Unscrewing a broken bolt or stud from the cylinder block and other elements: solving the problem. How to unscrew a broken bolt in a hard-to-reach place How to unscrew a cut bolt

When screwing in the bolts, it sometimes happens that the head breaks off. If such a problem occurs, of course, the question arises of how to unscrew the broken bolt without damaging the parts connected by it.

The simplest case is when a protruding part of the thread remains above the surface. This scenario is quite favorable. All you need to do is take it and, having adjusted it accordingly, carefully unscrew the rod. To facilitate the process, it is sometimes used. It is applied to the protruding part. Then they take a hammer and lightly hit the fragment with it several times. This will help the lubricant penetrate into the threads. Then they wait 5-10 minutes and begin to remove the rod.

It is more difficult to cope with such a task as unscrewing a broken bolt that is broken flush with the surface or even below it. The key will not help here, since there is simply nothing for them to grab onto. However, nothing is impossible, you just need to be patient. This problem can be solved in several ways. All of them are quite complex and time-consuming, but quite doable.

You can try to unscrew the broken bolt by making a groove for a screwdriver at the end of the rod. A deeper slot is made under the usual one. A Phillips screwdriver has a larger surface area for adhesion, so it is not necessary to deepen the groove particularly deeply. This method is quite effective and in most cases helps solve the problem.

However, sometimes the rod jams tightly, and a screwdriver does not help. For the home craftsman, the question of how to unscrew a broken bolt remains relevant. The most radical way is to drill a hole in the rod for a bolt of a smaller diameter and cut a thread in it. To do this, you will need an electric drill with a set of drills of different diameters and a tap.

By screwing a small bolt into the fragment and applying it, you can easily deal with the problem. This method works in most cases. The only thing it is advisable to remember is that the thread inside the rod must be reversed. You need to drill the hole very carefully, exactly in the center. Otherwise, when unscrewing, the thread can easily be torn off.

A broken nail, screw or pin is removed in the same way. The bolt or other fastener comes out easily to the surface. In the most extreme case, the hole is gradually widened, using drills of different diameters (from smaller to larger) until the steel walls of the rod become very thin. After this, they can be broken and pulled out with tweezers.

There is another fairly simple way to unscrew a broken bolt with a recessed rod. You just need to weld the fragment using a nut. Its diameter must be at least 1 mm larger than the diameter of the rod. It is necessary that it warms up well and expands in time. The resulting knot is watered with cold water. After everything has cooled down, carefully unscrew the fragment.

We hope you have received the answer to the question of how to unscrew a broken bolt. We wish that in the future all bolts, screws and studs can be easily screwed in and out without breaking.

Among detachable connections, threaded ones take first place both in terms of prevalence and reliability. However, in practice there are many cases when it is not easy to unscrew a threaded pair.

Reasons why it is not possible to unscrew a stuck nut (bolt).

There are several reasons why disassembling this simple connection may be difficult or even impossible:

• deformation of the thread or connection parts, for example, due to a strong impact;
• screwing not according to the thread with the application of significant force - in this case, friction between the surfaces of the parts increases significantly (the effect can be aggravated due to the influence of external factors);
• oxidation of the surfaces of connection parts, formation of a layer of rust on them;
• diffusion of materials between joint parts.

The last two reasons are well known to almost everyone, especially motorists.

The problem is that studs, bolts and nuts are most often made of carbon steel. With prolonged contact with water and atmospheric oxygen (for example, wheel bolts are constantly exposed to this effect), these substances penetrate into the smallest gaps, including between the parts of the threaded connection. As a result, the iron oxidizes and a layer of rust forms, which increases friction. It will take enormous force to move the parts out of place (often the magnitude exceeds the strength of the bolt, and it collapses).

Designers try to prevent such troubles by using parts with protective coatings or made of stainless steel for connections. But this doesn’t always work. If a bolt and nut are exposed to heat (an example would be parts on a muffler), the protective coatings may be damaged and corrosion processes will accelerate.

There is also a process of diffusion (mutual penetration) of materials; the parts form a monolith, which becomes difficult to disassemble (those who try to unscrew a bolt on the crankshaft often encounter this phenomenon).

How to unscrew a stuck bolt (nut) - basic methods.

To cope with this task, several methods are used. They can be roughly divided into

• mechanical;
• physical;
• chemical.

Mechanical methods.

These include methods that allow you to disassemble a threaded connection by applying mechanical forces:

• the use of ring wrenches and socket heads instead of open-end wrenches;
• using leverage to increase effort;
• impact with variable direction of force;
• accentuated impact (short-term application of significant force or forces at certain points);
• impact destruction of layers of oxides and rust.

An open-end wrench covers only three edges of the nut or bolt head. In addition, there remains some gap between it and the edges. In this case, applying sufficient force to unscrew it may be a problem - the key may break off and “lick” the edges. A spanner or socket spans all edges, allowing greater force to be applied.

To increase the force, you can use a lever to increase the length of the handle. In this case, there remains a danger of licking the edges or destroying the fastening parts. You can also damage those parts that were connected by a threaded pair.

Often, changing the direction helps to unscrew a stuck or rusted nut - before unscrewing the connection, try to screw it in. The impact of forces alternately in different directions destroys the layers of rust, allowing the connection parts to move.

An example of applying significant force for a short time is provided by the method using a chisel and hammer. They make a notch on the edge, place a chisel against it (directing it as the nut is unscrewed) and hit it with a hammer. In this case, the impact force is much greater than what can be applied using a wrench. Since the impact is short-term, it cannot destroy the bolt.

For your information! This method can also be used to unscrew a nut with torn edges. This is somewhat easier than trying to cut new ones to fit a smaller key size.

Lightly tapping a nut and/or bolt with a hammer causes the entire structure to shake and destroy the rust layer. You only have to dose the impact force so as not to damage the parts or deform the thread. Although one of the methods for disassembling a “recalcitrant” connection is destroying the nut with such blows. The only problem is that the threaded pair will have to be changed.

Physical methods.

Some of them are based on the physical properties of metals. Of these, only one is widely used - heating the connection parts. At the same time, the material of the nut expands, the gap between it and the bolt increases, and it becomes easier to unscrew it. If you heat up the entire structure, you can destroy the rust that has formed, which will also give a positive result. For this purpose, you should use any heat source - a powerful soldering iron, a hair dryer, a blowtorch or other sources of open flame.

Important! Using an open flame near wood, flammable plastic or flammable liquids is dangerous!

Electric heating is a good replacement for open fire. For this, a transformer (factory or homemade) with a secondary winding with a voltage of 1.1 - 1.5 V and maximum current is suitable. Through copper cables and clamps, the secondary winding is connected to a bolt that must be unscrewed. Warming up occurs, after which the transformer is turned off and the connection is dismantled.

Other physical methods use the method of wetting surfaces to reduce friction. For example, if you allow liquid to penetrate the space between a bolt and a nut through the smallest channels, the friction between the threads will decrease and the pair will become easier to disassemble.

Of the easily penetrating liquids, you can use those that are always at hand for the motorist:

• brake fluid;
• antifreeze;
• kerosene;
• gasoline;
• diesel fuel.

The first two contain glycols and ethers - substances with enormous penetrating power. The rest are aliphatic hydrocarbons and have a similar effect.

The second group also includes solvents such as white sprit and turpentine. All of them can be used to unscrew a stuck nut. The processes differ somewhat only in time.

The method is simple - wet a rag and place it on the stuck parts. Penetrating into the gaps and pores, liquids lubricate surfaces and loosen layers of rust. After some time (from half an hour to 3-4 hours), you can try to unwind the connection. If disassembly fails, repeat the process. You can speed it up by periodically light tapping.

These same liquids are the basis for “liquid keys” - lubricants of a special composition that are offered in car dealerships.

One of the most popular among car enthusiasts is WD-40, which contains mineral oil, white spirit and highly volatile gasoline. The effectiveness of this “cocktail” has been tested in practice; it can remove rusted nuts in half an hour.

For your information! If the nut becomes stuck not due to water contact, but under the influence of temperatures, the effectiveness of WD-40 is significantly reduced.

Chemical methods.

Their action is based on the chemical destruction of rust formed between the connection parts. To do this, it is necessary that active chemicals get into the gaps between the bolt and nut.

Almost any acid is used for this treatment of threaded connections:

• sulfur;
• salt;
• vinegar;
• lemon;
• orthophosphorus, etc.

Sulfuric acid for battery electrolyte or hydrochloric acid for soldering radiators is used in this way:

• a rim is arranged around the nut or bolt head made of plasticine;
• A few drops of acid are added inside the resulting “container”;
• a piece of zinc activates the process, creating a galvanic couple.

A day after the start of such treatment, any connection unwinds.

Weaker acids are less effective and require either a significant amount or more time.

For your information! Phosphoric acid is found in drinks such as Coca-Cola. That is why you can try to unscrew the nut with their help. But its concentration is low, the acid itself has low activity, so such treatment is effective only in “mild” cases.

If all else fails.

If you still fail to unscrew the nut, the connection can be destroyed by cutting it off with a grinder.

Another method is to drill out the bolt with a drill.

But before resorting to such methods, you should evaluate all the consequences!

Video.

Very often, an old bolt that has not been unscrewed for a long time becomes almost “tightly” stuck to the thread. If you apply excessive force when unscrewing such a bolt, it may simply break. A rather complicated situation arises that can confuse even an experienced master. How to get a broken bolt if there is nothing to grab it with?

First, you should fill the broken bolt with some kind of lubricant, and, if necessary, a rust dissolving agent. After this, the bolt is tapped several times well with a small hammer so that the liquids better penetrate deep into the threaded connection. This simple treatment will make unscrewing the bolt much easier.

So, a broken bolt cannot be grasped by any tool if it breaks below or flush with the surface. In such a situation, you can drill a small slot for a screwdriver. To do this you only need a small drill.

Using such a drill, a series of holes are made, and then the partitions between them are broken out. The result is a groove where a screwdriver is inserted and the bolt is unscrewed with its help. At the same time, there is strong pressure on the screwdriver from above. And to make it easier to unscrew the bolt, the screwdriver can be clamped with a key.

If this method is not suitable, you can glue it with an aggressive glue based on strong acids or weld a metal rod, handle or other bolt to the broken bolt. This will make it quite easy to unscrew, but it is not always possible to glue something to it with sufficient reliability, and welding may not be available, so this method is not used too often.

The third method is to first drill a hole in the bolt, then make a thread inside it (reverse orientation), and then screw another bolt inside. The other bolt will be slightly smaller, but that doesn't matter. The most important thing is that now you can easily unscrew both bolts.

And the last thing you can do if all else fails is to completely drill out the bolt. To do this, use several drills. They start drilling the bolt with a fairly thin drill, but gradually move on to an increasingly larger one.

As a result, the walls of the bolt will become thin and they will simply break. It is not a problem to remove pieces of a broken bolt using tweezers.

This method of coping with the task always works. But there is one subtlety that should be kept in mind all the time. A broken bolt must be drilled strictly in the center.

If the hole is offset from the center, then by the time the bolt is almost drilled out, the thread will be damaged on one side, and on the other side there will still be a rather thick wall that is not so easy to break. If you drill the bolt strictly in the center, such a problem, of course, will not arise.

When you repair a car, anything can happen. Sometimes, in addition to direct repair tasks, “additional” ones of various kinds should be performed. A prime example of such a cumbersome puzzle would be dealing with a broken bolt. In fact, extracting one is not as difficult as it might seem at first glance.

1. Using a hammer and slotted screwdriver

A simple, but unfortunately not always applicable method. If, when a bolt breaks, there is a fragment sticking out that you can press against with a slotted screwdriver, then unscrewing it will not be difficult. We place the tool and begin to gently tap it with a hammer in the direction of unscrewing it.
You can also use a chisel instead of a screwdriver. In this case, you will have to put in even less effort.

2. Using a core and hammer

The core will allow you to unscrew the bolt if it breaks below the head or at the thread itself. We rest the tool in the place where the bolt breaks and begin to exert pressure on it with a hammer. After several blows, an unevenness should appear, which can later be grabbed with pincers or pliers.

3. By welding

The fastest and most effective way to remove a broken bolt. The only “but” is that this method requires a welding machine. The method is suitable for cases where the unfortunate hardware has a protruding area. The essence of the method is to weld a nut onto it, and then unscrew the piece with a regular wrench.

4. Using an extractor

Finally, to remove a broken bolt, you can simply use an extractor specially designed for this purpose. First, a hole punch is made in the bolt, after which the tool is inserted into its center. The extractor is screwed in until it stops, and then unscrewed along with the bolt.

5. Using drilling

The most time-consuming and desperate way to get rid of a broken bolt, which, nevertheless, is worth keeping a note of. Use the method only if everything else has failed.

First, a hole is made in the center of the fragment using a thin drill. After this, they begin to slowly expand it until only a thin threaded wall remains of the bolt. The remaining metal is carefully broken and removed from the hole.

Continuing the topic and more.

In the process of repairing and servicing a car, as well as any other equipment, there is often an urgent need to remove individual elements or the chassis, body panels, etc. At the same time, removing the engine components and suspension is often the most problematic operation. The reason is that the units can be tightened with bolts or studs, and the tightening torque is quite large.

If we add to this temperature changes in the engine compartment, oiling, accumulation of dust, dirt and other deposits, it becomes clear that unscrewing various bolts and other fasteners is not only a responsible and time-consuming, but also often a difficult task. In this article we will talk about what you can do if a stud or bolt breaks, as well as how to unscrew a broken bolt.

Read in this article

The bolt thread is broken, the pin is broken, or the bolt in the engine block is broken: how to unscrew it

So, bolts and studs often “sour”, become covered with rust, and can be overtightened or twisted skewed (not along the threads) during previous operations. This is true for all car models and brands without exception.

In any case, a common situation is when, while unscrewing a bolt, the master stripped the thread, broke the pin, broke off the bolt head, etc. It is also possible that the tightening torque during tightening is greatly exceeded, and the bolt bursts while remaining unscrewed. Naturally, the remaining bolts must be unscrewed, after which the stud or bolt should be replaced.

As a rule, bolts break in cases where the bolt is rusty or stuck, and too much force is applied when unscrewing. This usually affects used cars or cars that are used in difficult conditions. Often, threaded connections begin to create problems as a result of contact with moisture. For the chassis of the car, such contact is inevitable. In the case of an engine, the cylinder head is screwed to the cylinder block, the tightening torque is large.

One way or another, the most problematic situation is that the bolt can be broken flush, that is, it is not possible to unscrew it in the usual way or using simple tools. In other words, the “body” of the bolt does not protrude above the surface. In this case, there are several ways to solve the problem, with the most common being:

• drilling a bolt;
• unscrewing the bolt by welding;

First of all, the choice of one method or another depends on certain conditions. If the bolt was twisted before breaking, then the main task is to “attach” to its body in order to then unscrew the remaining parts. If it is impossible to turn the bolt, then you need to carefully drill out the remaining body in the hole. Let's look at the available methods in more detail.

Let's start with the fact that for a successful result you need to know how to unscrew a broken bolt, as well as perform a number of additional works before unscrewing.

• At the initial stage, it is necessary to remove dirt, oil residues, rust, etc. from the problem area. It is also necessary to apply a special agent to the threaded connection so that the bolts “deoxidize”. Special cleaners can use this liquid. These are compounds that remove and soften rust, dirt, etc. WD-40 or pure oil is also quite suitable for these purposes.
• Let's move on. If the fragment protrudes above the threaded hole, you can also hit it several times with a hammer, the bolt is additionally heated (for example, using a blowtorch). The only thing is that you can hit the bolt or heat it only if other parts, elements or the threaded hole itself are not guaranteed to suffer from such an impact.

If the thread has been broken off (the bolt is spinning), then the broken bolt is unscrewed using pliers, an adjustable wrench, etc. You can also use a chisel, a hacksaw or a grinder to make a “groove” on the body of the bolt, after which you can try to unscrew the piece with a regular screwdriver.

Also, in the fragment, if the body protrudes high enough, a through transverse hole is drilled into which a metal rod, nail, screwdriver, etc. is inserted. Then the resulting lever allows you to unscrew the fragment using available tools.

• Often the body of the bolt does not protrude much above the surface, that is, the bolt is broken almost flush. This makes it difficult to remove residue from the threaded hole. In this case, welding helps a lot. To implement the task, you need to select a bolt with a head of similar diameter, after which you need to weld it using a welding machine to the body of the fragment in a threaded hole.

Next, you can try to unscrew the fragment using the key. It is important to remember that welding may be fragile at the joint, so you should not apply too much force. Let us add that in addition to welding, sometimes special types of glue are used for such cases. However, this method is not widely used, since these types of glue are not always available at hand, and the reliability of fixation using such means raises some doubts.

• The most difficult case is considered to be a broken bolt that breaks off, for example, flush with the surface or even lower. Often this situation can be encountered when a bolt breaks off. In this case, the methods described above do not always work. To solve the problem, you need to know how to unscrew debris from a hole, drill a bolt from a car engine block, etc.

First of all, you need to prepare a drill and a set of thin drills. Please note that it is not recommended to perform such work without certain skills. The main task is the need to drill several small holes in the body of the bolt. This is done in such a way that it then becomes possible to connect these small holes into one large one. Next, a screwdriver is inserted into the hole, after which the fragments are unscrewed.

A more complex method is to cut a left-hand thread in the body of a broken bolt. In this case, you need a drill and a tap. First, a hole is drilled in the body of the fragment, then the left-hand thread is cut with a tap. Then another bolt is screwed into this thread. After such a bolt is screwed in completely, the fragment should begin to unscrew from the hole.

The last available method for removing a piece of bolt that has broken in a threaded hole is drilling. The method is quite complicated and requires special skills. The main goal is not to damage the thread of the hole itself when drilling out the fragment.

To drill out a fragment, first make a hole in its center with a thin drill. Then the drill is changed to a thicker one, etc. After the walls of the body of the broken bolt become as thin as possible, you should try to break them using metal wire or tweezers. The debris is then removed from the hole. This method, if implemented correctly, eliminates the need to cut a new thread in a hole or restore an existing one.

Let's sum it up

As you can see, there are several ways to unscrew a broken bolt or stud. Moreover, in each case, it is necessary to separately take into account in advance the nature of the broken body, the location of the fragment itself, the possibility of access to the problem area, the possible consequences of heating the remains of the bolt, etc.

Finally, we note that before unscrewing the bolts, it is advisable to carry out treatment to remove dirt and soften rust before starting the procedure. Moreover, if various standard methods of unscrewing do not give the desired result (the bolt does not fit), then it is optimal not to make much effort so as not to break the stud.

The same can be said about tightening studs or bolts. The fact is that fasteners must be tightened with a strictly defined force and in the specified order (for example, covering the cylinder head). Ignoring this rule often leads to studs or bolts breaking, stretching, deforming, etc.

If such problems arise, it is better to contact experienced specialists who, in many cases, will unscrew the problematic broken or soured bolt. If it is not possible to avoid breaking the bolt, then qualified craftsmen will remove the residue from the hole with minimal risk, and, if necessary, restore the damaged thread.

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