HELP - Oil leak

[gsd2000]

To start off with i was driving over some speed bumps and heard a banging from the boot, at first i thought the boot was open as I'd taken my mum shopping. I had a look and i think it was just two cans of holts tyre weld bouncing about.

I decided to have a look underneath and noticed some oil stains on the exhaust and parts of the diff. Jacked the car up and found this













The stains of oil seem to be in a coming from the bolts on the front of the diff. I assume the bit between the diff and the prop is my doughnut.

Is this serious?

Can i complete the dyno day safely without breaking the diff?

What could be the cause of problem?

Seals gone in the diff?

I know some of the photos are not brilliant but it was the best i could do

[gsd2000]

I assume the you are referring to the coupling as the part covered in oil?

There are no oil stains on the drive or anywhere where i have parked up.

I will take the car for a quick drive now and listened out for any knocking. The knocking was more of a banging but only when i went over a large speed bump a bit quick, never noticed it going around corners.

If its not knocking i will quickly check the oil tomorrow morning.

I assume to check the oil all i do is undo the top fill plug?

Should the diff be full up to the fill plug?

If its still leaking and lost a fair bit of oil i will have to pull out from tomorrow's dyno day

[gsd2000]

crap, just read monkfish's reply. Suppose i will have another good look tomorrow, add some loctite and retighten. I have warrenty, just hope they cover the diff, other wise its a second hand one or a 3.91

[gsd2000]

i may have to trailer the car to you then to rebuild i will dig up my warrenty papers and have a good read. I just hope they cover it otherwise it will have been a very expensive year for me

[gsd2000]

there were oil stains above the front of the diff on the under side of the car

[gsd2000]

diff sounds fine apart from when i go over large speed bumps, but with it leaking oil, i don't want to make it worse by sticking the car on a set of rollers. I also don't have any diff oil to top it up with.