Duramax LLY – ENGINE ASSEMBLY AND ADJUSTMENT – Crankshaft Main Bearing Selection

Main bearings are available in standard and two under sizes for select fit purposes. Required bearing clearances are:
• 0.0017-0.003 in. (0.045-0.083 mm) at bearings 1 through 4
• 0.002-0.0036 in. (0.055-0.093 mm) at number 5 rear main

There are three main journal diameter ranges. The ranges are identified by a color code paint mark near one of the journals. The size range color codes are blue, orange/red, and white. Rod bearing journals are marked yellow or green. The color codes indicate journal diameter and correspond to the Main Bearing Selection Chart at the end of this section.

The main bearing bores in the block are also coded for size. There are three ranges identified by the numbers 1, 2, or 3. These numbers are stamped in the cylinder block pan rail. Refer to the Main Bearing Selection chart at the end of this section.

NOTE: Different bearings are used in turbo and NA diesel engines. Do not interchange the main or rod bearings.


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