Bore honing

[Jim Phillip]

Have a 240D that was getting hard to start and figured it was likely a leaking head gasket. Surprisingly, pulled the head and it looked excellent, no leakage or hot gas marks. I pulled the pistons though and the top ring on each was broken. Piston walls are totally slick and no crosshatch. Not much cylinder ridge at the top and the pistons pushed out easily. I assume I need to inspect the bore and hone it. The ball hones look easier to use? Pistons are 90mm so I assume the same for the hone? I have also seen 240 and 320 grit hones? Any difference? Will it need to be hand finished with 440 grit?

 

[Gary Reif]

If it were mine I would probably hone it with a 320 grit stone type hone since you say it has minimal ring ridge. It's been a few years since my cylinder boring and honing days but I think we finished honing with 320 to put a nice finish and crosshatch in the cylinders. Just my thoughts.