Measuring Crankshaft Bearing Clearances - Plastic Gage Method

Install the crankshaft bearings into the engine block.

Fig 1: Installing Crankshaft Bearings
Courtesy of GENERAL MOTORS CORP.
Install the crankshaft.

Fig 2: Installing Crankshaft
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Install the gagging plastic the full width of the journal.

Fig 3: Installing Gagging Plastic
Courtesy of GENERAL MOTORS CORP.
Install the crankshaft bearings into the crankshaft bearing caps.

Fig 4: Installing Crankshaft Bearings Into Crankshaft
Courtesy of GENERAL MOTORS CORP.
Install the crankshaft bearing caps in the original positions and with the arrow on the crankshaft bearing caps in the direction of the front of the engine block.

Fig 5: Removing Crankshaft Bearing Caps
Courtesy of GENERAL MOTORS CORP.
Install the crankshaft bearing cap bolts.
Tighten

Tighten the crankshaft bearing caps to 105 N.m (77 lb ft).
Remove the crankshaft bearing cap bolts.
Remove the crankshaft bearing caps. The gagging plastic may adhere to either the crankshaft bearing journal or the crankshaft bearing surface.
Without removing the gagging plastic, measure the compressed width at the widest point using the graduated scale on the edge of the gagging plastic envelope.

Fig 6: Measuring Remaining Crankshaft Bearing
Courtesy of GENERAL MOTORS CORP.

If the flattened gagging plastic tapers toward the middle or the ends, there may be a difference in clearance indicating taper, low spot or other irregularity of the crankshaft bearing or the crankshaft bearing journal.
Remove the flattened gagging plastic.
Measure the remaining crankshaft bearing journals.