1930 Lister D Restoration

I have another post for my other engine so thought I would create a new post for this one as they both have different challenges!
I really want to restore the other engine first but was curious to see the state of the piston in this engine as it is seized.
This machine had a stud that was broken off in the water tank and consequently, as it was rusted solid, I was unable to lift off the head.
I therefore bought a cobalt titanium drill bit and proceeded to drill through. However, the drill bit wasn't long enough so I decided to sacrifice another bit and to braze it to the first one (never tried brazing before). I used Mapp gas but my torch isn't really powerful enough although after several attempts, I managed to get enough bronze onto both bits and to fuse them together which allowed me to drill all the way through. I was lucky enough to have the head off the other engine so I could gauge exactly how far to drill.
Once I completed drilling, I still couldn't budge the head so I used a wedge that I created using my angle grinder and a steel strap that I tapped into the four corners of the head. This broke the seal and gave me enough gap to insert wooden wedges (bits of old fence panel!). Once I had wedges under all four corners, I was then able to lift off the head. Luckily no damage to the head but I will need a new copper gasket!
All looks good but I now have to figure out how to free up the piston!

P.S In the photo showing the hopper, the stud I drilled is the one at the bottom. Please also excuse my poor brazing!!

Nice, I've never seen drill bits brazed together! You must have done a good job as they're still attached.

I think the best bet to get the piston out would be to put some diesel in the bore and let it sit for a week. Then try to push it out. Some vibration might help if you have an air chisel or something similar?

I assume there's no cylinder liner fitted? It's hard to tell from the photos, if there is it might be possible to press out the liner and piston together and replace both?

Thanks Woodman.
It took me a few goes to get enough bronze onto both bits. After a few aborted attempts, I realised that I needed to fuse the top, turn it over and then fuse the bottom. Few taps with the hammer to straighten it up a little and of I went. Wouldn't win any prizes for looks but it did work.

Unfortunately I'm very basic on tools so no air chisel available. Would it be obvious by looking closely if I had a cylinder liner? If so, (bearing in mind my limited tool collection) what method could I use to press it out?

Craig,
There is no liner, it would be a rebore and oversize piston.

When I extend drills I drill a hole in the end of the drill, turn a spigot on the extension piece so that its a tight fit then chamfer the two ends and weld in the groove and remove any excess.

Maryalice

Thanks Maryalice