How to check valve tightness? We fix valve leaks with our own hands!

Checking the tightness of the valves is an important undertaking, since the correct operation of the power unit largely depends on the tightness of the intake and exhaust valves to the seats. Today you will learn how to check the tightness of valves, as well as how to grind valves at home using special probes and a set of accessories. Without the correct and coordinated operation of the timing mechanism (gas distribution mechanism), uninterrupted operation of the engine is impossible; this must be understood and all existing problems in the operation of this system must be identified in a timely manner. The key role in the timing is played by the intake and exhaust valves, as is already clear from the name, some release and others let in... The tightness of the valves is an important point, on which, as mentioned above, a lot depends, otherwise there will be no combustion in the combustion chamber the necessary pressure will be created and the operation of the internal combustion engine will be ineffective, and possibly even impossible.

In order to check the tightness of the valves you must have:

Set of flat probes;
A wide bench ruler or a special template;
Lapping paste;
Kerosene;
A special “device” for grinding in valves.

What is EGR

USR sensors can be found in almost any modern car - this is a small device that performs a number of tasks related to reducing toxicity. The EGR valve has a simple and reliable design. The main task performed by EGR is to reduce the level of nitrogen oxide contained in exhaust gases. It is installed on both diesel and gasoline cars, except for vehicles with turbocharged engines (although there are exceptions here too).

Reducing the formation of nitrogen oxide (N2O3) is achieved by diverting part of the exhaust gases back into the combustion chamber. This happens because the exhaust recirculation valve maintains the throttle valve in the open position due to the pressure created by the gases returning to the engine. This leads to a decrease in cylinder temperatures, the exhaust becomes less toxic, fuel consumption is reduced and detonation is reduced due to a change in the ignition timing.

This achieves two goals:

displace some of the excess air;
absorb excess thermal energy inside the cylinders.

Thanks to this, the emission of nitrogen oxides, which is one of the most toxic substances present in exhaust gases, is reduced. It is formed under the influence of high temperatures and endothermic reactions of oxygen with nitrogen.

Considering all the factors, we can say that EGR is a mechanism that contributes to the following:

reduces harm to the environment;
reduces fuel consumption;
retains engine power.

It is also worth noting that recirculation is only possible in partial load mode. The first USR systems were pneumatic and complied with the environmental standards EURO-2 and EURO-3. Tighter regulations have led to almost all of them becoming electronic.

Is it possible to drive with a broken gasket?

A broken cylinder head gasket causes the following problems:

engine overheating;
decrease in oil pressure when antifreeze gets into it;
lack of necessary lubrication of the piston group;
violation of the tightness of cooling, exhaust, compression systems.

With such malfunctions, operation of the vehicle is prohibited, even for a short time. After these symptoms appear, the engine must be turned off immediately and the car taken to a specialized service center.

How the device works

The EGR sensor is controlled using vacuum. The EGR valve connects the intake and exhaust manifolds, and it opens under the influence of the vacuum zone. In order for the engine to operate stably at idle, the recirculation valve is disabled by the ECU.

The valve exhaust is adjusted so that they remain open for some time at the beginning of the stroke. Thus, part of the exhaust gases returns to the combustion chamber.

USR diesel engine

It's also worth noting that this is not the only system for reusing exhaust gases. An internal system is found on some car brands. It does not provide for the use of additional equipment, since it is built into the design of the engine itself.

When using additional cooling devices, the list of things that are affected by EGR expands. The operation of such units is to cool gases using antifreeze. This has a significant impact on the combustion temperature, leading to a reduction in the amount of nitrogen oxide produced.

Valve disc grinding machine — logbook Ford Sierra 1984 on DRIVE2

I don’t trust anyone, so I decided to edit the valve plates myself.

I bought a suitable bracket and bearings from the store. A start.

At the market I bought a motor from a Soviet video recorder to drive the valve rotation.

I attached the motor to the back. I used a piece of inner tube from a bicycle as a belt.

The belt presses the valve well against the rollers.

Test of valve rotation from the built-in motor -

Using a metal plate, I built a valve movement limiter.

Using another metal plate, I pressed the valve from above.

Now the valve has nowhere to go. Just rotate.

I organized the valve grinding itself in two ways.

The first method is a drill with a grinding attachment. The advantage is adjustable rotation speed. Since the revolutions of the drill almost completely coincide with the revolutions of the valve drive motor, I chose this option as the final one.

The second option is an electric sharpener. The advantage is noiselessness, the ability to spin it from a rotating valve without connecting to a 220 V network.

The electric sharpener was specially tilted slightly in order to grind at a slight angle to the plane of rotation of the valve.

Here is the result. There is no longer a deep groove.

View of the valve after finer grinding.

The grinding works well.

And this is an experimental valve with a large chamfer roughness after grinding.

Exhaust gas recirculation sensor in a microprocessor system

In principle, the EGR system consists of a poppet valve with a special valve. The device performs only two functions - it releases or prevents exhaust gas from getting back into the intake tract area of the power plant.

In microprocessor-based (electronic) engine control systems, the EGR valve operates not at the moment of vacuum in the intake manifold. For this purpose, electric or electro-pneumatic methods are used to move the valve through a servo drive. The operation of the USR is controlled through the ECU, which calculates the required amount of exhaust gases for recirculation, and then sends a command to open or close the valve.

The functionality of the EGR is greatly influenced by various sensors (for example, oxygen). Using signals from these devices, the electronic control unit carries out the necessary calculations and issues commands to open or close the valve.

Advantages of solenoid valves for water

The main advantage of the device is the ability to remotely and quickly regulate the flow of the working environment. Without electromagnetic shutters, the operation of complex technological installations and simple household appliances, such as a coffee maker and washing machine, becomes impossible.

In addition, the electric drive allows:

Connect the solenoid valve to a centralized and automated control system. This greatly increases the accuracy and efficiency of parameter adjustments compared to manual control.
Reduce labor costs for managing technological processes.
Increase production safety and eliminate the operator’s exposure to harmful factors in the production environment.
Increase the efficiency of household appliances and production plants through precise and fast control of the flow of working media and their parameters.

An important advantage of a solenoid drive compared to an electric motor and gearbox is the absence of gears and worm gears, exceptional simplicity of the device and a minimum of moving parts.

This ensures high equipment reliability, minimal wear and a long service life.

The disadvantage of this type of device is the inability to smoothly adjust the degree of shutter opening. Only two positions are provided: “open” and “closed”.

Symptoms of EGR malfunction

There are a huge number of signs that indicate a defect in the operation of the entire EGR system and its sensor, in particular. However, these symptoms can be caused by disturbances in the operation of other elements and components of the power plant, therefore, if they are identified, additional diagnostics must be carried out.

The main signs of problems with the exhaust gas recirculation valve include the following:

A drop in the power of the power plant and a deterioration in the dynamic characteristics of the car. In other words, the car accelerates hard at the start and drives poorly when loaded while driving uphill.
Unstable engine operation, especially at idle. When idling, the engine may simply stall.
The power plant stalls immediately after starting. May occur due to the EGR valve being stuck in the open position. As a result, exhaust gases freely enter the intake manifold.
Increased fuel consumption. Due to the vacuum in the intake, the fuel mixture begins to become over-enriched with fuel.
Errors appear on the car dashboard. More often, the “Check Engine” signal comes on, and after diagnostic measures, defects are identified that are caused by incorrect operation of the EGR. This includes errors p0404, p0401, p1406, etc.

If any of the above symptoms are detected, it is recommended to diagnose the car using a special scanning device. Thanks to it, you can make sure that the defects are in the EGR valve. Scan Tool Pro Black Edition is perfect for these purposes; it perfectly reads errors, displays readings from different sensors in real time and corrects individual parameters.

The device is used by many auto repair shops, but if desired, it can also be purchased for personal use. It is compatible with the protocols of domestic, Asian, European and American cars. By connecting it to a mobile device using Bluetooth or Wi-Fi with special software, you will get access to information about the power plant, gearbox, transmission, and all auxiliary systems ABS, ESP, etc.

Lapping process

The valve is dried out and removed, after which a thin layer of lapping paste is applied to the edge of its plate, where it rests on the seat. The valve treated in this way is inserted into the guide and completely recessed into the seat.

On the reverse side, its shank is clamped with a fixing device or tube and the grinding process begins. To do this, it turns approximately half a turn, then rises up, with a slight effort lowers itself into the saddle again, while a light slap should be heard, and turns half a turn in the opposite direction. This process lasts about 2 minutes, after which you need to check the grinding. It should be noted that the paste has a specially selected consistency, which ideally manifests itself when the surface is processed for at least 2 minutes; its elements are broken, providing a higher quality of grinding.

Checking the degree of lapping is quite simple. First, the device holding the valve shank is removed, it is removed, washed and carefully inspected. The chamfered plate should not have any visible flaws - scratches or shells. If such damage is visible, the operation must be repeated until a smooth, smooth surface appears.

After a visual inspection, a leak test must be performed. To do this, the valve is thoroughly washed with gasoline, and the seat is washed in the same way so that the plate can be seated in it as tightly as possible. Next, liquid is again poured into the exhaust well; a properly lapped valve will not let it through, no streaks will appear on the surface, it must remain completely dry for at least 2 minutes.

When working with a rubber tube, the process is carried out in the same way, but this makes it difficult for the valve to slam against the seat, so grinding is done with rotational movements while tensioning the tube. More experienced car enthusiasts may be advised to connect the end of the tube to a drill and turn the valve in the seat at reduced speed. In this case, every 10 seconds you need to turn on the reverse so that the production of metal on the plate occurs evenly.

If the seat is damaged, its restoration requires a special tool - cutters. It is made according to its shape and is put on a drill, with the help of which the entire area is processed. This work requires certain qualifications, and destruction of the seat surface most often occurs when the valve burns out, which is better not to let this happen.

Video: how to grind a valve and check the quality of grinding

Conclusion

To grind the valve head, an experienced car enthusiast will not have to go to a specialized service station. When working, you will need a simple device with which the valve shank is securely clamped. This allows you to simultaneously lap and tap it to the saddle, which increases the efficiency of the procedure. You need to know that the lapping procedure will be required when installing a new part and when overhauling the engine.

Correctly carried out lapping will increase the dynamic characteristics of the engine, save fuel, while hot gases will not damage the valve system and the engine will last much longer.

Seal

Causes of EGR system malfunction

There are only two reasons why the EGR valve fails. The first is that an insufficient amount of exhaust gases is supplied through it. The second is that an excessively large flow of exhaust gases passes through the valve. But the following problems can serve as a sign of one or another defect:

Carbon deposits have formed on the EGR valve stem. May occur as a result of natural causes. Since a large amount of exhaust gases passes through it, soot can settle on the walls and rod. Especially when the car is operated in aggressive conditions - the engine is worn out, the amount of crankcase gases is increased, low-quality fuel is poured, etc. Upon completion of the diagnosis, you should always clean the stem with carbocleaner or a similar degreasing cleaning composition. More often, various types of solvents or acetone are used for these purposes; pure gasoline and diesel fuel are also suitable.
EGR valve membrane leakage. As a result, the system cannot be closed or opened completely, and, accordingly, exhaust gases constantly pass through it.
Coked EGR channels. Leads to obstruction of exhaust and air passage. It appears due to the deposition of carbon deposits on the walls of the valve and the channels through which gases pass.
Incorrectly muted EGR system. Many car enthusiasts, faced with a loss of engine power due to defects in the system, turn off its valve. But after making such a decision, the plug must be installed correctly, otherwise the air flow sensor will record excessive air consumption. Owners of used cars especially often encounter this; in this case, the new owner may not even know that the EGR valve on the car is plugged. If the vehicle model is equipped with such a system, then be sure to ask its former owner about the condition of the unit and find out whether it is muffled or not.
The EGR valve gets stuck when closing and/or opening. This can happen for two reasons. The first is that the sensor itself has failed and therefore does not transmit correct data to the ECU. The second is a defect in the valve. It may not open completely or partially close. More often it occurs due to a large amount of carbon deposits on the mechanisms, which was formed as a result of fuel combustion.
The EGR valve moves jerkily. If the solenoid is working properly, the rod moves smoothly, and the sensor records a gradual change in the position of the damper. In case of jerky movement, incorrect information is transmitted to the electronic control unit, which leads to the consequences described above.

Coked Opel USR system
On car models in which the valve movement is provided by a stepper electric drive, the cause of the breakdown may lie in it. In this case, the electric motor or drive gear may break.

Why are hands bad?

The disadvantage of such processing is quality, which significantly affects reliability. Usually, after this type of treatment, the engine travels 10-20,000 km, and then it needs to be repaired again. But even during this mileage the engine will operate unstably; gas breakthrough is inevitable. This is due to the fact that it is impossible to correctly center the valve relative to the seat during lapping. Therefore, if you have the opportunity to process a part using professional equipment, you should not look for freebies and do mechanical processing “on your knees”, do not forget - “Krailovo leads to padalovo” (c).

How to check the EGR system

Depending on the make and model of the car, the EGR sensor may be located in different places, but in any case it will be located next to the intake manifold. Sometimes it can be installed on the intake tract or on the throttle body. Self-checking should always begin with a visual inspection.

There are two methods for identifying defects in the operation of the USR - without removing it from the seat and with dismantling the unit. However, more accurate data can only be obtained using the second method. And if carbon deposits and soot are detected on the EGR valve, it can be immediately cleaned and then replaced. Let's start with the method of checking without removal.

Important! After installing a new EGR valve, it will need to be adapted and configured using a special program. Only after this will it work normally in conjunction with the ECU.

How to check if EGR is working properly

First, you should check the EGR valve itself and make sure that it works at all. This is very simple to do - a visual inspection is carried out.

To do this, you need to observe a little the reaction of the rod during gas releases. In this case, you will need an assistant. One watches, the second presses the gas pedal. Or you can try to press on the membrane - in this case the speed should drop.

The solenoid valve is checked by supplying power to the connector contacts directly from the battery. At the moment of connection, characteristic clicks should appear. Once you have verified that the EGR valve is working properly, you can begin to carry out more detailed checks.

Pressing the EGR valve

Start the car, leave it idling and try to press on the membrane. Depending on the make of the car and the year of manufacture of the model, the valve may be located in different places. So, the Daewoo Lanos, which is very common on our roads, needs to be pressed under the plate. It has a special cutout in the body through which you can get to the membrane. As a result, you do not press on the membrane itself, since it is located under the body, but on the part of the structure under which it is located.

While pressing, the speed should drop and the engine should “suffocate”. This indicates normal operation of the assembly and indicates good condition of the valve seat. In this case, there is no particular need to repair anything, except perhaps dismantle, clean and carry out diagnostics after installation as preventive measures.

But if nothing happens when you press and the motor continues to operate at the same speed, then you can judge that the unit is depressurized. This means that the EGR membrane is leaking gases and the system does not work. Therefore, it is necessary to remove it from its seat and carry out additional diagnostics of the USR valve and other elements of the assembly.

Checking the EGR valve

As already mentioned, the valve may be located in different places on different vehicles. More often it is mounted next to the intake manifold. In the Ford Escape 3.0 V6, it is embedded in a metal tube that comes from the intake. The valve opens due to the formation of vacuum coming from the solenoid.

To check the correct functioning of the USR system, the engine must be started and left to idle. Then disconnect the vacuum hose (through which the vacuum is transmitted). If you have a vacuum pump at hand, then it is connected to the valve inlet and a vacuum zone is created. If the unit is working properly, the car will “chop” and jerk, at which point the speed will begin to drop. If there is no pump at hand, connect a regular hose of a suitable diameter and simply extract the air. The same thing should happen as in the case of the pump.

If the car continues to operate without interruptions and the number of revolutions has not changed, most likely the valve is damaged. It needs to be removed and further diagnostics carried out. For repairs, it will still need to be dismantled, and the work is carried out in a car repair shop or garage.

Solenoid check

A solenoid is an inductor through which electric current is passed. It changes the voltage passing through it, thanks to pulse width modulation or PWM. This is the signal to supply vacuum to the EGR valve.

The first step in diagnostics is to check the presence of vacuum and how strong the vacuum is. To do this, all the small tubes under the solenoid are disconnected, and then the engine is started.

Important! Disconnect all elements very carefully so as not to break the fitting on which they are attached.

If the vacuum created is sufficient, it will be audible. You can put your finger on the edge of the tube. If it is absent, further diagnostics will be required. The EGR valve is also carefully removed from its seat for further inspection.

Then the electrical part is checked, or more precisely, the power supply to the solenoid. To do this, you need to disconnect the connector from the element being tested. On it you will find three contacts - signal, power and ground. Using a multimeter in voltage test mode or a voltmeter, the power is checked. The red probe is applied to the power wire, the black one to ground. If there is power, the multimeter display will show a value of 12 V.

You can also check the pulse wire for integrity. To do this, you will need a multimeter in resistance measurement mode or an ohmmeter. The wire we need is often colored purple, and when connected to the computer, it has the number 47. Upon visual inspection, all conductors should not have kinks or damage to the insulation. If the wire is broken, it must be replaced with a new one. If the insulating layer is damaged, you can try to restore it using electrical tape or heat shrink. This can only be done in case of minor insulation violations.

Then the wires on the solenoid itself are checked. The multimeter is switched to resistance measurement mode or an ohmmeter is used. The probes of the device are connected to each of the two terminals of the solenoid. The resistance value on different devices may differ, but in any case it should not be near zero (this may indicate that the coil is shorted) or tend to infinity (indicate an open circuit).

Checking the USR sensor

The main task of the EGR sensor is to record the difference between the pressure in two different parts of the valve and transmit the resulting data to the vehicle's electronic control unit. And the ECU sends a signal to open or close the USR valve.

First you need to check the power to the sensor. The multimeter is switched to the DC voltage measurement mode at a value of 20 V. The red probe is applied to wire No. 3, and the black one to ground. After this, the car engine starts. If the sensor is working properly, the multimeter display will show a value of 5 V.

Then the presence of voltage on impulse wire No. 1 is checked. Under normal conditions and a non-overheated engine (USR system is disabled), the indicator should be around 0.9 volts. It is measured in the same way as in the previous version. That is, the red probe is to wire 1, and the black probe is to ground.

If the sensor is working properly, the output voltage on the pulse wire will gradually increase. When it reaches approximately 10 volts, the valve will open. If during testing the voltage does not increase or changes intermittently, then we can judge that the sensor may have failed and additional diagnostics are required.

If the engine stalls shortly after starting, you can try removing the EGR valve, and then leaning and removing it to look at the reaction of the power plant. If, after removing the valve from the crankcase, a lot of smoke comes out and the engine runs more stable, it means the ventilation system or the valve has failed. In this case, additional diagnostics are required.

Tools and materials for lapping

There is specialized equipment for grinding valves, but to do the work yourself, use simple available equipment. One such method is to grind the valve with a drill while the valve is rotated in the seat using this tool. The advantage of this method is that it saves time, but it requires skill and is not suitable for car enthusiasts who do not have sufficient experience.

For manual grinding, use a regular thick-walled rubber tube, which fits tightly onto the bottom of the valve. For example, with a valve shank diameter of 7 mm, it is recommended to take a tube with a diameter of 6 mm. This will allow you to hold it tightly while doing work.

A more reliable method is a special device that heals the valve stem by tightening the nut. In this case, it will hold well and not slip, and the grinding process will speed up. It is important to know that using hand tools will avoid damaging the engine valve system.

The main material used in the work is lapping paste, which is applied to the edge of the valve disc. It is a plastic composition with fine diamond abrasive. During operation, it removes thin layers of metal, ensuring tight installation in the seat.

Check with removal

It is more convenient to diagnose the EGR valve after removing it. This way you can more accurately assess their condition visually and using special devices.

Clogged USR channels Opel

The first step is to check its performance. The valve design contains a solenoid, which is supplied with a constant voltage of 12 V, as in the main electrical network of the car.

It is worth remembering that the design of the valve may differ, and, therefore, the numbers of contacts to which voltage is supplied will be different. That is, there is no universal solution here. So the Volkswagen Golf valve has three outputs, numbered 2, 4 and 6. Voltage is supplied to terminals 2 and 6.

When checking, it is desirable to have a constant voltage source, since in a car it is constantly changing. Under normal conditions, a fully operational USR valve opens when the voltage reaches 10 volts on the impulse wire. If the 12V supply is interrupted, the rod will fall and close the valve.

You also need to check the resistance on the sensor. A multimeter in ohmmeter mode is suitable for these purposes. On a fully functional sensor with the valve open, the value at pins 2 and 6 should be about 4 kOhm, and between 4 and 6 about 1.7 kOhm. With the closed position on pins 2 and 6, the multimeter will show a value of 1.4 kOhm, and between 4 and 6 it should be 3.2 kOhm. Naturally, the values may differ on different cars. You need to look at the technical data sheet for exact data.

When diagnosing the performance of the solenoid, you should check the condition of the valve. As already mentioned, a coating of soot may form on it, which settles on the walls and rod of the device. This leads to jerks in the operation of the valve and malfunctions in the functioning of the entire system. Even if there is a small amount of dirt, as a preventive measure, it is recommended to remove it with a cleaner both on the outside and inside.

Valve chamfer grinding machine PT 823

Attached images

I had one like this. Clamp the valve with a collet of suitable rod diameter. I didn't notice the beating. The disadvantage of this machine is that the valve chamfers are burned due to the lack of water cooling. But once you get used to working on this machine, you can get simply excellent results. An indispensable item when repairing valves.

I had one without a cabinet, I don’t know what was there. No spare parts are required for it except standard grinding stones; check the completeness of the collets of the main sizes. There were about 10 different ones in a set. Specific collets may cause problems with the manufacture of new ones. It’s better to take the cabinet away because placing it on the table is inconvenient and takes up a lot of space. Inside the machine, check whether the drive to the collet chuck spindle is working and that the drive belt is intact.