If you need to disassemble and repair the gearbox, in most cases there is a violation of the integrity of the factory seals. It is not always possible to purchase a suitable gasket for a mechanical or automatic transmission, therefore it is necessary to seal in another way.
- The feasibility of using sealants
- Types of sealants for automatic transmission
- Silicone sealants
- Anaerobic Sealants
- Synthetic and ceramic sealants
- Sealant selection criteria
- Sealant Tips
- Sealant Overview
Most often, after partial or complete disassembly of the case, a special automatic sealant is used for automatic transmission, which will help to complete the car repair without extra costs.
The feasibility of using sealants
It happens that in an automatic transmission, oil starts to leak from under the gaskets. Such a malfunction is quite common among problems with the automatic transmission, so car owners are advised to regularly inspect the car on a lift or in a pit. Sealants can be used from oil leaks that have already been detected: they will successfully replace the gasket.
Also, it is necessary to disassemble and assemble the box in case of problems with the control unit, valve body, torque converter. During any repair, sealant is used for:
- lack of gaskets at hand or financial difficulties with the purchase of the original;
- the presence of deformations on one of the joined surfaces, which cannot be eliminated by laying;
- needs to additionally close the joint between the parts.
It must be remembered that for manual transmissions and automatic transmissions, greases of different compositions are used, into which unequal additives are introduced. Therefore, when buying a sealant, one must take into account the type of transmission, otherwise its composition will be poorly combined with the components of the lubricant.
to contents ↑Types of sealants for automatic transmission
There are many sealing materials that can be used for automatic transmissions. They differ in base, additional composition, operating temperature, and pour time. Sealants can have a different color, most often on sale are white, gray, black materials. Depending on the composition, the agents are divided into anaerobic, silicone, synthetic, and ceramic.
Silicone sealants
Silicone based sealants are most in demand in the assembly of automatic transmissions, since they are inexpensive, convenient, and easy to use. Initially, their consistency is liquid, but it does not flow and quickly hardens on the surface. Polymerization occurs when silicone comes into contact with moisture from the air, usually it takes 10-15 minutes. When working with large parts, you must act urgently, because the material can freeze even before the main components are fixed by the master. In this case, you will have to remove the seam and repeat the job again.
Silicone sealants have the following properties:
- flexibility, elasticity, plasticity;
- high strength;
- excellent adhesion to metal and plastic;
- heat resistance (up to +300 degrees), tolerance of temperature differences;
- oil resistance;
- ability to withstand high pressure.
Often, silicone sealant is used to seal the cover, automatic transmission pan. It easily closes gaps up to 5-6 mm thick of any length, fills cavities, defects.
The disadvantage of this tool is the need for thorough preliminary preparation of the surfaces, otherwise an effective connection cannot be achieved.
to contents ↑Anaerobic Sealants
This type of sealant is used as a replacement for silicone. This includes new generation products that freeze in the absence of oxygen. After applying the sealant, it is necessary to press the parts tightly against each other to create an airless environment: this way the seam will gain the necessary hardness.
The composition of anaerobic sealants contains dimethacrylate esters, which are polymerized without oxygen. This gives an advantage to the master, especially the novice: you can work with the composition without rushing, although if the open state is too long, dust and moisture can settle on the sealant layer, which will worsen adhesion. Advantages of anaerobic sealants are as follows:
- resistance to chemicals, oils;
- lack of damage during pulsation and vibration;
- tolerance of pressure, temperature drops;
- prevention of rust on metal;
- durability and reliability of the connection.
The disadvantage is the small possible thickness of the seam: it is allowed to apply a layer of only 0.5 mm. Otherwise, the sealing composition will not provide proper setting and sealing joints.
to contents ↑Synthetic and ceramic sealants
Artificial resins have become the basis for the development of the so-called synthetic sealants for automatic transmissions. Such compounds are highly elastic, tolerate moisture, the effects of oils, chemicals, UV radiation, and are resistant to mechanical damage. There is no need for thorough preliminary preparation of the base.
Ceramic sealants have a similar composition, only additionally include ceramic components. The latter contribute to a significant increase in heat resistance of the composition, as well as lengthening its service life.
Sealant selection criteria
When selecting a sealant, first of all, they find out what type of gearbox it is intended for. Those compositions that are suitable for mechanical transmissions are not worth buying for automatic transmissions. It is advisable to purchase high-quality material from a well-known manufacturer, which has all the necessary holograms, barcodes and other control data. A residual shelf life is necessarily assessed: if it is too small, it is better to refrain from buying.
Heat resistance is an important indicator of the quality of the sealant, because the seam will be heated during car driving. You should choose those products that do not deteriorate from the temperature within + 200 ... + 300 degrees or look at the recommendations of the machine manufacturer.
Typically, a small amount of sealant is required to repair the automatic transmission, so in most cases a 70 ml tube is enough. It is better to take the product with a dispenser and an elongated nose: it is more convenient to apply it. For large areas, sealants are bought in cartridges for a special gun.
Sealant Tips
To properly apply the sealant, you need to proceed in stages:
- Ground preparation. All parts and details that will be in contact with each other should be cleaned of any dirt and oil.
- Degreasing. Treat surfaces with acetone or alcohol, then wipe with a dry, clean cloth.
- Sealant preparation. Open the sealant tube. If it is in the cartridge, cut off the spout and insert the can into the gun.
- Application of the composition.Spread the sealant evenly on one of the surfaces, making a seam of the desired thickness, but not exceeding the maximum permissible. Make sure that the sealant does not come out over the edges of the seam by more than 1 mm.
- Further actions. Connect the parts, leave them to dry for at least a day. Then you can start operating the car.
to contents ↑
Sealant Overview
One of the most famous on the market are Permatex sealants in black packaging. For automatic transmissions, you should choose the Automatic Transmission RTV Gasket Maker composition, which gives excellent adhesion to metals, has high elasticity, has high oil resistance and guarantees protection of surfaces against oxidation. The tool works at -54 ... + 204 degrees, and for a short time period can be heated up to +260. The sealant is safe for health, does not contain toxic components, allows the application of a layer of up to 6 mm.
Another good sealant for automatic transmission pallets is manufactured by DoneDeal, its name is RTV Red Silicone Gasket Maker (red-pink packaging). per day.
Silicone-based Reinzosil sealant can be used at temperatures up to +250 degrees with short-term heating up to +300 degrees. It does not contain solvents and is used by craftsmen even in enclosed spaces. The product does not respond to oils, aggressive liquids, UV radiation, water. After curing, it allows you to get a flexible, elastic seam that retains properties throughout the entire period of operation.
The use of high-quality sealant in the repair of automatic transmission will save the user from the need to find suitable gaskets, make assembly of parts quick and help to obtain a reliable result.
