How to check the intake manifold for air leaks. Air leaks through the throttle valve, what should I do? Typical air leaks

Any engine internal combustion must work on a mixture of air and fuel, which are tightly regulated by electronics, if it is an injection engine, or mechanics, if it is a carburetor engine. Any imbalance in the proportion of air and fuel leads to incorrect engine operation, a drop in power, and an increase in fuel consumption. Intake manifold air leaks can severely affect engine stability. How to check and determine the malfunction, identify the main symptoms of suction, let's figure it out right now.

Manifold Air Leakage Symptoms: Check and Identify

Clear signs of a cracked hose

Any unauthorized penetration of excess air into the power system leads to a depletion of the working mixture. The optimal balance of fuel and air is violated, as a result of which the engine pounds, idle speed can disappear altogether, while at speeds above 2-3 thousand the engine can work quite tolerably.

Error P0300

Besides the electronic unit engine control may show a number of errors - P0171, lean mixture, an error may appear P300, talking about misfires in the combustion chamber. Several other errors may occur depending on the engine model.

Nevertheless, the main symptoms of air leakage in the intake manifold are:

unstable idle speed, engine shakes, idle cannot be adjusted;
the engine may stall in transient operating modes;
dips during acceleration;
high fuel consumption;
difficult start at any air temperature;
drop in power, especially at speeds below 2-3 thousand;
the engine is troit, one or more cylinders do not work in certain modes.

Where can the air be sucked in?

One of these symptoms is enough to talk about air leakage in the intake tract. It can be quite difficult to pinpoint the exact location of the air leak, since the place of attachment and sealing of the intake manifold to the cylinder head is far from the only way to suck in excess oxygen.

Depending on the engine model, there may be several suction points:

Damage or burnout of the gasket the intake manifold is one of the most common places for leaks.
New intake manifold gaskets
Injector seals in injection motors.
Backlash and leaks in the axes of the throttle valves of carburetor engines.
Vacuum brake booster.
Connections and hoses that are fixed to the manifold.
A leaky hose on the manifold caused an air leak
Gaskets of throttle assemblies in injection motors.
Valves of the adsorber, plugs on the manifold, leaks in the sensors.
Idle regulators of questionable quality may be leaking.
Leaky idle speed control
Bushings.

As you can see, troubles can be expected not only from the gasket of the collector or the collector itself, at the same time there are a number of measures that will help to find the place of breakdown and quickly eliminate the malfunction.

Determine the place of air leak

Most effective method determining the place of air leakage - visual.

True, for this you have to either find or assemble the simplest smoke generator. Smoke launched into the intake system will instantly show the place of suction with high accuracy. It is clear that not even every service station has a smoke generator, so the simplest device can be assembled by hand.

Do-it-yourself smoke generator

For this, a blowing air gun, a compressor with a receiver and a pack of cigarettes for smoke will come in handy. The gun is simply connected to an air receiver or compressor, a cigarette is inserted into the nozzle of the gun, a pressure of about 0.5-0.8 atm is injected, and the smoke under pressure enters intake manifold.

Homemade smoke generator

The flaw will become noticeable as soon as the smoke finds a place to exit.

Another way to find the place of "suction"

The second way to determine the place of suction is more time consuming and time consuming. For this it will come in handy flammable liquid(ether, gasoline with high octane number, liquid for quick start of the motor in a can). To check and determine the place of suction, it is enough to start the engine and spray liquid on the manifold interfaces.

Sometimes the suction is clearly audible by the characteristic whistle or hiss, but this does not happen in all cases. Therefore, it is necessary to methodically spray with liquid the place where the intake manifold meets the block head and all the suspicious connections that we have listed above. As soon as the liquid enters the place of breakdown, it will be sucked into the intake tract and the engine speed will increase sharply for a while.

other methods

There are several more methods for detecting suction. They consist in accurate measurement of the vacuum in the section from the throttle valve to the combustion chambers, however, the equipment used to implement this method is not always available, and the accuracy of localizing the depressurization site using this method is minimal.

conclusions

The optimal methods for diagnosing air leakage in the intake manifold on their own are the use of smoke and spraying the manifold, corrugations, throttles with a thin stream of flammable liquid. Successful diagnostics and smooth roads to everyone!

If at hard pressing on the gas pedal, the engine of your car begins to choke or stalls, in many cases this is a sign of a clear air leak. An excessive amount of air is supplied to the power unit, which forms too poor air-fuel mixture... And it does not burn as well as the manufacturer intended. This leads to triplet engine and unstable work on the Idling.

The main signs of air leaks

Most often air leaks car engine manifested by the following symptoms:

Problems with starting after a long stay (for example, in the morning).
Decrease in power. On power units with an air flow meter, idle speed drops, and on motors with a sensor absolute pressure(MAP sensor) rpm, on the contrary, increases (diagnostic, misfire and lean mixture also appear).
Unstable operation at idle - the tachometer needle constantly twitches, and at the "bottom" the engine may stall. In cars with a carburetor engine, the quantity and quality of the mixture is practically impossible to adjust, since the air is supplied in an excess volume.
Increased fuel consumption - to start and continue driving, the driver is forced to maintain high revs without switching to higher speeds.

Typical air leaks

Of course, each case is individual, but suction usually occurs in such places of the engine:

throttle assembly gasket;
connection of the intake manifold with the cylinder head;
vacuum brake booster;
adsorber valve;
a branch pipe connecting the throttle assembly and the air filter housing;
vacuum hoses, their joints and tees;
sealing gum fuel injectors;
idle speed regulator.

In the case of cars equipped with carburetor motors, it is much easier to find the suction. There isn't much electronic devices and sensors, and additional air usually enters the engine through a vacuum brake booster or one of the elements of the carburetor itself.

Air leaks in the carburetor:

gasket (suction is easy to detect by the presence of soot);
choke axles;
mixture quality adjustment screw;
leaky throttle valve connection;
Damage to economizer diaphragm, throttle damper vacuum diaphragm, or starter diaphragm.

Diesel fuel system air leaks

Usually airing the fuel system diesel engine caused by damage at the joints of the pipes connecting fuel tank and filter or filter and fuel pump high pressure.

Air leaks in the damaged fuel system are due to the fact that the pressure when supplying diesel fuel from the tank is below atmospheric. Therefore, it is extremely difficult to identify the place of suction.

On the diesel cars which are produced in last years, air penetration into fuel system occurs more frequently than older diesel engines. The reason lies in the different design of the hoses, the service life of which has been significantly reduced. Previously, these elements were made of brass, and now they are made of plastic. Constant vibrations cause wear on the plastic and rubber seals. Most often, owners of cars with a mileage of about 150-200 thousand kilometers encounter such difficulties, and often the suction manifests itself in winter.

The most popular reasons for suction in such cases:

wear of clamps and hoses;
damage to the fuel filter seal;
damage to the seals of the fuel pump cover or drive shaft;
leaking fuel lines;
damage to the return fuel line;

Important! Usually the problem is caused by wear and tear sealing elements... Airing of the fuel supply system can occur on the supply or return line.

Signs of air leakage on a diesel car

Most often, the engine does not want to start after long periods of inactivity. The driver is forced to turn the key in the ignition lock repeatedly using the starter. This is accompanied by the appearance of smoke from exhaust pipe, which is a sign of normal fuel supply. If the suction is very significant, the engine will not only start poorly in the morning, but also stall while driving.

The reason lies in the fact that the pump cannot operate normally at idle speed, because too much air enters the chamber. On the increased revs The high-pressure fuel pump is even more or less coping. Such symptoms are not always caused by the suction, so we advise you to check the "diagnosis" by installing transparent fuel pipes.

How to find air leaks in the diesel engine fuel system

Air can enter the system through a connection, fuel tank, or pipe. The search is done quite simply - by applying pressure or by elimination. In the first case, it is necessary to apply pressure to the fuel tank, after which you will hear a characteristic hiss at the place of suction, or you will see drops of fuel. The second method is to check the elements of the fuel system one by one, ensuring that fuel is supplied from the tank, not the tank. First, we connect to the fuel pump and move on.

Intake manifold air leaks

If air enters the engine that the air flow meter or MAP sensor cannot "see", the mixture of fuel and air will be too lean. This problem is caused by air leaks in the intake tract.

Main reasons:

overheating of the motor (affects the condition of the gaskets);
external interference;
damage to gaskets as a result of improper use of the carbcliner.

Very often, difficulties can arise if the seal between the intake manifold and the cylinder head is damaged, since it is not easy to visually detect such a leak.

Finding suction in the manifold

On the gasoline engines excess air may end up in the manifold due to depressurization of the air ducts, wear of the sealing rubber of the fuel injectors or damage to the hoses leading to the vacuum brake booster.

In order to find air leaks, different methods are used:

Shut off the air supply. It is necessary to disconnect the pipe from the filter housing and start the engine. After that, cover the branch pipe with your hand - if there is no suction, the engine will stall. If the engine continues to run and you hear hiss, there is definitely a suction.
Pinching the hoses. It is necessary to start the engine and after a certain time try to hear a hiss. If it was not possible to find the place of damage to the tightness, it is necessary in turn to pinch the hoses that are connected to the receiver. If you pinch and release the hose and it affects performance power unit, look for a problem in this zone.
Compressed air. The intake system of the idle engine must be treated with soapy water, then shut off the air supply from the filter and pump air through one of the pipes.
Spraying with a combustible mixture. To find the place where air is sucked into the engine, such means as gasoline, WD-40 or a carburetor cleaner are used. With the help of the selected tool, it is necessary to spray all the joints. When the fluid is in the place of suction, you will notice changes in engine operation (rpm should rise or fall). It is better to use a medical syringe for spraying.

Using this method, check the following places: the nipple between valve cover and the idle speed regulator, the pipe between the mass air flow sensor and the IAC, the connection of the intake manifold and the throttle valve, the connection of the manifold and the cylinder head, injector seals, all hoses in the clamping areas.

Smoke generator. Not all motorists have such a device, and therefore it is usually used in car repair shops. You can buy a ready-made solution or make it yourself (there are enough instructions and videos on the Internet). The bottom line is that you need to ensure the supply of smoke through any hose to the intake manifold. Smoke will seep in problem areas.

The appearance of such a problem for any driver is always unexpected and unpleasant. Immediately before the owner, several questions arise about what happened to the car, where to look for a malfunction, how to fix it. Most drivers will turn to specialists or “experts” for help, although in many cases, troubleshooting can be done on your own.

A little about the signs of a malfunction

The power unit of a car is a complex engineering design. If, after detecting even small deviations in its operation, you should deal with the problem that has arisen and eliminate it. If this is left unattended, one can wait for the emergence of major complications, which will entail not only significant material costs, but also moral costs, a long downtime of the machine.

What happens when air leaks on the VAZ 2112, 2114 or other models? A number of symptoms may indicate the appearance of such a malfunction:

Difficult starting of the engine after a long stay;
Idle engine speed "floats";
Engine power is lost;
Fuel consumption increases.

Floating idle speed can cause the engine to stall. If this happened at an intersection, and besides, the engine does not start well, this is already the creation of a traffic jam, the nervousness of other road users, the prerequisites for creating emergency... If the car is equipped with a power unit with a carburetor, an attempt to adjust the idle speed with the screws for the amount and quality of the fuel mixture will not lead to success.

This is hindered by the air leakage that appears past the idle channels. The loss of power indicators of the motor will become noticeable. The car loses its agility, movement at low speeds has a long period. The movement can only be started at higher rpm. On machines with injection engines that are equipped with sensors that monitor the mass fuel consumption, the appearance of too low idle speed will be noticed. The on-board computer may show a lambda probe failure. A lean fuel mixture will not allow obtaining maximum torque, frequent misfires of the mixture in the cylinders become noticeable. Driving as usual will result in increased consumption fuel.

Advice! If you notice the appearance of these signs, stop the car and carefully inspect the engine compartment. The cause of the failure may be a loose hose clamp, or other similar "trifle".

How to find a problem spot

Sometimes this may take only a few minutes, in other cases, quite a long period. In addition to the manifestation of these signs, the appearance of a malfunction may be indicated by on-board computer signal "lean mixture". It is not as easy to detect air leakage in a VAZ 2112, 2114 power unit as it might seem at first glance. To perform this operation, there are several different ways... This article will look at them in more detail.

The entry of "excess" mixture is possible at the joints and seals in the intake tract of the engine. This fully applies to all hoses, gaskets, injectors, throttle valves, sensors, and other components of the intake manifold. There have been cases when the gasket between the head and the cylinder block became the culprit for this phenomenon. Disconnect the RTM sensor first. Then start the engine and close the inlet with a flat object. The motor must stop, otherwise there is a "hole".

Try to spray on problem areas plain water. It can close the hole that appears for a short time, which will lead to a slight decrease in speed. Instead of water, you can do the same procedure with ether. In this case, the turnover should increase. It is not always possible to find a pass for an excess mixture of a VAZ power unit by such methods, therefore mechanics use other methods. Reputable automotive centers in such cases simply measure the intake manifold vacuum. For this they have special measuring instruments... They are commercially available, but it is not economically feasible to purchase them for a single use.

What should the driver do? Effective help search for places of air leakage VAZ 2112, 2114 provide steam generators, smoke generators. They have simple design and easy to assemble at home. The process of describing their manufacture can be easily found on the Internet, so we will not dwell on this. Let's consider in more detail the issue of their use. Any, even the slightest violation of the tightness, can be detected by the plumes of smoke that forms in the smoke generator.

To quickly find the "hole" you need to correctly connect the outlet of the smoke source to the intake tract. Most suitable place many mechanics consider the place of connection of the hose from vacuum booster brakes. They serve a smoke mixture and try to find leaks in the joints. In most cases, this turns out to be the most effective method.

A few words about troubleshooting

It was possible to find air leakage in the VAZ 2112, 2114 engine, now it should be eliminated. The algorithm for resolving the problem will be different, depending on the place of the pass. If clamps are the culprit, they are tightened. If this cannot be done due to the hardness of the rubber pipes, it is better to replace them with new ones. Leaky gaskets are also replaced with new ones. In some cases, this can be a time consuming process, for example, when replacing the gasket between the head and the cylinder block.

For this, desire alone is not enough, since you will need to use a torque wrench to tighten the block head bolts, a diagram of their installation and screwing. After a short run, they will have to be squeezed again. It will be a little easier to replace the intake tract gasket, but you will also have to dismantle and then reinstall a number of parts.

Advice! If this is the first time such an operation is performed, write down the order in which assemblies and parts are removed. This will make them easier to install during assembly.

Mechanics noted cases when the power units of the VAZ 2112, 2114 had air leaks in the fuel rail. For some reason, VAZ manufacturers install a rubber hose, compressed with two clamps in the fuel supply system. After crimping them again, the problem is usually eliminated. Most often, replacing "obsolete" rubber products in the intake tract solves all the problems that have arisen.

It is much more difficult to eliminate the malfunction of the intake tract sensors such as MRV, idle, idle speed regulator. This is not about replacing gaskets, but about sensor malfunctions, due to which air leaks in the motors are possible. The masters do not undertake to eliminate air leaks in these devices, they just change them with new ones. It is possible to repair conductive paths, eliminate contamination or oxidation. The appearance of air leakage in VAZ cars in the fuel system is accompanied by the presence of leaks.

Important! If the driver ignores a fuel leak that has appeared, there is a risk of fire.

This can be the junction of the electric fuel pump with the fuel line, the fuel pressure regulator, and other places. Before starting work immediately after stopping the engine, depressurize the fuel system. Failure to do so may result in fuel ejection and ignition.

whether to let the machine stand for a while, the pressure will decrease on its own. Another place where a malfunction may be located may be the injectors of the power unit. To be precise, it is not the nozzle, but the gasket between it and the block head. These damaged parts are not particularly scarce, they can easily be bought in retail chains, so they are simply replaced. If the injectors are dismantled, and the vehicle's mileage is solid, it makes sense to flush them. This procedure is quite do-it-yourself in the garage.

This article is not a direct guide to action, it is for informational purposes only. Describe all possible reasons the appearance of the problem and how to fix them is difficult. If readers have questions, watch the video.

15 january 2018

IN modern engines internal combustion, electronically controlled, the amount of air entering the cylinders is strictly taken into account by special sensors. But when the air flow finds an alternative path through a loose connection of parts, normal work the power unit is disturbed due to a significant depletion of the combustible mixture. Determining air leaks in the intake manifold or other places is not an easy task, the symptoms that appear are too similar to many other problems. Nevertheless, the problem of diagnosing this malfunction is quite solvable.

Signs and causes of suction

When a leak develops in the engine, allowing additional air to pass through, the following symptoms are observed:

The first sign is "floating" idle speed. The motor draws in excess air, and the control unit, which analyzes the composition exhaust gases using a lambda probe, trying to cook correctly fuel mixture... But the mass air flow sensor (or DBP) does not take into account a part of the inflow, therefore the speed is unstable (about the signs of a sensor malfunction).
The share of fuel in the combustible mixture decreases, hence the difficult start of the power unit "cold" when enrichment is necessary.
Due to the depletion of the mixture, engine power is lost - the car is harder to get under way and accelerate.
As the driver begins to press harder on the gas pedal and forcibly increase the revs, the fuel consumption increases.

There are several reasons why the tightness of the joints is broken and the engine sucks in air:

deformation of adjacent planes (for example, the intake manifold to the cylinder head) as a result of overheating;
too frequent use of automotive cleaning chemicals that can soften gaskets and sealants;
leaky hoses or clamps on the vacuum take-off pipes in the engine.

On diesels, air is sometimes drawn in fuel pump through leaks in the line from the tank. In carburetors, the air flow path opens through worn axles and worn out dampers.

Where can air penetrate?

To check for engine leaks, you need to understand where to look. On engines equipped with an injector, air can be sucked in in the following places:

a gasket on the cylinder head flange where the intake manifold is attached;
body of the vacuum brake booster;
vacuum take-off hose for the amplifier;
throttle gasket;
through nozzles with weak sealing rings;
on the idle speed regulator flange;
through the stuck valve of the canister - adsorber.

Worn out carburetors whose seating flange has buckled from the impact high temperature, often let the air flow pass at the junction with the manifold. The second "sore point" is the throttle valves of both chambers, which become oval as a result of wear. Suction occurs through the side gaps and causes spontaneous flow of gasoline from the main diffuser, why the engine spins up to 2000 rpm at idle.

The weak link of a diesel engine is the fuel line from the tank to the high pressure pump. Plastic pipes and clamps lose their tightness over time and the pump, which creates a vacuum in the area, draws air through invisible cracks. It passes through the pipeline and through the nozzles is fed into the combustion chambers. the main problem consists in detecting a problem: leaking joints do not leak, since the external pressure is higher than the internal one.

Fault detection methods

As a rule, the possibility of air penetration through a loose connection is remembered last, when other problems are excluded - failure of sensors, regulators, and so on. Meanwhile, there is a simple way to find air leaks - with the engine running, slowly close the throttle valve with your palm. If the motor does not stall, then a gap has appeared in the area after the mass air flow sensor, into which an additional flow seeps.

Note. Hearing a whistle or hiss at the place of the suction is not an easy task, since the noise of a running motor interferes. Therefore, this diagnostic method is not suitable.

Start the engine and wait for the idle speed to stabilize.
Push at several points the rubber tube leading from the power unit to the amplifier housing.
If the operation of the engine does not change, then there is no suction in this section. An increase in crankshaft speed will indicate a malfunction.

Check all hoses that take vacuum from the motor in the same way. If the speed of the crankshaft changes when squeezing and then releasing the pipes, look for a loose clamp or a crack in the hose.

Find air leaks through throttle, the manifold and other engine parts will help the compressor. The delivery hose with the adapter is screwed in in place of any spark plug, then crankshaft pivots to position where inlet valve this cylinder is open. Injecting air at a pressure of 4–6 bar, treat all joints with soapy water - bubbles will immediately appear at the problem point.

Fill a 20 cc syringe with 3 gasoline.
Start the engine and wait for the idle speed to level out slightly.
Gently spray petrol on suspicious spots by squeezing fuel directly onto the gaskets.
If the suction goes through the intake manifold, then the pistons will suck in the spilled gasoline along with the air and the speed will increase noticeably. Be careful not to spill fuel on the electrical wiring.

The watering method works equally well for checking the manifold, nozzle seals, and throttle gasket. But it will not work to check the carburetor flaps with a syringe, since you cannot get to them. To make sure that there is a working out and the formation of side slots, the unit will have to be removed and the walls of the chambers are cleaned of soot.

The line supplying diesel fuel to the injection pump of a diesel engine is more difficult to check. A method using a compressor and soap suds is suitable here, but not every garage has such equipment. We'll have to go along the joints of the entire tube and diagnose the suction by the elimination method. Pour over connections diesel fuel meaningless - the effect will be insignificant and you will not hear changes in the operation of the motor.

One of the latest diagnostic methods involves the use of special device- a smoke generator. The connection is made, as is the case with the compressor, to the spark plug hole of any cylinder. After starting the smoke generator, it is not difficult to find the point of air penetration. It is recommended to use a halogen lamp to better see the rising smoke plumes.

A car is a complex mechanism in which everything must work perfectly. Otherwise, it seriously increases accident risk Moreover, one defective part can lead to premature wear of the entire system. To prevent this from happening, you need to be attentive to your iron comrade and fix all faults in time for their speedy elimination.

The engine is the heart of the car. Without its normal functioning, the very possibility of movement comes into question vehicle... Air leakage in the intake manifold plays a negative role in the operation of this unit. If this defect appears in your car, then the engine may stall in the middle of the road.

Essence and symptoms

The essence of the malfunction

When a suction appears in the intake manifold, much more air than it should. Naturally, this negatively affects the operation of the entire system.

Important! The result of air leakage in the intake manifold is a lean air-fuel mixture.

When this symptom is activated, the motor starts to work unstably. Depending on the severity of the breakdown, the list of possible symptoms can vary greatly. Therefore, it is not so easy to detect a malfunction.

Symptoms of engine suction

For many years, car owners and automotive experts a whole list of symptoms was compiled that may indicate that the engine is sucking air through the intake manifold:

The engine runs unstable at idle. With this symptom, you simply cannot set the idle speed below 1000 rpm. Each attempt will turn off the motor.
Temperature changes. The engine will start to overheat frequently. Plus it won't depend on the riding mode you choose.
Startup difficulties will be especially noticeable in the morning.
On the low revs the motor power will drop dramatically. At less than 2000 rpm, the car will not be able to develop speed.
Fuel consumption will increase significantly.
When driving at 2000 rpm and more, there are no problems.

Each of these symptoms indicates that there is an air leak in the intake manifold. Therefore, if you find at least one of them, you need to carry out detailed diagnostics and identify the problem.

We carry out diagnostics and eliminate the suction

Start the engine first. It should be idling. Then listen to the operation of the device. Very you can often hear the characteristic hiss of air.

Attention! You can find the breakdown by the source of the hiss.

In some cases, it is not immediately possible to localize the source of the noise. In this case, you will need to pinch the hoses that connect to the manifold. In most situations, problems are observed with the vacuum hose, which is responsible for strengthening the brakes. But exceptions are possible.

Occasionally, a power surge may occur when the clamp is removed. In this case, the problem lies precisely in this detail. Usually, this indicates such malfunctions as:

breakage of the adsorber valve,
failure of the vacuum amplifier,
holes in the hose.

If, after the performed manipulations, the problem is not found, it is necessary to use a sprayer. A flammable liquid is poured into it. It is best to use special carburetor cleaners.

Spray fluids with a thin construction site on potential places through which air is supposed to leak into the intake manifold. Special care must be taken to process:

cylinder head joint,
collector joint,
corrugation,
receiver seams,
throttle pipe joint.

As soon as the liquid enters the damaged area, it is drawn in and ends up in the motor. In this case, you will observe a jump in revolutions.

The most effective method

In order to use this technique for detecting air leakage in the manifold, you need to find a smoke generator. Then select any opening of the intake tract and through it, slowly begin to pump smoke into the system.

Attention! It is better to use as a consumable engine oil, it provides a large amount of smoke.

Further, to find air leakage in the intake manifold, take halogen lamp... With its help, you can easily find wisps of smoke. You will need special adapters for the procedure.

Eliminating the malfunction

Much depends on where you find air leaks in the manifold. For example, if the hole in the hose is small, you can use a sealant and cover up the damage. Of course, ideally, the damaged element needs to be replaced. Very often this operation must be done with couplings, o-rings and gaskets.

Outcomes

Air leaks through the intake manifold are easiest to diagnose with a smoke generator. Elimination of the defect directly depends on where exactly the breakdown was found.