When unscrewing fasteners, try to mark their original positions on the assembly. Often, screwing in the bolt and setting the washers in place immediately after removing the corresponding element avoids confusion during assembly. If this is not possible, all fasteners should be placed in a box specially prepared for this purpose, divided into sections and appropriately labeled, or simply in separate labeled containers. This approach is especially useful when working with elements consisting of many small parts, such as a carburetor, alternator, valve train, instrument panel or upholstery elements.
When disconnecting electrical connectors, it is recommended to mark both halves of the connector with pieces of masking tape with numbers written on them, this will allow you to easily dock the connectors.
Joints sealed with gaskets
On vehicles, sealing gaskets are used to seal the joints of the mating surfaces of two elements. They serve to prevent leakage of oils and operating fluids and to maintain overpressure or vacuum.
Often such gaskets are coated with a liquid or paste sealant before installation. Sometimes, over time or under the influence of elevated temperatures or pressures, such a strong «sticking» mating surfaces to each other, so that the separation of the elements becomes difficult. In many cases, successful disconnection «stuck» elements helps tapping them from the outside along the perimeter of the joint with a hammer with a soft striker. You can also use an ordinary hammer for this purpose, striking through a wooden or plastic spacer. Tapping should not be performed on castings and impact-sensitive parts that can be easily damaged by tapping. If this kind of difficulty occurs, first of all, you should check whether all fasteners have been removed.
Do not pry the elements with a screwdriver or pry bar inserted into the joint area, as this can easily damage the mating surfaces, which will further lead to the development of leaks. If the use of such «leverage» absolutely necessary, use a pen from the old mark for this purpose, but remember to carefully remove the resulting chips both from the mating surfaces and from the internal cavities of the elements.
After the elements are separated, their mating surfaces should be thoroughly cleaned with a scraper to remove traces of old gasket materials. Hardened fragments can be pre-softened with a rust converter or a special chemical composition.
Warning. Never use gasket remover or other harsh chemicals on plastic and composite components.
In this case, a piece of copper tube with a flattened and pointed end can be used as scrapers. Copper is recommended because it is generally softer than the materials being cleaned and this reduces the chance of scratching the surface. Some gasket residues can be easily removed with a wire brush, however, regardless of the method used, the mating surfaces should be completely clean and even. If for any reason the mating surface is scratched, fill the defects with gasket sealant before assembling the assemblies. In most cases, you should use a non-curing (or incompletely cured) sealant.