagging to change up.. I then carried on but on the way a warning came up “gearbox too hot” and pulled in after a couple of miles into a service station.
I opened the bonnet , to cool her down, looked underneath and drips of ATF on the ground plus it had gone onto the exhaust and cat so that was burning off.
As I was with Footman James RAC I called him and after checking the bolts found one that he could tighten up a bit more by hand. Then topped up with a litre bottle of Halfords ATF (it said was suitable for that model) I don’t have the dipstick so we couldn’t tell how much was required…
After that and a couple more 2 hour journeys she looks dry under there and appears smooth in take up.

I am a bit curious if such a small amount of turn on one bolt could seep that much oil out .
But on an extreme hot condition, is there a safety valve or pressure vent that allows oil to escape?
Or maybe it was so hot, it forced through a slight weep in the seal that just wasn’t tight enough?
Interested to hear if anyone else has had this experience?

Commonest source of leak is the electrical connector, mine leaked after gearbox oil replacement. I would be tempted to just keep an eye on it, certainly a loose bolt could be the cause of a leak. I notice you also have a XR4, I owned one many years ago, loved that car, probably long gone now….

Thanks Andy
Yeah my Sierra XR4x4 has been great, had to have another one as I regretted selling my original in 2007..

How did you rectify the leak, does the connector have a rubber seal that could perish and need replacement?

Hi, does anyone know if there is a seal or something for the electrical connector? If there is, probably to replace it? Thanks

I am pretty sure you can buy the connector seal as a separate part, or it may come as part of a cable link from the gearbox to transmission ECU. I am sue someone on here will know.

Ah thanks Andy, is that how you cured it?

Hi Stu,

Yes, the connector switch cured the leak, but as I did not do it myself I am unsure of the exact part, sorry.