DIY cylinder head crack repair

In detail: DIY repair of a cracked cylinder head from a real master for the site my.housecope.com.

In the cylinder head, cracks occur due to mechanical damage and a violation of the temperature regime, overheating or freezing of antifreeze. The cylinder head cannot be repaired if a crack passes through the cylinders or valve seats. In other cases, repairs are possible. Consider 4 repair methods.

Before considering, it is worth noting that self-repair of the cylinder head is possible only with special equipment and the appropriate skills. In all other cases, you need to promptly seek help from a professional service, for example, OEM-Service. Otherwise, the crack can grow and lead to more serious damage.

In the case of a cast-iron block, the crack is drilled from the ends with a 5 mm drill, and cut along the length with a chisel at a right angle to a depth of 0.8 of the wall thickness.

Immediately before welding, the head of the block is heated to 600 degrees, a continuous layer of metal is welded using a gas torch and a cast-iron-copper rod, the thickness of the protrusion should not exceed 1-1.5 millimeters.

At the end of brewing, the block is smoothly cooled using an oven. The crack can be welded without additional heating of the block; for this, electric welding is used. The remaining weld bead is epoxy coated for additional protection.

The required surface of the block is processed with a metal disk-nozzle on an angle grinder or a drill, and the ends of the crack are drilled with a drill with a diameter of 3-4 millimeters. The holes are threaded for repair plugs made of copper or aluminum.

Video (click to play).

The repair plugs are screwed in flush, and the crack is cut at an angle of 60-90 degrees with a chisel to a depth of 0.8 of the block wall thickness. In the area of the crack, along the surface, notches are created with a chisel, after which the surface is degreased with a solvent.

Epoxy resin paste is applied in two layers, each layer at least 2 millimeters thick. To harden the paste, wait about a day, then finish the surface with a grinding machine.

We perform preliminary preparation of the crack surface, similar to the previous method. A glass cloth patch 0.2-0.3 mm thick is applied to the first layer of the applied epoxy paste. Each subsequent layer of epoxy and fiberglass should overlap the previous one by 1-1.5 cm on each side. In total, up to 7-8 layers are applied.

Both ends of the crack are drilled with a drill with a diameter of 4-5 millimeters. With the same diameter we drill holes along the entire crack with distances between the holes up to 6-8 millimeters. A thread is cut in the holes with a tap and copper inserts are screwed in, leaving protruding ends up to 1.5-2 mm high on the surface.

Then new holes are drilled between the already installed pins so that the new holes overlap the old ones by 1-2 millimeters. Similarly, pins are screwed into them, obtaining a continuous strip of pins connected to each other.

The ends of the pins are riveted with a hammer, thus creating a seam. From above, the seam is additionally coated with epoxy paste.

Hello! Cracks in the engine block are, of course, very sad, and such a malfunction can form absolutely at any time!

It is advisable to diagnose and eliminate such malfunctions immediately and without delay. Cracks can be removed well by welding.Therefore, I want to ask, is it possible to weld cracks in the cylinder head? How severe should the faults be? Are there any rules for welding?

Cracks can be closed by welding only under conditions:
1. Sizes of cracks. Of course, only small cracks are repaired. Large ones are usually rare. And usually the part is unsuitable for repair and further operation.
2. Cracks are not welded in the cylinder mirrors, valve seats, as well as at the joints of the block and the cylinder head.

Cracks in the cylinder head are electroweldable. The ends of the crack are drilled and grinded. This is done in order to avoid its further growth. Next, using an electric welding device, we put a weld into the recess.

What if there is a crack in the cylinder head between the valves? Should you brew yourself? Maybe it would be much safer to go to a service center?

Incidentally, I completely agree with you. Do not handle the cylinder head with your own hands. By the way, what can the boss crack from? As a rule, from sudden changes in temperature, as well as if cold water was poured onto an overheated engine.

Cracks of the size and location that you have shown can be completely repaired by yourself without resorting to the help of auto repairers. In this case, electric welding and pre-drilling are applicable. You will also need flux and a metal substrate for welding.

If the crack width does not exceed 0.1 cm (and with this width it will not be long), then it should not be welded. For one simple reason that during welding the quality of the metal decreases and cracks may form around the weld!

There are several methods for eliminating cracks in the internal combustion engine block:

1. Electric welding with hardening of the crack edges. In principle, they figured out what it is, I agree, correctly described; =)

2. Copper electrode + epoxy resin. Used when welding a metal patch to the crack. The size should be more impressive. Welding takes place with electrodes, and epoxy as a reinforcing component is placed on the seams;

3. Epodoxide resin. We just cover up the cracks and heat it;
4. Epoxy + fiberglass. Used as a patch, good to apply. If the crack is cobweb;

5. Method of pins. We drill holes along the entire crack at a distance of 5 mm from each other. We screw in the copper pins, and then bend them together. The resulting metal layer is coated with epoxy resin.

The latter method of elimination with pins is not very effective. And it gives off the Soviet past. It is much easier and faster to weld the crack.

I disagree with you. It was the last method that seemed to me the most successful. The main thing in it is accuracy, which consists in cutting pins of a certain thickness and carefully drilling them in. Putting only epoxy resin will not give any results at all, the composition will quickly fall off.

One of the most important steps is degreasing and cleaning the surface. If this is not done, then the resin will naturally fall off, and the welding will be done poorly. This is the first rule.
Second: we do it slowly and take our time. I myself welded a crack in the cylinder head, even on the previous car. The welding process itself took minutes, most of the time was spent on preparation and ...
Third: cooling. The most important process. Cool very slowly, otherwise the weld will become very fragile!

Among the breakdowns of the internal combustion engine, it is worth noting the appearance of cracks in the cylinder block and cylinder head. Such cracks in the engine casing and other component parts are quite common. During operation, many components in the structure of the internal combustion engine are subjected to serious mechanical and thermal stresses, which create natural wear and tear of the power unit.The block also cracks as a result of accidents, the walls of the cylinder block or the cylinder head can be punctured by engine parts (connecting rod, etc.) as a result of seizure of the power plant.

Blocks and heads of engine blocks are composed of various metal alloys. Technologies existing today often make it possible to restore damaged elements. Next, we will look at ways to eliminate the breakdown and answer the question of how to remove cracks in the cylinder block and repair cracks in the cylinder head. In some cases, repair of cracks can be done by hand.

One of the most widely used methods of eliminating cracks in the cylinder block and cylinder head is the sealing of defects in silumin and cast iron blocks by welding.

The following methods are used to detect cracks:

ultrasonic detection method;
use of magnetically sensitive equipment;
pneumatic crimping method;
search for cracks by means of hydrocontrol;

In practice, the detection of cracks in many car services is carried out by pumping air or water into the faulty element of the engine. In the case of air, the part is additionally immersed in a bath and defects are found by bubbles. If water is pumped into the element, then the need for immersion is eliminated, since cracks are diagnosed by fluid seepage.

To determine the exact boundaries of the crack, a pair of magnets are attached on both sides of the split, the space between the magnets is covered with special conductive sawdust. The presence of a crack will cause the lines of the magnetic field to break, sawdust will partially cluster on the surface of the split. This method allows you to clearly identify a crack in the cylinder block or cylinder head.

It should be noted that splits should be eliminated in strict accordance with all recommendations. Residual mechanical stresses in the seam zone can lead to violations of its integrity and the need for repeated repair.

The cast iron block is repaired by drilling the ends of the crack and then grinding the entire length of the split at a 90 degree angle. Drilling is necessary in order to prevent further spread. When it comes to welding, initially the cylinder block heats up to 650 degrees Celsius. After that, a continuous seam is applied using a filler cast iron - copper rod and flux. The final stage is the gradual cooling of the part, which requires a special oven.

In order not to warm up the block, you can use electric welding and copper electrodes in a tin wrapper. At the end, the surface of the resulting joint is degreased with acetone and an additional layer of epoxy paste is applied with a special spatula. Epoxy cures within 24 hours at room temperature and about 2 hours when heated to 100 degrees Celsius. The final stage will be grinding the processed seam.

To begin with, minor cracks can also be repaired by using epoxy paste and fiberglass. Before starting work, the metal surface must be well degreased. Layers of paste and glass cloth alternate during application, the last layer should be epoxy.

Among the technologies most in demand today, it is also worth noting a solution called SEAL-LOCK. The advantages of this method include the absence of the need to dismantle the engine. The method is suitable for repairing serious holes or cracks in the cylinder block. Also, the repair does not require the use of a welding machine.

The method is based on filling the crack with a special layer of soft metal, which, as a result, is securely attached to the surface of the part being repaired.

Riveting the seam allows you to eliminate possible voids, and also accelerates the diffusion of rivet and part materials. The result will be the appearance of a plastic seam that has a strong bond with the surface.Such a seam has a number of advantages over a welded seam:

does not suffer from temperature extremes;
able to maintain integrity under high temperature operating conditions;
does not receive significant stress;

As for the installation of large patches, with which you can literally "glue" a cracked engine block or a block head, then the solution method according to the implementation scheme resembles that described above.
You will need to cut and fit a patch of metal, after which it is installed by filling the entire perimeter with ties and conical plugs. The subsequent check of the finished seam for tightness is carried out using pressure testing under a pressure of about 6 atmospheres.

A crack in the cylinder head occurs as a result of improper engine operation due to overheating and a shift in stresses in the metal.

Cracks can appear in different places, hence the different consequences. It is generally believed that when the head is punctured, white smoke comes out of the exhaust pipe, but this is only one special case. A crack in the head can occur between different channels, therefore, the signs of a crack in the cylinder head will be different.

Next, we will consider some cases of cracks between the cooling system and other engine systems.

Oil system- when mixing oil and antifreeze, an emulsion appears in the engine instead of oil, a whitish foam, like a biscuit dough, and an oil film forms in the expansion tank of the cooling system.

Inlet channel- if coolant starts to get into it, then first of all it will wash the pistons to a shine, you can look through the spark plug hole, - the pistons will be like new. And when it enters the combustion chamber, this is just the case when white smoke can go from the exhaust pipe, although it is not a fact that it will go.

With release channel- then the coolant will simply fly out into the pipe in the form of steam. The engine constantly releases steam and it is unlikely that it will be possible to notice anything in this case, it will be simple to leave the liquid from the tank. Most likely, there will not even be a smell of exhaust gases in the reservoir.

With combustion chamber- through the crack, part of the liquid will go into the combustion chamber, but a very small amount, all due to the pressure difference. In the engine, during the combustion of fuel, a large pressure is formed, and the exhaust gases through this very crack enter the cooling system, increasing the pressure in it. Because of this, the pipes swell, and the tank stinks of exhaust gases. But the liquid can also go into the combustion chamber - the cooling system is still under pressure, but a vacuum has already gone into the combustion chamber and air has begun to be sucked in. Due to the difference in pressure, coolant begins to seep into the combustion chamber. A sign of such a crack will be clean pistons (not always), a smell in the tank, elastic pipes and a cold stove radiator (airlock).

Car manufacturers allow head cracks to form and this will not be considered a malfunction, as the crack will be shallow and will not connect the two containers. In VW diesel engines, a head with a crack between the valves is allowed for use.

But finding all the cracks is a problematic task even for an experienced minder. It would seem that on the same motors, cracks should form in the same places. But this does not make the search easier. There are places that can be found with one glance at the head:

—between valves- the crack is immediately visible, passes under the seats of two adjacent valves.

—between the spark plug and the valve- the same situation, again, everything is in plain sight and you don't need to look anywhere

—in diesel engine the crack can go from the valve towards the prechamber, such a crack is easy to see, but how to see it if it forms under the prechamber and does not come out?

—under the valve guide- another hot spot where no cracks are visible, firstly, it is already dark in the channel, and secondly, the crack is covered with a guide sleeve.This requires a different approach, not just a visual one. And what is the use of detecting a crack between the valves if gases do not burst through it? We will not rely on chance, especially since the diagnostic method was invented a long time ago and has proven itself from the best side.

To check the cylinder head for cracks, it must be pressurized, that is, all holes must be tightly closed, and air must be blown into the channels. If you put the head in water, then bubbles will come out of the crack. Or vice versa, plug all the holes and pour water into the channel, then pump air there with a pump, creating a pressure of 0.6-0.7 MPa, and let the head stand like this for 1 = 2 hours. If the water goes away, then the head is broken.

And the holes in the cooling jacket are closed very easily: a rubber gasket is placed on the nick, which is slightly larger than the hole, a metal plate is applied on top, which is screwed to the head with a bolt. And no water will pass like this. And a pump is connected to the fitting, which will protrude from the head, and air is pumped. This pressure test reveals all cracks.The crack can only be properly repaired by welding. No adhesive will be able to properly seal the crack in the head, because when heated to operating temperatures, the head will expand and the crack will become larger, that is, a composition is needed to seal the crack, which would have the same linear thermal expansion as the material of the head, to besides, be resistant to other loads. All this can only be achieved by welding. Image - DIY cylinder head crack repair

Before welding, the crack must be cut; for this, the metal is drilled out with a milling machine along the entire length of the crack. The groove should be deep enough, 6-8 mm in depth and approximately the same in width, it is desirable to make it wedge-shaped in shape. This will help the metal weld better. To cut the cracks between the saddles, you first need to remove the saddles, and only then cut the crack.

After cutting the cracks, the head must be heated to a temperature of 200-250 ° C, but not higher, so that the head does not move. Heating helps to reduce the stresses in the metal that occur during welding. It is best to use an acetylene torch or oven for heating, but you cannot use a blowtorch, because it can easily overheat the cylinder head.

Gas welding with filler material can be used to weld the cylinder head, but argon arc (TIG) welding gives the best results. A mass is connected to the head, and the arc burns in an argon atmosphere between the tungsten electrode and the head, where an aluminum filler wire is inserted.

After welding, the seam must be cleaned, re-pressed, and if everything is fine, then the surface adjacent to the block must be milled so that it is perfectly flat.

Often there are engine breakdowns that pose a difficult question for car owners: buy another one or try to repair this one? If you decide to buy a new motor, then you will need to find money for it, look for the necessary model in the sale. If a decision is made to repair, then another question arises: how reliable will the result of the repair be?

Some of the most unpleasant breakages are cracks or holes. Using the products and original technology of the Seal-Lock company, high-quality and effective repair of cracks and holes in the engine housing is carried out. This method has advantages over widespread restoration methods such as welding and the use of adhesives. The technology does not require heating cast-iron or silumin parts, which means that there will be no residual stresses in the seam zone, leading to the appearance of new cracks. In addition, it provides a durable seal.