The situation when you need to pump tires, and the cap on the neck is dead, familiar to every motorist. This usually occurs due to the oxidation of the thread, ingress of moisture and reagents, or a banal “traction” during the previous installation. At the most inopportune moment, when the pressure sensor is on or you need to go to the track, such a trifle becomes a serious problem.
Attempting to tear off the sour part with bare hands or a standard key often leads to damage to the nipple itself or even the spool, which is fraught with depressurization of the wheel. Metal caps They are more prone to corrosion than plastic, but the latter can be alloyed with heat or chemical reaction threads. In this article, we will discuss professional dismantling methods that will help maintain the integrity of the node.
The main rule is not to use brute force immediately. A sharp jerk can break the thin brass leg of the nipel, and then a more serious replacement will be needed. There are proven chemical and mechanical methods to solve the problem without visiting the service.
Causes of corrosion and the mechanism of corrosion
Understanding the chemistry of the process helps you choose the right method of fighting. The main enemy here is the galvanic pair that occurs between different metals. If you have any. aluminum caps on a steel disc or brass noopel, in the presence of an electrolyte (water with salt), active corrosion begins. The resulting oxide layer works as a glue, filling all the micron gaps of the thread.
An additional factor is the temperature expansion. In summer, the disk and wheel elements are heated to high temperatures in the sun, in winter they freeze. These expansion and contraction cycles contribute to the destruction of protective coatings and close contact of surfaces. Plastic caps They can cling due to the aging of the material, which becomes brittle and sticky, or melting from the heat of the brake discs.
Often drivers themselves aggravate the situation by twisting the cap "to the point" with excessive effort. The thread on the nipel is very fine, and the pull creates excessive pressure in the turns, which in combination with oxidation makes dismantling almost impossible without prior preparation.
⚠️ Warning: Never ignore the absence of a cap after dismantling. Riding without the protection of the nipple will lead to rapid contamination of the spool and loss of pressure due to the loose fit of the valve.
It is also important to consider the quality of the products themselves. Cheap Chinese metal may not have any protective coating, starting to rust just a week after installation. Brass nipels They are more stable, but they do not last forever in the aggressive environment of road reagents.
Toolkit and training required
Before taking action, the workplace and tools must be prepared. Attempting to unscrew the cap on weight while the car is on the ground is doomed to failure and injury to the hands on the disc. First of all, the car should be securely fixed and, if possible, hang the problem wheel.
To work, you will need a basic set, which can be found in the garage or bought at the nearest car store. The key instrument will be passatia Or a specialized key for caps. If the cap is plastic and whole, ordinary pliers with wide sponges will fit, so as not to crush the body.
- 🛠️ Passenger or gas key - for grip and spin.
- 🧴 Penetrating lubricant (WD-40, "Liquid Key") is the main chemical solvent of rust.
- 🧤 Protective gloves - so as not to stain the hands with chemistry and not to hurt the sharp edges of the disk.
- 🔨 Hammer - for neat tapping (only for metal products).
Pay special attention to the choice of penetrating lubricant. Cheap WD-40s can be slow to operate. For highly oxidized compounds, it is better to use specialized sprays with high penetrating capacity, often containing graphite or Teflon. Brake fluid It is also sometimes used as a solvent, but it is aggressive to rubber seals and paint, so it should be used with extreme caution.
If there is no special spray at hand, you can use a mixture of kerosene and transformer oil in a ratio of 1: 1 - this folk remedy often works better than expensive chemistry.
Chemical method: use of penetrating lubricants
The safest and most effective way to start fighting a boiling cap is chemical exposure. Mechanical force without pre-treatment often leads to licking of the faces or breakage. Penetrating lubricant It is able to penetrate microscopic gaps due to the capillary effect, destroying the oxide film and creating a slippery film.
The processing process takes time and patience. Do not expect instant results after one slap. The algorithm of actions should be as follows: abundantly apply the composition to the junction of the cap and the nupel, trying to get the liquid to flow inside the thread. If the cap is metal and has holes, the lubricant will penetrate faster.
After application, you need to wait for a pause. The minimum exposure time is 10-15 minutes, but for older, highly corroded connections it is better to leave the car for 1-2 hours, periodically repeating the processing. You can do other things at this time, allowing chemistry to work.
| Type of instrument | Waiting time | Efficiency | Safety for rubber |
|---|---|---|---|
| WD-40 (classic) | 15-30 minutes | Medium | Tall. |
| Liqui Moly Rostlöser | 10-20 minutes | Tall. | Tall. |
| Brake fluid | 5-10 minutes | Tall. | Low (aggressive) |
| Acetic acid | 2-3 hours | Medium | Medium |
If after the first application the cap does not give in, do not rush to tear it by force. Repeat the lubrication procedure. You can slightly warm the connection site with a building hair dryer (not open fire!) to enhance the reaction, but only if the cap is metal and you are confident in the safety of the surrounding elements.
Mechanical impact and twisting
Once the chemistry has worked, we can move on to mechanics. It is important to distribute the effort correctly. If you just pull up or twist jerks, you can damage the nipple. There must be a reliable capture. For plastic caps, use wide-grab passesats, trying not to squeeze too hard so as not to crumble the plastic.
The movements should be twisting, with a small amplitude. Try to slightly twist the cap in one direction, then in the other, gradually increasing the angle. This will help to tear off the residues of oxides. If the edges are slimmed or the cap is metallic and smooth, it may be necessary to pipe-key or a vise, but you need to act carefully.
☑️ The twisting algorithm
In cases where the cap is stuck dead and standard methods do not help, you can apply the method of "loose". Carefully, without fanaticism, tap the end of the cap with a hammer through a wooden slot or dense fabric. Vibration will help the lubricant penetrate deeper into the thread and break down the tight rust joints.
⚠️ Note: When using a metal tool on a plastic cap, there is a risk of damaging the nipple itself. If the plastic has started to crumble, stop and proceed to drilling or using an extractor.
If the cap has decorative elements (logotypes, inserts), you need to capture the lower, metal or durable plastic part, and not for decoration. The decorative part will break off first, leaving the problem unresolved.
Radical methods: drilling and extraction
When the cap is so boiled that no chemistry takes, and the edges are already slicked or they were not originally, you have to resort to the destruction of the cap itself. This is an extreme measure that requires care so as not to damage the thread of the nipel. To work, you will need a drill and a set of drills for metal.
The essence of the method is to drill the center of the cap. Start with a thin drill, strictly in the center, then gradually increase the diameter of the drill. Your goal is to thin the walls of the cap to a minimum without touching the thread of the noose. When the walls become thin, the residues can be easily removed with tweezers or a screwdriver.
- 🔍 Centrification - You need to drill strictly on the axis, otherwise damage the nipple.
- 🛑 Depth limiter Use emphasis on drills or control depth visually so as not to go deep.
- 🌡️ Cooling - when drilling metal there is heat, let the tool cool down so as not to melt the plastic of the nickel.
There are special detachers for caps that work on the principle of an extractor. They are screwed or driven into a pre-drilled hole and when twisted, capture the remains of the cap from the inside. This is a more professional approach than just picking a screwdriver.
What to do if you damage the thread of a nipel?
If in the process of fighting you tore the thread on the nipela itself, it will have to be changed. To do this, remove the wheel, dismantle the tire (or squeeze the nipple without removing, if the tool allows), twist the old nipple and screw a new one. This requires a visit to the tire assembly if you do not have the skill to work with the cabin car.
After successful removal of the residues of the cap, be sure to blow the nipple with compressed air and check its performance. Pressing on the spool should put air out, and letting go - close the valve tightly.
Prevention and proper care
To the problem of "how to unscrew the boiling cap" did not arise before you in the future, you need to follow simple rules of prevention at each seasonal change of tires or scheduled pumping. The main enemy is the lack of lubrication on the thread. Before installing a new cap, the thread of the nipel and the inner thread of the cap is recommended to be lubricated.
Perfect for this purpose. graphite regular lithole. A thin layer of fat will create a barrier between the metal and oxygen, preventing oxidation. This will also make it easier to unwind in the future. Do not use solidol as it may coke over time.
Twisting the cap without bigotry. Enough tighten his fingers to a light stop, and then slightly add the effort key or passages, literally a quarter of a turn. Excessive force does not add tightness (for this the golden socket is responsible), but only contributes to the boiling.
Regular lubrication of the thread with graphite or litholic with each reshoes is a 100% guarantee that the cap will never boil dead.
It is also worth considering buying caps made of materials less prone to corrosion. For example, brass caps with a nickel coating or high-quality plastic models with a rubber seal inside last longer and are less prone to fuming than cheap silumine or zinc alloys.
FAQ: Frequently Asked Questions
Can I drive without a hat if it breaks off?
Short term, but not recommended. The cap protects the nipple from dirt, water and dust. Without it, the spool can become contaminated and stop holding pressure, or start poisoning the air. Try to install a new cap as soon as possible.
How to lubricate the thread so that the cap does not boil?
It is best to use graphite lubricant, litol-24 or special aerosols to protect threaded joints. The normal motor oil will wash away quickly, and solidol can harden.
Why is a metal cap better than a plastic cap?
Metal caps (especially brass) are stronger, better absorb heat and look more aesthetically pleasing. However, they are more prone to galvanic corrosion when in contact with aluminum disks, so they require mandatory thread lubrication.
How to unscrew the cap if all the faces are licked?
If the edges licked, it will not work to capture them with passages. You will need to either drill the cap with a smaller diameter drill, or use a special extractor, or try to heat it (if it is metal) and cool it sharply to break the thread.