A ridge reamer is a specialty automotive tool designed to remove the ridge that forms at the top of the cylinder wall in an engine. This ridge can make it difficult to remove the pistons without damage. The ridge reamer is turned by hand and uses hardened steel or carbide blades to carve away the ridge, leaving the cylinder wall smooth and without obstructions. The ridge reamer is used on the engine block after the cylinder head has been removed.
Using regular motor oil (any weight will do), liberally lubricate the cylinder walls and the ridge reamer. This is a very important step. It's impossible to use too much oil.
Position the ridge reamer in the top of the cylinder bore. Set the reamer fully into the cylinder until the stops on the top of the ridge reamer bottom out against the top of the engine block.
Adjust the ridge reamer to the cylinder size. Adjustments vary with the make and model of ridge reamer.
Adjust the ridge reamer to the proper height. Again, adjustments vary with the make and model of ridge reamer. Begin cutting the ridge from the bottom and work your way to the top of the cylinder wall.
Using a wrench on the large hex at the top of the ridge reamer, turn it in the cylinder bore. Some ridge reamers turn clockwise, and some counterclockwise, so check the instructions for your particular model. Turn the ridge reamer one full revolution, then check the condition of the cylinder wall. When the ridge is gone or nearly gone, you are done. Relubricate the cylinder wall as necessary during this process.
Use a shop vacuum and a magnet to remove the debris from the cylinder bore before removing the piston.
