Kubota engine failure. Please help

[Agvg]

Didn't read it well enough, acid works nice, have used it on steel cylinders in outboard engines.

 

[manugoss]

Is there damage to the cylinder or just melted aluminum? It its just melted aluminum you can try the trick with acid to remove aluminum.

It was just melted aluminium on the cylinder wall. This morning I cleaned the cylinder. I tried the muriatic trick and it worked better than expected. After all the aluminium was gone, nothing would catch a fingernail. It looks better in real than on the picture below. Just for good measure, I removed the 3 other piston for visual inspection and they all look good. I did the ring gap test and everything is below 0.020''. As for the head, I cleaned all the leftover gasket and the flatness measures with a straigHT edge and a filler gage is well within .001''. I will just stone all 4 cylinders and try to find an oem 76.3 mm piston and ring and reassemble the whole thing.

After the removal of alu in the cylinder:

 

[powerscol]

If you are honing all the cylinders, I suggest new rings on the old cylinders when doing the install. That way the will break in correctly. Rings are cheap insurance. Did you check the bearings? Again if you disconnected the rods from the crank as it looks like you did, just replace the bearings too. Its apart, so spend a few $$ and do the job right. Piece of mind is worth it.

One last thought - are the rod bolts reusable? If they used a crush washer for install torque, you should replace as some are a one time use item.