What seal has gone

You do get a bit of smoke from the filler.

Was there any pressure behind it?

Nothing massive to be honest, sucked more than anything. I kind of jumped to the conclusion that it was piston rings because I knew the head was going to have to come off to fix the cause, weather it was bottom end or head related.

Then I saw that the pistons where in pretty bad condition and I though that they where the problem because of that.

So new pistons ordered and fitted, rebuild the engine and turn it over, still with no exhaust manifold on to check for any signs of oil. It was fine on idle until I gave a bit of throttle and it was exactly the same.

So whipped the head back off (no signs of oil on the new pistons) and replaced the stem oil seals. These also looked to be in bad condition. I checked all the valves, cleaned and re lapped them in.

Head back on, started back up and it was exactly the same. I then dropped my only torch into a container with 20ltr of used oil in it and decided to call it a day.

Well you seem to be working through all the possibilities. It'll be pretty much like a new engine by the time you've finished.

Right, a little update.

After not touching my engine for nearly 2 weeks now and after many discussions with army mechanics and land rover 'specialists' at Keith gott, we have come to the conclusion that the only thing it could now be is the valve guides OR something else to do with the head.

I will post back up when I try another head

New head on and it seams to have sorted out the problem