DIY cylinder head crack repair

In detail: DIY repair of a cylinder head crack 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 contact a professional service, for example, OEM-Service, for help in time. 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 treated 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.

Most often, cracks in the cylinder head appear as a result of mechanical damage, overheating or due to freezing of the coolant in the cooling system.

A gradual decrease in the level of coolant (coolant) in the system;
Bubbles in the coolant expansion tank;
Oil in antifreeze or vice versa;
The appearance of an airlock;
Constant problems with the coolant temperature (sometimes too high, then vice versa).

Despite the above signs, finding the crack itself can be quite difficult, and sometimes even impossible. Even an experienced "minder" can search for a crack formation site for a very long time. The thing is that cracks appear in different places on different motors.

Between the valves. As a rule, the crack is immediately visible, it passes under the seats of two adjacent valves.
Between valve and spark plug. The situation is similar, and the crack itself is visible immediately, you don't have to look for it.
On diesel engines, a crack can easily form at the valve location and move towards the prechamber. Again, finding this crack will not take much time and effort. However, if crack in the cylinder head formed under the prechamber, it is unlikely to be seen.
Under the valve guide. This place is also one of the most unpleasant from the point of view of detection. The first is that the channel is dark enough, the second is that the crack is covered with a guide sleeve. In such a situation, a special approach and diagnostics are required.

Now I propose to go directly to the list of ways to solve this problem.

Gas or electric welding

600-650 ° C). Then, using a flux, a neat, even seam is applied to the cast-iron-copper filler rod and the neutral flame of gas welding. The seam itself should protrude above the surface, but no more than 1.0-1.5 mm. Upon completion of all welding work, the unit is slowly cooled in a heating cabinet.

Also, sometimes welding is performed without preheating the block, but in this case, electric welding with direct current of reverse polarity is used. If a crack requires it, a mild steel patch is allowed, for this, electric welding and copper electrodes wrapped in tin are used. After that, the welds are processed and covered with epoxy paste.

Installation of pins... Holes Ø 4-5 mm are drilled along the edges of the crack. After that, with the same drill, it is necessary to drill holes along the entire length, the distance between the holes is 7-8 mm. A thread is cut in the holes, then copper rods are screwed into the holes to the thickness of the wall. After that, the rods are cut with a hacksaw, but not completely, it is necessary to leave the tips about 1.5-2 mm above the surface. Then, between the installed pins, additional holes are drilled so that they can overlap the previous ones. When all the rods form a continuous strip, the tips are flattened with a hammer, thereby rasping the surface of the pins and forming a continuous copper seam. For reliability, the surface is coated with epoxy paste or resin. After completion of the repair work, the block or head is compulsorily pressurized.

Read also: DIY aluminum blinds repair

All of the above work should be performed by specialists or people who understand the complexity of the process and know how to handle certain materials.

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, cracks can be repaired by hand.

One of the most widely used methods of eliminating cracks in the cylinder block and cylinder head is to seal the defects of 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 an angle of 90 degrees. 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.

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 such a 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 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!

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, a 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, 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 heads, 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 repair of a cylinder head crack

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.

Over time, many car units wear out, fail, or, even worse, break down. Today we will tell you how to independently eliminate cracks formed in the head and engine block.

All cracks are subject to resuscitation, with the exception of those that pass through the valve seats, cylinder mirrors, as well as the contact plane of the block and head. In the latter case, the product is rejected, in the rest they are trying to rehabilitate them, this is what we are with you, dear readers, and we will do.

At the very beginning, it is worth reporting that there are several ways to eliminate defects. Briefly about all.

The first method includes sealing cracks using a conventional drill or electric welding.

If the block is cast iron, then the ends of the crack can be drilled with a drill and grinded at an angle of 90 along the entire length with a circle, chisel or some other device.

If you have chosen to eliminate cracks using electric welding, then before starting work, the block must be warmed up to 600-650C. Then, using a cast iron - copper filler rod with a diameter of 5 mm and a flux, you need to apply a continuous even layer, which should not stick out more than a couple of millimeters above the metal surface. After the crack has been welded, the block should be slowly cooled in an oven.

The above method is not the only one, you can weld a crack without heating the block, but for this you need electric welding.

You can also weld on a patch, for this you need tin-wrapped copper electrodes. Finally, the seams must be covered with epoxy paste.The epoxy paste that we have already mentioned can be used to repair cracks in the head and engine block in another way. To do this, it is necessary to clean their surface, drill small holes at the ends of the crack, then cut a thread into them and screw in flush plugs made of copper or aluminum. Then it is necessary to degrease the surface (acetone or gasoline is suitable for this). Then, using a spatula, you need to apply layer by layer, as a result, you should get a layer 3-4 millimeters thick. After that, the epoxy should harden within a day, and if you create a centigrade heat, it will harden in a couple of hours. Finally, sand the surface and you're done!

For the third method of eliminating cracks, we again need epoxy paste and fiberglass, which we will use as a patch. The preparatory stage for work is similar to that presented above, only each layer of paste must be alternated with fiberglass. Do not regret making the patch with a margin of a few millimeters, otherwise the result will be unsatisfactory. The last coat must be epoxy.

And the final option for today, but not the last in the general list, is the option of reanimating cracks in the block and the engine head - with the help of pins. To do this, at the very beginning, along the entire crack, we drill holes at a distance of 7-8 mm from each other. We cut the threads and screw in the copper rods to a depth corresponding to the wall thickness. Then we cut them off with a hacksaw, leaving the ends protruding above the surface of the part by a few millimeters. After light blows, rake out the ends of the pins, which form a continuous seam. To consolidate the result, in the end, you can cover it all with epoxy.

We have described the most suitable options for self-repairing cracks in the head and engine block, however, unfortunately, the troubles with the car do not end there, problems can still arise when the camshaft is worn out, as well as when the shock absorbers are worked out. In any case, do not despair, all this can be easily eliminated with your own hands, only by following our simple recommendations.

Regardless of which metal alloy is used in the manufacture of the block, over time during operation, a crack can form in the engine block. Visually it is possible to identify deep breaks, but microcracks cannot be identified "by eye". Image - DIY repair of a cylinder head crack

The following are the signs by which you can indirectly determine a crack in a block or head. Although, the described symptoms may indicate other malfunctions.

It is better to use imported and silicate-free G-11 antifreeze for aluminum blocks. For cast iron cylinder blocks, it is better to use standard red antifreeze. It is designed for a temperature of -80 +135.

To finally make sure that microcracks are formed, there are several ways to identify defects.

The magnets are installed on the body of the device or the cylinder head. Metal shavings are poured on top. It begins to move to the places where the magnets are installed, hammering into cracks.
On the cylinder head surface thoroughly washed with acetone or kerosene, apply a special liquid paint and wait 10 minutes. After that, wipe off the remaining paint with a clean rag. Defects after such a method are detected immediately.
Liquid can be used to check the integrity. To do this, it is necessary to tightly close all openings and pour water into the channel. Using a pump, we pump air into the channel at a pressure of 0.7 MPa. We leave the block in this state for several hours. Leaving water will indicate that there are defects in the block head.In the same way, the integrity is checked by immersing the unit in a container of water. In this case, bubbles will show where the cracks are.

Locations of defects, for the elimination of which it is not worth undertaking.

on valve seats;

on the cylinder mirrors;

on the plane of contact between the block and the head.

Drill the cracks with a drill so that they do not go further and do not begin to grow during operation. Grind. Image - DIY repair of a cylinder head crack

We heat the block up to 600-650 degrees. For sealing, we use a filler rod made of a cast-iron-copper alloy with a diameter of 5 mm and a flux. Protect the seam from oxidation with borax.

An even layer with a protrusion of no more than 2 mm should remain on the surface in the engine block. After that, we cool the unit in a heating cabinet.

In this case, heating of the block is not required. Electronic wire is used as filler material. Argon is used as a welding medium. Do not overheat over 60 degrees.

We heat the head to a temperature of 200 degrees. We use an acetylene torch for this. The sealing is done using direct current. The diameter of the electrode is selected depending on the width and thickness of the wall.

We select a piece of metal the size of a crack. We wrap the copper alloy electrodes with a tin can and weld the patch. Sand and finish with epoxy paste.

Cut the fracture by grinding and drill the ends of the cracks with a drill, no more than 85 mm in diameter. Insert copper plugs into the holes. We traverse the outlines of the cracks with a notch to create an artificial roughness.

We degrease the surface using acetone, heat it with an infrared lamp to a temperature of 80 degrees. Apply epoxy paste to the fault in the following sequence:

1 layer 1 mm,
second 2-3 mm,
the third is 3-4 mm.

Withstand for 24 hours at a temperature of 20 degrees, then it is necessary to dry the repair site in a drying chamber, at a temperature of 90 degrees, for one hour.

After drying, clean the bonded area and level with sanding.An experienced motorist knows that the performance of a car depends on the performance of the engine. And one of the main components of the motor is the head. How to check the cylinder head for microcracks and what are the signs of head cracks? You can learn more about this here.In most cases, motor wear occurs in the upper part, that is, on the head. There are many reasons that affect the failure of the unit. Overheating of the motor is common when antifreeze completely flows out of the cooling system. This occurs as a result of incorrect tightening of the cylinder head pins. This and the incorrect operation of the temperature control device can cause deformation of the cylinder head plane. Image - DIY repair of a cylinder head crack

An arrow marks a surface defect

Consider the signs and symptoms that indicate the appearance of cracks on the cylinder head and the need to repair the unit:

The motor fluid foams and bubbles appear in it. If the head is cracked, coolant can enter the oil. In this case, antifreeze will leave the expansion tank for an unknown reason. If you need to constantly add refrigerant to the system, this should alert the owner of the car. In this case, an oil film will form in the antifreeze expansion tank - this is an exact symptom of the appearance of microcracks in the engine head.
With such a malfunction, in warm weather, the temperature of the motor will either drop or rise. This sign is not common, but if you notice that the arrow on the temperature sensor goes down and up again, then this should alert.
Engine troika. The internal combustion engine vibrates very much, especially when driving uphill. This symptom is a consequence of the formation of microcracks. If antifreeze gets into it, and the oil is not foamy, then there is another way to calculate the malfunction. To do this, you need to dismantle the candle and look at it: if there is liquid on the candle, then wipe it off with your finger and put it on your tongue.Any antifreeze has a sweetish taste. If so, then a crack has formed on the block head of your car.

Cylinder head defect

The engine fluid leaves, it must be constantly refilled. In this case, it will not work to calculate the crack using antifreeze. If a gap appears next to the intake valve guide, oil will be drawn into the cylinder when the engine is running.
If coolant gets into the intake valve, then during a long drive it will literally wash the pistons to perfect cleanliness. It is easy to check this: unscrew the candles and look at the condition of the pistons.

Boiling coolant. Notice that the antifreeze is constantly boiling, open the hood and the expansion tank cap. Add as much fluid as needed and start the engine. If the antifreeze immediately starts to boil, then there should be no doubt about the malfunction.

To make repairs and eliminate microcracks, you need to be completely sure that they are. Let's consider several diagnostic options that can be done at home.

The method is the most efficient type of repair in detecting microcracks. This is as follows: install magnets on all sides of the cylinder head. Sprinkle the cylinder head with metal shavings on top, it will begin to move towards the magnets, remaining on the cracks and dents. So, it will not be difficult to notice the cracks.

Metal shavings for diagnostics

To check the cylinder head for defects with this method, you will need a special coloring fluid.

Thoroughly rinse the surface of the head, for this use acetone, kerosene or another type of solvent.
Apply a special liquid to the cleaned surface and wait a few minutes.
Then rinse off the remaining liquid with a clean cloth. If there are defects on the cylinder head, then they will be visible to the naked eye.

The method can be implemented in several ways: with and without immersion of the cylinder head under water. Do the immersion test:

If you decide to make diagnostics with immersion of the cylinder head in water, then you need to tightly close all the channels of the circuit of the upper part of the unit, then place it in a container and pour hot water there.
Then supply compressed air to the cylinder head circuit and where bubbles appear, there will be microcracks.

Pressure diagnostic equipment

The method without immersing the unit in water is carried out to search for holes in punctured tires:

it is necessary to firmly close all channels of the cylinder head circuit.
After that, soap solution should be poured onto the surface of the head cover.
Air must be supplied to the circuit. Where a defect is found on the surface of the head, soap bubbles will appear.

The method does not differ from the previous one. The only difference is that the head does not need to be immersed in water, but water should be poured into it:

Close all openings tightly.
Pour more water into the canal.
Then, using a conventional pump, you need to pump air into the channel to make the pressure at least 0.7 MPa.
After that, it is necessary to let the head stand for several hours. If the water is gone, this indicates a defect in the head. This means that you cannot do without repairs.

Argon surface welding

It is advisable to repair block cracks by welding, this method is the most effective and reliable.

Before starting the repair, you need to cut out a piece of metal that matches the crack in size. The depth of the groove must be at least 8 mm and the shape must be wedge-shaped.
Before brewing the head, it must be heated to a temperature of 200 degrees. An acetylene torch can be used for this, but not a soldering iron.

Video (click to play).

Welding head cracks

For repairs, use a gas installation with additives. Effective results are obtained with argon arc welding. You need to connect the mass to the cylinder head. The arc should burn between the head and the electrode, and a piece of metal should be placed there, which will be sealed with a crack.

When the welding is completed, we carefully clean the seam and press it again. If there are no defects, then the surface of the head must be milled.