what could have caused this?

[old man roger]

Originally Posted by adichino

thanks for the checklist dude, i do however like to fix my own stuff even though its my first time when dealing with an engine - worst case scenario i cannot fix it and buy a new one and lose a couple of euros, fuck that

i replaced the crankshaft because it was damaged where the rod which snapped is attached - dunno how its called

i didnt replace the bearings as they all looked the same and good to me

i am using a new set of pistons with a new set of rods - i didnt check the cylinders, just cleaned them and installed the pistons - they were sliding smooth when the rods were not attached to the shaft

so you are saying - judging by your answer - after the rods are installed and tightened the pistons should move when rotating the crankshaft?

quote from wikipedia

OH BOY!!!! I'm going to keep this short because I'm not about to type out every thing you need to know to rebuild an engine.

The bearings need to match the size of the crank and rods, there is a certain amount of clearance required because the crank, rods, and the bearings expand when they get hot.

There also needs to be a certain amount of piston to cylinder wall clearance because the pistons expand when they get hot.

If you haven't checked these clearances then you have not correctly installed the parts.