Sorry I just read this. As you say there is a thicker dent on one side of the key that is the one that fits the north side of the hole in the cam. You can see what we did in this picture.One edge is slightly thicker than the other so putting it in the wrong way would be uncommon. Haven't seen it done on a 4e before but the markings are easily seen once you take the cover off.
This is the answer I was waiting for. My partner did the job to fit it back in and he was pretty sure that it was correct because we took pictures before taking it out and we are as careful as we can be when we operate around engines. Yesterday I advanced the timing on diagnostics to 10* and then I disconnected the battery for a little bit to reset the ECU (if it helps). Reconnected it and checked timing without diagnostic mode and it was running between 10 and 15° on idle. It’s a mystery why it doesn’t go back down to 0. I went for a test drive and it was accelerating smoother than before.Yes its only marked on one side. I honestly can't see you putting it in wrong accidentally without using a hammer.
Yes I changed the small O-ring on the end of the distributor arm. It is genuine.You don't need the head off to remove it mate
From memory of celica distributors there's another seal inside them that can leak,
Was it a genuine Toyota O ring you changed on the end of the distributor ?
Understood. I don’t understand why it is still leaking after I already change the O-ring At the end of the home. It is genuine Toyota. That is why I think that the bearing is leaking and needs to be replaced. I already bought one but I need to know if I can replace the bearing easily.This going back to zero thing is still baffling me.
As for the seal it's not a huge job. You can slide the distributor out of the cylinder head without taking the cover off. Unplug the connector, pop the plugleads out of their holes. There's two 12mm bolts holding it in place. Mark where it is sitting before you remove it so as the timing is not upset too much.
Once that's out you just pull the O-ring seal off and slide the new one into it's place. Slotting it back into the camshaft is straightforward so long as you haven't turned the end of it. You can always remove the cam cover to make this a lot easier.
After refitting you'd be best to check and set the timing again to be 100%
I have the small gasket and I have the new bearing. As soon as I get my new distributor cap and rotator I will get it out and change the dust gasket and bearing.There is another gasket inside the distributor Frankie, you should be able to get a kit with bearings and seals. You can for the celicas still.