Quote:
Originally Posted by KCM
I must respectfully disagree with this statement. All crankshafts are hardened at the journals. It is true that on occasion a manufacturer may not recommend grinding a crankshaft on a certain engine, but the majority of the time it can be done. For these engines, Mercedes does offer four different repair sizes, and the service manual gives specifications for "reconditioning" the crankshaft.
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Agreed.
It would be very unusual for a 1-2" diameter case-hardened part to have a case-depth less than .030".
Would not surprise me in the least to learn that the case is .050 or even a bit more. Not that anyone plans to grind their crank -quite- that far...
Also, I'm not comfortable with the repeated declaration of 'scoring' as a crank-killer. Over the past 30 yrs, I've rebuilt a number of engines (from 1-lungers to Cat D9 engines) that had 'damaged' cranks; and I've never found 'normal' scores or grooves to cause issues after a rebuild.
So long as any -protruding- metal is properly removed, and any 'loose' particles in the scores are cleaned out, the crank seems to do just fine. If you think about it, 2 or 3 scores of .010 - .020" is just a tiny tiny % of the total journal-area.
To my mind, the -real- issue with journal-damage is whether you have a -flat spot- or not. Such spots are usually caused by the 'beating' when the bearing lets go.
If the journal has any sorty of flat spot, it will act as a kind of 'pump', and will screw up the oil-film formation.
Also, out-of-round journals have a similar effect.
So in sum, I guess I'd say that minor scoring can be cleaned up by hand and likely not cause a problem....and just about any kind of damage or tolerance-issue that's less than .010" total can be fixed with a crank-grind.
The above has been my own experience anyway.
Best of luck with your project....I applaud you for taking up the challenge and pulling it down for a rebuild.
