Home » Duramax LLY » Duramax LLY – CRANKSHAFT SERVICE


Clean the crankshaft with solvent and clear the journal oil holes with a wire brush if necessary. Dry the crankshaft with compressed air or lint free shop towels.
Inspect condition of rod and main journals (Figure 2-113). The journals must be smooth and free from scoring, grooves, taper, cracks, and checking/galling.

Minor nicks and burrs can be removed with an oil stone and 380 grit emery. Minor scratches, or scoring on journal surfaces can be smoothed with 320 grit emery followed by polishing with crocus cloth.

Check for cracks on all surfaces including the counterweights.
Also check the threads in the crankshaft flange and nose.
Rusty, rough threads can be cleaned up with a tap. However, replace the shaft if the threads are seriously damaged.
Magnaflux or Zyglo the crankshaft if cracks are suspected.
Although the crankshaft journals can be machine polished to restore surface finish, replace the crankshaft if damaged, distorted, worn, or scored. Do not attempt to salvage it.


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