When servicing any type of engine, if you have removed a cover or part that uses a gasket to form a seal to the engine, you will need to replace the old gasket with a new one each time. A quick job can fall apart though when it comes to removing an old gasket that may have hardened and "glued" itself to the surface of engine. There are a few simple tricks to removing an old gasket that will make the process go smoothly and quickly.
Use a flat head screwdriver to pry up the old gasket and pull it from the part. Do not dig with the screwdriver into the gasket, but if you can get the flat of the blade under to start it, do so and pull as much of the old gasket off as possible.
Saturate the remaining old gasket material with WD-40. The best way to do this is to completely cover it with the spray lubricant, wait a few minutes, spray the old gasket again and wait another few minutes before moving on to the next step.
Hold a razor blade at a 45-degree angle and begin to scrape the old gasket off.
Wipe the metal where the old gasket was with acetone and allow it to penetrate and remaining traces of the old gasket or residue left on the metal.
Gently scrape the metal with a razor blade again. Wipe it clean and dry with a cloth to completely remove any of the old gasket and residue.
