Not recommended-- especially as a pm item. You are asking for trouble. Chances are, if you need bearings, or have high miles, the crankshaft has to be polished or machined to make it last, or get it back to spec, not to mention correcting the original problem that caused any bearing failure, oil pump, sludge, etc. You can just install new bearings, engine in car, and run some emery cloth or sandpaper over the journals to clean them up, but mostly your wasting your time and just prolonging the inevitable, but not by much.
Best bet is to pull the engine, tear down, and inspect everything and assess total damage completely, and repair as needed. Other than that, time and $$$ wasted, bigtime.
In my opinion, if you are looking to change bearings as a maintenance item, my advice would be to leave well enough alone-- especially a major repair such as bearings. When it breaks, then worry about it. With 250(kms) chances are much of the other engine parts are significantly worn, and may need complete overhaul.
Last edited by Daytrepper; 10-14-2006 at 01:11 AM.