I'm doing a manual conversion on a new (to me) '82 300TD with approx. 230k miles. With bad motor mounts, a suspiciously slow starter motor and a leaking rear seal I decided to just pull the engine and tackle everything at once without crawling under the car for hours. I also figured I'd check out the condition of the internals.

So ... with the pan and head off, the block actually appears to be in decent shape. Cylinder bores mic out with .04-.06 piston to bore clearance, with taper of about .02-.03 from the top to middle of the bores - all within the service limit. Cross hatching is visible from about an inch below the top of ring travel. Before taking her apart, compression checked out between 320 (#5) and 340-360 across the rest of the cylinders. Not tip top, but nothing to sneeze at (valves adjusted first, etc., etc.).

So my question for the diesel experts is whether I should go ahead and hone and re-ring her while I have the motor apart? That #5 piston seems to be headed south, though I reckon that even so it has a lot of life left. I've also heard the horror stories of the new rings not seating even with a good hone and the motor ending up eating oil.

That said, my time is valuable and I don't want to tear down this engine again. So what would the experts do? Drop a $130 for relatively cheap preventative maintenance, though with a risk, or let sleeping dogs lie?