Crank machining required?

[maldotcom2]

Does a crank from a running engine need to be machined if new bearings are to be fitted? I was under the impression it only needed machining if the journals were damaged, but someone told me otherwise.

[Blown V6 Hatch]

I'd atleast get it linished (just a quick tidy up of the journals, not a machine). However, if they're good, you will get away with just bolting it in and checking the clearances.

[maldotcom2]

Would linishing require oversized bearings, or would that depend on the wear to start with?

[Blown V6 Hatch]

No, it won't require oversize bearings. Linishing is basically spinning the crank up in a machine and running some emery paper over the journals just to tidy them up a bit. If there is any heavy-ish grooves or marks in the crank linishing won't get rid of that, if it has heavy marks the crank will need a proper grind. So, it depends how good it is to start with as to how it comes up with a linish, but an engine shop will be able to tell you straight away if it needs a linish or a proper grind.