Useful Tips

Unscrewing a Broken Bolt or Stud from a Cylinder Block and Other Elements: Solving a Problem


During the repair, sometimes trouble occurs - something breaks. Sometimes a part breakdown leads to trouble with a large device. For example, a broken bolt in the cylinder block. A broken bolt causes a lot of trouble. Especially when it broke down in a place where access is limited.

Simple option

The first thing to do is not to panic. At all. A broken bolt can almost always be removed, the main thing is to act correctly.

Secondly, to inspect the "scene of the incident." If it breaks when unscrewing - we fill in WD40, with green or brake fluid - it is required that the broken-off piece okis on the thread. You can try to anneal the thread with a blowtorch - you need to look according to the circumstances. We look in what place it broke. When a broken piece sticks out above the part, it’s lucky - you can try to unscrew it. If this is possible, we wrap two nuts, fix the lower one with the upper one. We unscrew the lower nut - if the broken bolt left a whole thread, it should go out. There is not enough space for two nuts - we try to unscrew the pliers for the thread. Another way is to make the grinder a slot in the middle. As a result, we get a screw that you can try to unscrew with a screwdriver. If it works out, the problem is solved. But more often the bolt breaks either flush with the part, or inside it.

Removing a Broken Bolt

If broken at the part level - try to unscrew it with your finger. In fact, when a broken bolt is inside the hole on the thread, it is clean, and the screw just broke due to metal fatigue or because it was pulled earlier - it can just go from the finger. Or pay attention to the chip - when breaking off a piece on the break plane, a side always forms - we substitute the chisel, screwdriver - we try to unscrew it with light strokes.

Such cases often occur when a part without a thread is attracted with a stud or bolt - for example, a manifold to a cylinder block.

Difficult option

If it did not work out to unscrew in these ways - we will drill. The main thing is that the broken-off bolt is not red-hot. There are several ways that you must try before trying to drill a broken bolt. The most elementary - we take a drill with a reverse and a drill. Sometimes such a focus passes with a conventional metal screw, with a drill at the end. We click on the broken balance, we try to unscrew it with small turns, here we need accuracy - we need to twist “pull”. If these methods fail, we proceed to serious actions. When the diameter of the stud is small, you need to determine how to remove the chip - there is not enough space for the two options.

The first way. A small diameter drill makes two holes in the wreckage. One against the other. Drill shallow - about 5 - 10 mm, preferably away from the center. Then we take a lock ring puller, narrow-nose pliers or just insert two nails, clamp them with pliers - try to unscrew.

Bolt extraction technology

The second way. We need a special tool - an extractor. It is sold at tool stores. It is something like a cone drill, has a reverse thread, a very hard red-hot metal. First, we select a drill for its diameter. Carefully mark the center of the hairpin with the core, we need it to drill a hole. Deep is not necessary - just drill a little deeper than the length of the extractor. Then we wrap the extractor, trying to unscrew the broken piece.

When no method has helped, the most difficult option remains - to drill. To do this, you need several different diameters of sharp drills and a strong arm. The most important thing is to catch the center of the wreck. As accurately as possible we outline the core center, the accuracy of drilling depends on this. Then with the smallest drill we drill through the broken off.

It is important to drill exactly along the remainder, parallel to the wall, so that the alignment of the holes on both sides is observed. Then we take the next diameter of the drill and so on, until we get to the wall of the hole. If you missed a little with the center of the hole - it happens. The main thing is to stop in time, leaving a whole thread. We take a chisel, a screwdriver or a nail, crush the remainder of the fragment wall inward. Then we just pull the resulting lump out.

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

So, bolts and studs often “sour”, become rusty, can be tightened or twisted with a warp (not thread) during previous operations. This is true for all models and brands of cars, without exception.

In any case, a frequent situation is when, during the unscrewing of the bolt, the master breaks the thread, breaks the pin, breaks off the cap of the bolt, etc. It is also possible that the tightening torque during tightening is greatly exceeded, the bolt bursts, remaining under-twisted. Naturally, the remaining bolt must be unscrewed, after which the stud or bolt should be replaced.

One way or another, the most problematic situation is that the bolt can be broken flush, that is, unscrewing it in the usual way or using simple tools is not possible. 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, while the most common are:

  • bolt drilling
  • unscrewing the bolt by welding,

First of all, the choice of one or another method depends on some conditions. If the bolt was scrolling before the breakdown, then the main task is to “attach” to his body, then to unscrew the remains. If it is impossible to turn the bolt, then it is necessary to carefully drill the remains of the body in the hole. Let's look at the available methods in more detail.

To begin with, for a successful result, you need to know how to unscrew the ripped bolt, as well as perform a number of additional work before unscrewing.

  • At the initial stage, it is necessary to remove dirt, oil residues, rust, etc. from the problem area. It is also imperative that a special agent be applied to the threaded connection so that the bolts “become sour”. Special cleaners can be such a liquid. These are compounds that remove and soften rust, dirt, etc. Still for these purposes, WD-40 or pure oil is quite suitable.
  • We go further. If the chip protrudes above the threaded hole, several hammer blows can also be made through it, the bolt is additionally heated (for example, using a blowtorch). The only thing is that you can hit the bolt or warm it only if other parts, elements or the threaded hole itself are not guaranteed to suffer from such an impact.

Also in the wreckage, if the body protrudes high enough, a through transverse hole is drilled into which a metal rod, a nail, a screwdriver, etc. are inserted. Then the resulting lever allows you to twist the chip with the help of improvised tools.

  • Often the body of the bolt does not protrude much above the surface, that is, the bolt is broken almost flush. This complicates the process of removing residues from the threaded hole. In this case, welding helps well. To accomplish the task, it is necessary to select a bolt with a cap that is similar in diameter, then you need to weld it with a welding machine to the body of the debris in the threaded hole.

Next, you can try to unscrew the chip with the key. It is important to remember that welding can be fragile at the junction, so you should not put too much effort. We add that in addition to welding, special types of glue are sometimes used for such cases. At the same time, this method is not widespread, since these types of glue are not always at hand, and some doubts are caused by the reliability of fixation using such means.

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

First of all, you need to prepare a drill and a set with thin drills. Please note that without certain skills it is not recommended to do such work. The main objective is the need to drill several small holes in the body of the bolt. This is done so that then it becomes possible to connect these small holes into one big one. Next, a screwdriver is inserted into the hole, after which the debris is twisted.

Drilling is considered the last available method to remove a fragment of a bolt that has broken in a threaded hole. The method is quite complicated, requires special skills. The main goal is to not damage the thread of the hole itself when drilling the debris.

To drill a chip, first a hole is made in its center with a thin drill. Then the drill changes to a thicker, etc. After the walls of the body of the broken bolt become as thin as possible, they should be tried to be broken with a metal wire or tweezers. Then the debris is removed from the hole. This method, if implemented correctly, eliminates the need to cut a new thread in the hole or restore an existing one.

To summarize

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

The same can be said about tightening the studs or bolts. The fact is that you need to tighten the fasteners with a strictly defined effort and in the specified order (for example, tight cylinder head). Ignoring this rule often leads to the fact that the studs or bolts break, stretch, deform, etc.

In the event of such problems, it is better to contact experienced specialists who in many cases will unscrew the problematic torn or sour bolt. If it is not possible to avoid breaking the bolt, then qualified craftsmen will remove the remains from the hole with minimal risk, and if necessary, repair the damaged thread.

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Surface break

Usually this is the easiest option for damage and can be fixed without drastic measures, which can sometimes harm your car or other unit. However, before unscrewing the broken-off bolt, it is necessary to process the place of breakage with kerosene. This will help eliminate fumes and weaken contact surfaces. Next, you need to follow the following recommendations:

  1. With a sufficiently large protrusion, it is best to use the simplest tools such as clamps, pincers or pliers. With their help, it is easy to grab and turn the part along the thread without applying special efforts,
  2. When answering a question about how to unscrew a broken bolt, some masters advise using a welding unit. It will allow you to weld a lever to the hardware, which will help to unscrew or unscrew the connection by creating a rotational movement with the desired pressure,
  3. There is also an option in which you can use a drill with a diameter slightly smaller than the bolt itself. A hole is made in the center of the axis of the bolt to the entire depth. Then the rest of the fasteners are removed using a hook, twisting the thread from the bottom.

These are the most general recommendations, combined use of these methods is possible. These breakdowns are the simplest, they require only a little processing and the use of simple tools.

Cliff flush

This type of breakdown is considered the most difficult to repair, since it is very difficult to determine the diameter of the hole, especially when cutting fasteners. Therefore, in order to drill a broken bolt of a certain type, it is necessary to clean the surface. This will allow us to determine the gaps we need.

Often the following unpleasant situation occurs: the cliff site has curved shapes that are very difficult to process and straighten. And to drill a product in such a state is categorically not recommended, because there is a risk of permanently ruining the structure. Therefore, first you need to apply the core, which prepare the place in the center of the drill.

Further procedure, drillable a bolt broken in one way or another is similar to a variant with a surface break. After creating the hole, the remainder of the thread is removed with a hook.

Breakage of a bolt below the surface

Complicated fault, especially for a soft metal part. Therefore, it is very important to unscrew the broken bolt without damaging the thread in the hole. The procedure here is as follows:

  • The center of the hardware is being plotted using a core. It’s best to use a thin and durable metal tool, it will not damage the product,
  • Then a tap having a reverse thread is acquired. Its diameter should be smaller compared to the diameter of the bolt,
  • A not very deep hole for the tap is drilled,
  • A tool is installed to cut the thread. It is rotated in a circle and then the element can be unscrewed.

If the last point could not be implemented, then the tool can become directly a bolt. However, it is not worth making excessive efforts, as there is a chance of breaking it. As a result, you can remove the old broken part and spin new elements.

Using Extractor

However, the surest option that will help to unscrew a broken bolt is to use a special tool for this operation. It is called an extractor, it is sold in a set tools of different diameters. Outwardly, it looks like a tap, but there are no longitudinal slots on it and there is a conical notch for cutting.

You can use the extractor after you drill a hole in the center with a diameter that will allow the tool to go into several turns. Turn it all the way, and then until it is completely twisted.

So, here are some ways twisting broken bolt elements. Each of them should be used depending on the complexity of the breakdown and the availability of appropriate tools. But the most practical and optimal option is to purchase a set of extractors. They are quite practical and allow you to work with bolted parts of various sizes and with any type of thread.

It is imperative that surface treatment be carried out, this will eliminate unnecessary contact and contamination. Good job for unscrewing broken bolted joints, for the full-fledged operation of the whole mechanism depends on this, especially for cars! You can find out more about how to unscrew the broken off bolt elements using video on specialized sites or forums!

Types of Breaks

Typically, such fasteners break at the end of the thread, although there may be exceptions. As a result, the hardware itself can be deepened into the hole, protrude above the surface or even with it. Based on this, it is necessary to decide how to unscrew the broken bolt, paying attention to this very moment.

Surface cliff

This type of breakdown refers to the option when a part of the hardware protrudes above the surface. We can assume that such a task is most easily solved without using radical measures. However, before making any unscrewing of a broken bolt, it is worth treating the place with kerosene in order to eliminate carbon deposits and weaken the contact of surfaces.

  • If the protrusion is quite large, it is easiest to use tools such as pliers, pliers or clamps, with which you can grab the part and turn it out by thread.
  • Some experts, answering the question of what to do if a bolt breaks, which sits very tightly in the hole, recommend using a welding machine. С его помощью можно приварить к метизу рычаг, что в результате позволит получить большое плечо для вращательного движения.
  • Также можно использовать сверло диаметром немного меньше самого болта. Сверлом проделывают отверстие по центральной оси болта на всю глубину. После этого остатки крепежа извлекают при помощи крючка, стараясь выкручивать резьбу с самого низа.

Cliff below the surface

Such damage is quite complex, especially if the part itself is made of soft metal. Therefore, it is necessary to solve the problem of how to unscrew a broken bolt and at the same time not damage the thread in the hole.

First of all, with the use of a core, the center of the hardware is outlined. In this case, it is best to use a thin instrument made of durable metal, so as not to accidentally damage the part.

The next step is to purchase a tap with a reverse thread. Its diameter should be less than that of the bolt itself.

After that, a hole for a tap is drilled in the hardware itself, but they do not deepen it much. Next, just install the tool for threading and rotate it in the direction that will lead to twisting. If this did not happen, then the tool is used as an ordinary bolt, but you should not exert too much effort so as not to break it.


The most correct answer to the question of how to unscrew a broken bolt is the one in which they propose to use a tool specially created for this. It is called an extractor and is sold as a set of products of different diameters. Outwardly, it resembles a tap, but without longitudinal slots and with a conical notch for cutting.

To use the extractor, it is enough to drill a hole in the center with a diameter that allows the tool to go into several turns. Then they begin to crank it all the way, and then to complete twisting.

There are several options for removing broken bolts from the hole, which can be used for certain types of damage. However, it is best to pre-purchase a set of extractors that can be considered the best tools for such tasks.