mg tf 160 bad head gasket

Hi Max...your second post gives us so much more information!
Firstly your location and that you have a rust free car. That makes a huge difference and means it's worth doing the engine right.
Secondly your skill level has been elevated due to the work you have already done!

I would take the engine out and strip out the pistons, replace the broken piston and re ring them all. Take out the big end shells and inspect the crankshaft journals. They don't have to be "perfect"..there maybe very fine lines..as long as it's not grooved. The bearing shells will give you a good indication.
If the car is good it makes sense to do it right first time. It keeps the car original and you know you will have a good engine you will look after.
I'm good at building engines, gearboxes etc but I know nothing about these engines specifically..but guess what..there are guys here that do! They can answer very specific questions and will get you thru it.
Good luck!

Welcome to the Tbar.

Something else to consider is where did the pieces of piston material go to? 🤔What additional damage, if any, has been caused?

I'm not sure what the shipping would be to SA but good used 160 pistons are available with matching cylinder liner for sensible money  https://www.mgfntfbitz.co.uk/shop/160-vvc-piston-k-series-engine/

Finally got around to removing the piston and can properly see the the damage, was actually pretty straight forward  . Struggling a bit to get the liners out so I'm soaking them in penetrating fluid. 
It's got the number "135" stamped in the side. Could this be a piston from a 135 engine?(or are they the same and it doesn't matter?

 

 

 

I'm wondering where the bits of broken piston ring have gone ,the missing bit of piston are soft so they might not do much damage before they get blown out through the exhaust  if they were small pieces, but piston rings are hard, and I'd expect to see some damage to the top of the piston and the cylinder head if chunks of piston ring were bouncing about in there.
I wonder if some ham fisted ape hasn't broken the piston installing it,  and pulled the lose bit out before bolting down the head and hoping for the best.
What does the bore of the liner look like? 

The big end shell is worn but in a normal way..the crank is probably good but check!
Short pistons..no wonder they like to rev.
I wonder if someone broke a ring whilst replacing them at some time.
Personally I would have left the liners in place unless scoured.

You are far enough on to do a great job of rebuilding it now and the satisfaction you will get is enormous. Well done.

that is quite worrying and I would like to figure out exactly what exactly caused the chip. my one theory is that the liner expanded at that section and the piston started making contact and eventually chipped. But yea, Whoever put this together previously was a bit of an ape and made a lot of little mistakes like using silicone glue to assemble the head and stripping a few threads so not completely unlikely that they broke it. The liner bore looks completely fine at least (will get a picture when I'm tinkering again). I got the suggestion of welding the missing material back on the piston and sanding it to the correct shape. Is this a viable solution?

Thanks!!! haven't removed the liners yet but I did rotate the crank to get access to the piston bolts as I was planning to remove them to clean the water channels a little (They seem to be a little seized and I think the previous owner used some head gasket sealant which is gluing them a little).

Do not even remotely try to weld up that piston!
I will leeave it at that.😉

wrote:

Do not even remotely try to weld up that piston!
I will leeave it at that.😉
 

I agree totally, DON'T attempt to weld up the piston!

Top marks for wanting to have a go but id add my voice to the others, best replace rather than try to repair that piston. Piston repair should only be attempted within a very advanced engineering workshop where they can check and replicate the exact metallurgy and join seamlessly to avoid creating a stress point. It's really only ever worth it if the type of piston is otherwise entirely unavailable.

No, that's a bad idea! I've seen videos of poorly equipped workshops doing remarkable work, that though is a matter of "needs must if the devil drives". I'm of the opinion, as with the rest of the lads, that your missing piece was missing before the head was put back on. If it had broken whilst running (Why/how) it would have left evidence of its departure. Order spares & rebuild.
M