Steering box oil leak

I checked the oil in the steering box on my Mk I. It was not up to the filler plug so I filled it with oil to just underneath the plug as the manual says should be done. I looked at the car 24 hours later and there was oil on the floor. Checked the oil level in the steering box, and it was down to where it was before I filled it.

Any suggestions about where I should look for the leak?

I would start by feeling if there is oil leaking from the gasket. If that area is dry then move to the steering column input area. If its not there thn the bottom seal has probably worn out.

clean the area spotless with degreaser, soap & water, wipe it down with rags till no oil shows on the rag. Light the area strongly, and observe the box after a few minutes of moving steering wheel.

for best results, sprinkle talc or cornflower on the box, and the oil will make a visible trace
Just like a fingerprint detective

Years ago I rebuilt a Mark 1 box for somebody.
It is made by Burman Douglas, similar in construction to and takes the same lower shaft seal as for XK120, so you should be able to get one from XK sources.
This job is best done on a workbench, not in the car.
There are postings about rebuilding these on the XK forum.

Thanks for the helpful replies.

Looking slightly closer, it is clear that one source of the oil leak is the seal for the (U-joint) shaft from the steering wheel.

Hi,

the steering boxes leak from the two possibilities to do that, i.e. the entrance from the steering column, where there is an oil seal and down at the main shaft exiting the gearbox, where there is an oil seal, too.
Renewal is not a big affair, and good possibility to check all the ingrediences for wear.
Many parts are available, so even a rebuild is easy to be done

Best regards
Lindi

So its most likely to be either o-rings item 12 or item 18 or both, and less likely the gaskets 10, 13 or 24.

Thanks. Is it hard to remove the box from the car? Do I have to remove the steering column?

Thanks. Can I replace the O-ring item 12 with the steering box remaining in the car?
And can I remove the U-joint without messing with the steering column?

looking at the FSM = not too much messing for the u-joint, and by appearance, yes on the o-ring
(as the top plate can be unbolted, and o-ring slid over protruding (splined) shaft)

new gaskets could easily be handmade, if NLA

the steering column setup appears the same as 420G, I rebuilt my entire column, was not as intimidating as it seems, steering box next.

FSM (or excerpt) is a MUST

take it out, just loose the column, then loose the pitman arm, further 4 screws and the part is out.
All needed items are available.

Best regards
Lindi