Connecting rods move up in down in the cylinders of an engine in conjunction with the rotation of the crankshaft. Between each rod and the crankshaft is a connecting rod bearing. If the bearings are too small, the engine can overheat and wear prematurely. The engine can also wear prematurely if the bearings are too large. A product called Plastigage is used to measure bearings. If the measurement does not fall within the factory specification range, purchase bearings of a different size.
Instructions
- 1
Clean the rod bearing journals and the main bearing journals with a lint-free cloth and engine degreaser. Although these surfaces must be lubricated upon final assembly, they must be clean and dry when checking the rod bearings.
2Position a strip of Plastigage across the entire length of the middle of the bearing surface within the rod cap.
3Position the rod cap onto the crankshaft and tighten the cap to its factory torque specification, using a torque wrench.
4Remove the rod cap from the engine and invert the cap to expose the compressed Plastigage.
5Measure the width of the compressed Plastigage with the scale printed on the Plastigage envelope.
6Compare the measurement found in Step 5 with the factory measurement. If the measurement does not fall within the acceptable factory range, purchase either an undersized or oversized bearing.
