m52 engine rebuild questions
 

I am trying to figure out what I should do with it.
Long story short, this car I got had a bad valve seat that broke apart and metal contacted the piston, so I put another head on knowing I would probably have to pull out the piston, but since I had the head off already the hook to hold the engine was off.
So put it back together, seemed to run and drive great, but there was this knocking sound from the engine. I quickly decided that I had to get that piston out. So I pulled the subframe, then the oil pan, reattached sub frame, pulled head, removed said piston.
Piston damage prevented one ring from having any movement on one part of the piston, so I am pretty sure thats where the noise was coming from.
I have another piston and con rod for that cyl. I plan to rehone that cyl and put in new rings and rod bearings for it as well.

Should I go ahead and replace all the other piston's rings and rod bearings since I have the head and oil pan off at the same time?
Engine has 122k on it.

Also what is a drei bond 1209 substitute?

That is a good question, and I could argue it either way. This is a pre-'94 so does not have the Nikasil coated cylinder bores, so you won't go too far wrong whichever you choose. Based on this engine's reputation for going 200k+ on original rings and rod bearings, I would probably not touch the undamaged ones, but as I said, either decision has its arguments and I see no real downside.

i just got done rebuilding my whole block on my m52, id do a compression test to see if your leaking compression. i had no choice as i was leaking it baaadd. if you plan on keeping the car for a long time it mite be a good idea to rebuild it.

Found this thread here under my user id. Just thought I would follow up.
I ended up replacing only the 1 bad piston and left the other 5 alone.
Well, car has 140k on it now and is my daily driver now. I get excellent MPG on the highway.