When working with Plastigage, three precautions should be taken, be certain that all the oils and greases have been washed out of the crankshaft as well as the bearing surfaces before testing, do not rotate the crankshaft while Plastigage is in place as it should be destroyed, and while stripping of Plastigage afterward, one should not harm the crankshaft or bearing surfaces which might have been coated with the said product and all the traces should be removed using only fingertips or a wooden stick Clearances of bearings must be examined every time when an engine is refurbished, this applies to the bearings that are intended for reuse, as well as to new ones, the procedure for checking clearances of main and connecting rod bearings is similar. It is advisable to commence with the paste by fitting of main bearings and caps to the engine housing once the crankshaft and bearing surfaces have been cleared. Apply Plastigage to main bearing journals, put on and properly torque down the main bearing caps, with their flats forward. Now, after the tightness you will have to release each bearing cap and check the flattened section of the Plastigage strip and using the scale present on the main body of the envelope, one will be in a position to see the amount of clearance present in the bearing. To perform checks to determine presence of out-of-round conditions, it is necessary to remove the Plastigage, rotate the crankshaft by 90 degrees and re-measure the new clearances which should be then compared with the old ones. For connecting rod bearing clearances, it is necessary to set each piston/rod assembly as above and to use Plastigage, while also measuring the connecting rod side clearance. If the bearings are within the range then they can be fitted whereas, if not, they should be removed and replaced with accurately standard bearings and it should be made sure that the upper and lower bearings are interchanged together.
