Another six hours in the shed today and the car is almost back in one piece, just the bumper, cross member and fluids to sort out.
The pulley came off a treat, turns out that there are 3 notches in the back of the hub that your puller can engage in see picture.
Then it was just a case of popping the single remaining bolt out and bingo, the sump fell off. Pictures of the sump too.
You can see from the old and new sensors how much the O ring has crushed, causing the oil leak. the plastic on the outside was cracked too.
On re-assembly, I wrapped the sensor plug and socket in fire proof fiberglass cloth and wrapped the exhaust too. I think that heat from the exhaust is causing the failure. It doesn't look pretty, but it should do the job.
So, to wrap this post up, YES, you can do this job without removing the engine. It will have taken me about 8 hours, with a 4 post lift and knowing exactly what you are doing, this could be cut to 6 hours, but I doubt anyone could do it quicker. I have a pit in my garage and needed it. If you are going to attempt this on a drive or garage floor, you should expect to take in excess of 20 hours!! The cost incurred was £228 for the sender, £10 for special silicone sealer, £30 for a gallon of engine oil, £10 for a liter of power steering fluid and £10 for a gallon of anti freeze.
You will need a comprehensive tool kit, including Torx sockets and a small 3 leg puller. A jack, axle stands and if your exhaust is stubborn, a grinder, drill and welder.
I now know exactly how to do the job and hopefully tomorrow will have one of the few 3.2 Q4 Breras in the country with a functioning oil temperature gauge.
If you want yours doing, please do not call me, you are on your own.