Before buying a used car, you need to carefully check all its parts and assemblies for serviceability, from the body and interior to the engine and gearbox. If you prefer a vehicle with automatic transmission, then when checking it, you need to pay special attention to it, since the device is “capricious” and expensive. In the event of an automatic transmission breakdown, not every mechanic will undertake to repair such a complex device; it is easier to repair several manual transmissions than one automatic transmission. Even after high-quality diagnostics, its work remains in question, because it is no longer possible to achieve a similar standard assembly. The slightest grain of sand or chips that have fallen into the part can cause a repeated system failure.

Buying a car

An automatic transmission is like a weak link in a car, on the one hand, it is reliable to use, on the other hand, its design is complex, it requires proper care and delicate handling. With good operation without slipping in snow and mud, an automatic transmission can serve properly for more than a decade. But when buying a car from hand, there is no guarantee that the previous owner did not overheat this unit. All automatic transmission malfunctions are due to overheating, therefore, before buying a car with such a transmission, a detailed check is required. Many drivers, knowing all the complexity, prefer to abandon the supported machine by acquiring mechanics, because all its verification comes down to a banal test for smooth switching, checking the oil and listening to noises.

If you do not understand anything about the device, then for an objective assessment of the condition of the vehicle, it would be rational to use the services of a professional. If you have an idea about the system, then you need to start checking by clarifying information about the car and its previous owners. When the car is purchased not from the dealer, but from the owner, it is recommended to ask questions:

Visual inspection of automatic transmission

Checking an automatic transmission when buying is easy if you know what to check. Since the condition of the automatic transmission is highly dependent on the temperature of the type and quality of the oil, then you need to start the inspection from this. Inspection of the system occurs only during the day in dry weather. First, inspect the space under the hood, there should be no smudges and dirt on the box. You can even visually check the box from the bottom. Next, let's move on to checking the oil, there is nothing complicated here:

1. Selector set to position park.
2. The engine is started at idle and allowed to run a little.
3. They turn off the engine and remove the dipstick from the transmission, wipe it with a napkin and dip it back into the tank.
4. After that, they take it out again and wipe the oil from the dipstick with plain paper.
5. The oil should have a thick consistency, it should be red or brown in color, and should not have a burnt smell. When the light of the liquid is black and there is a smell of burning, there are also malfunctions in the operation of the automatic transmission.
6. Also look to see if there are otherworldly particles and dirt in the oil layer. If there are no metal flakes, everything is in order.
7. The oil level is also checked: on the dipstick it should be within the HOT marks if the box is warm and between the COOL marks if the car is cold.

Checking the automatic transmission in dynamics

There are models of gearboxes without a dipstick, so it is simply impossible to check the condition of the oil yourself. In this case, as an answer to the question: how to check the automatic transmission for serviceability when buying a car, all that remains is a test drive. Everything else must be entrusted to the auto service center.

Test run

The sequence of actions in which the automatic transmission must respond instantly. First, we check the device at idle:

1. We start the engine.
2. Set the transmission to Parking, a little warm up the car.
3. Having reached 650 rpm, we squeeze out the brake and switch the selector to the mode Drive. The car should then begin to sway forward.
4. We return to the mode N (Neutral)- the box itself should turn off.
5. Next, press the brake again and turn on the mode "Reverse"- the transmission should work without delay. There will be a feeling that the vehicle is going backwards.
6. Now we switch to the mode D.

If there is a delay of several seconds during the switching of modes, then the automatic transmission is faulty somewhere and needs to be repaired or completely replaced.

Automatic transmission check at the service station

The next step of the check is the check-in, it must be carried out as meticulously as possible, paying attention to all the little things. Before the test drive, it is advisable to choose a straight section of the road, without obstacles (traffic police posts, traffic lights, etc.) so that continuous acceleration to 100 km / h can be carried out. The sequence of checking the automatic transmission in dynamics:

Torque converter automatic transmission

An equally important part when checking an automatic transmission is the torque converter. It is a hermetically sealed knot, similar in shape to a donut. Its task is to transfer the rotational element from the engine to the automatic transmission, using two turbines rotating in oil. Control, over it and its optimization from the gearbox is carried out using a computer control unit. If there are any problems in the system, the automation signals an error or completely blocks the engine when changing the automatic transmission operating modes. It is difficult to determine the breakdown of the torque converter at the mechanical level, by means of diagnostics, for this you need to disassemble the system and inspect it. You can only check the automatic transmission torque converter by external signs:

Solenoid adjustment cable condition

When checking an automatic transmission, it is important to assess the condition of the cable that controls the throttle valve. This element of the system can wear out, and then the transmission starts to work incorrectly. In addition, a weakening of the cable is possible, it can be determined if the automatic transmission turns on low or high speeds not when it is needed. A loose cable leads to overheating of the box and an increase in fuel consumption. The cable must not only be tensioned, but also lubricated. The automatic transmission solenoid is a mechanical valve-regulator that opens and closes the channel in the hydraulic plate at the signal of the control unit, for the passage of oil flow. Automatic transmission solenoids can only be checked using diagnostic equipment. It is best that this be done by a specialist at the service station.

This test of the car is carried out when turning off extraneous sound sources. This applies to musical accompaniment on the radio, loud conversations, etc.

How to check the automatic transmission for serviceability. The procedure for inspecting a car standing still:

1. Engage the brake pedal.
2. in all gears with a delay in each position of 5 seconds. In this case, the transmission should work quickly. A delay of at least one second is allowed. At the same time, make sure that there are no extraneous sounds such as creaking.
3. Repeatedly walk the automatic transmission lever through all speeds without stopping in each mode while listening.
4. Create the following combination of modes using the automatic transmission selector: D - R - D. The permissible delay interval is no more than 1.5 seconds. In this case, it is necessary to exclude extraneous sounds, jerks.

In the process of self-checking the car at idle, only smooth slight vibrations can be allowed. If strong, intermittent shocks are noticed, there are serious defects in the design of the automatic transmission. A serviceable automatic transmission is distinguished by quiet, ideal operation.

Checking a used car with automatic transmission while driving

At the next stage, the car is checked in dynamics. For this, a flat area is selected, where nothing can interfere with continuous acceleration to 100 km / h. There should be no traffic lights, pedestrian crossings, traffic police posts, etc. on the way.

The set of measures for checking a car with automatic transmission includes the following driving modes:

• acceleration with a soft start;
• braking after rapid acceleration;
• downshifting with free movement forward;
• overdrive check.

Checking the automatic transmission during a soft start with subsequent acceleration:

1. From position P, the automatic transmission lever is moved to point D.
2. The gas pedal is pressed down to a speed of 60 km / h. In this case, a double smooth transition is observed without sharp shocks from I to II and then to III speed.
3. Acceleration gradually increases up to 90 km/h. On the way to this mark, the automatic transmission goes through all the gears. At the same time, the task of the buyer is to exclude shocks and extraneous sounds during the transitions between gears.
4. The tachometer readings for a 4-speed gearbox at 95 km / h correspond to 3,000 revolutions, for a 6-speed automatic transmission - 2,000, respectively.

At the next stage of the test, a sharp acceleration of the car is performed immediately after the start. In this case, the automatic transmission selector switches to mode D and at the same time the gas pedal is pressed into the floor. A serviceable car quickly starts from a standstill and gains almost 6,000 rpm. The result of the obtained dynamics must be compared with the parameters declared by the manufacturer. If the car does not accelerate when gas is supplied, it can be argued that the clutches, automatic transmission needs to be repaired or replaced with a new unit.

After accelerating the car, you should drop to 40 km / h and sharply press the brake pedal - this is how the ability of the car to brake urgently is checked. The car should obediently slow down and stop.

Checking the ability of the automatic transmission to downshift:

• develop speed up to 100 km / h;
• take your foot off the gas pedal;
• start the car by inertia;
• a working automatic transmission switches step by step to a decrease, while the tachometer shows how the corresponding indicators fall.

To test the automatic transmission overdrive function, you need to set the button of the same name to the ON position at a speed of 70 km / h. The automatic transmission should immediately respond and shift to the next gear. As soon as this button is turned to OFF (off), the automatic transmission will switch to a lower gear. The appearance of a flashing signal from the Check Engine sensor indicates a malfunction in the automatic transmission.

The presented verification methods provide a high degree of probability (at least 80%) that the automatic transmission and the entire transmission are in good condition or, on the contrary, there are defects in this car.

Tip: At the initial inspection of the car, it is recommended to check the wheels. This is especially true for SUVs. If their tires are designed for off-road conditions, it is necessary to more carefully check the serviceability of the components and the performance of the automatic transmission.

Instruction

An automatic transmission is a very complex device, consisting of numerous parts and seals. Wear of just one element leads to incorrect operation of the entire unit. Also, the automatic transmission is sensitive to overheating. Half an hour of slipping in the deep is enough to burn the box. The oil in an automatic transmission should be changed more often than in a mechanical one, and driving on the "old" oil is more deplorable. The wrong choice of oil poured into the box can ruin it on the very first day of operation. In addition, machines do not tolerate repairs well and do not last long after it. Therefore, practical Americans and Europeans do not repair the box, but change the assembly.
It should also be remembered that the repair of an automatic transmission is very difficult and very expensive.

Before checking the automatic transmission, it is useful to find out the cars. This can save time and money. If the car was used at a rental or was restored after a serious accident, the automatic transmission will not last long. The same can be said about the already repaired box. All repair automatic transmissions have problems. And not all workshops can professionally repair automatic transmissions. The presence may indicate increased wear on the machine caused by the transport of a trailer.

Checking the automatic box.
First, you should check the oil level in the box and its condition. In this case, the engine must be idling, the selector of the machine should be in the “parking” position. The transmission dipstick is removed, wiped with a clean cloth and inserted back. Now pull out the dipstick again. To assess the condition of the oil, the dipstick is wiped with white paper. The paper should leave a clean and transparent mark without metal or foreign particles. New oil is red. Not new may be brownish, but not black. And it doesn't have a burnt smell.
Please note that modern automatic transmissions do not have an oil dipstick. Checking the level and condition of the oil is possible only in a specialized technical center.

Testing automatic transmission on the go.
The delay between the moments of selecting the position of the selector "D" or "R" and before turning on these positions of the selector is a sign of a defect. First, you should warm up the car and the box in the "P" (parking) position until the speed drops to 600-800. Holding the car in place with the brake pedal, the selector switches to "D" (driving). The machine should immediately select this mode and start trying to drag the machine forward. Everything should happen smoothly, without pushes and knocks. Further, when switching to "N" (neutral), the box should turn off. Now, when you turn on "R" (reverse), the automatic transmission should also turn on instantly, without clicks and knocks. The car should try to crawl back.
While holding the brake pedal, you should check the box, switching from "D" to "R" and vice versa. There should be no jolts or knocks. Delay more than 1 sec. when you turn on any mode, it indicates wear or damage to the box.

To further check the box on the go, it is necessary to develop a speed of up to 50-60 km / h. Gears should shift at least two times, smoothly, without shocks and delays. The fact of a gear shift is determined by a slight change in the noise of the motor and a drop in its speed. With excessive wear of the automatic transmission, a push, delay or shock is felt at the moment of shifting.
At a speed of 40-50 km / h, you should drown the accelerator pedal to the stop. A properly working machine will shift to a lower gear, engine speed will increase.
If there is an overdrive mode (button to the left of the automatic transmission selector on Japanese and American cars), it is also checked. To do this, at a speed of 60-70 km / h, the ON mode is turned on by pressing the overdrive button. The transmission should shift up one. When overdrive is turned off, the gear shifts one down.
The problem of slipping gears is as follows: when you press the gas pedal, the speed increases, but the speed does not increase.

Buying a used car is a true art that requires some knowledge and luck. It is extremely rare that the owner of the car reports all his problems, and often he himself does not know about many of them.

One of the most expensive parts of a car is the gearbox. When buying a car from a former owner, it is recommended to involve specialists who can diagnose the body, engine, suspension and transmission, including. But there are times when it is not possible to inspect the car with professionals. In such a situation, the driver himself must carefully diagnose all the units, including the automatic transmission. Below we will tell you how to check the machine on a used car.

Checking the oil in the automatic transmission

The first thing to do when checking an automatic transmission is to look at the oil in it. The oil test must be carried out according to three parameters - level, condition and smell. In this case, a prerequisite for testing is a warm engine. Before proceeding with the procedures below, start the engine and place the transmission in the "Park" position. Warm up the oil in the gearbox to operating temperature, then turn off the engine and proceed to the tests:

The checks listed above on a “maintenance-free machine”, which does not have a probe, are slightly complicated. At least in such a transmission, you can check the smell of oil.

What to ask about automatic transmission from the owner of the car

Having made some conclusions for yourself based on the tests described above, you can proceed to communicate with the owner of the car to make sure how much his testimony matches reality. Be sure to ask the seller:

It should be remembered that some drivers may not be aware of the problems that their transmission has, so it makes little sense to ask about the presence of faults in the box, it is better to check everything yourself.

Checking automatic transmission in a car

After questioning the driver and checking for signs of wear on the automatic transmission oil, you need to look at the operation of the gearbox. To do this, sit in the car in the driver's seat and follow the following procedures:

The above are the main ways to check the automatic transmission before buying. Naturally, under ideal conditions, you need to test the car with diagnostic devices and raise it on a lift to make sure there are no smudges from the gearbox.

When choosing a vehicle in the secondary market, first of all, you need to pay attention to the automatic transmission. The fact is that this unit is quite demanding on maintenance and easily fails if used improperly.

Buying a car with a problematic automatic transmission is highly undesirable. Repair or replacement can cost a lot of money and waste a lot of time. But unfortunately, among the offered used cars, there are often cars with a problem in this area.

What is "Automatic Transmission"

To date, four types of gearboxes have become widespread:

Mechanical;

Variable speed drive;

robotic;

Automated.

Most often, using the expression "automatic transmission", it means one of three options other than mechanics. The main difference from mechanics is the absence of a clutch pedal and the need to independently switch the gearbox stages. All the driver's action at the start is reduced to switching the scenes to the start of the trip mode and pressing the gas pedal. Switching steps or "virtual" steps occurs automatically in various ways.

Depending on the type of box and model, the number of options for the position of the backstage may vary, but there are several basic ones that are present in almost all cars.

1. Parking mode (P) - the box and wheels are blocked, and the car cannot roll;

2. Reverse (R) - switches the box to the reverse mode;

3. Neutral gear (N) - corresponds to the mode on the mechanics.

The automatic transmission is very convenient to use, the driver is relieved of unnecessary concern about shifting gears, and the shift itself occurs as smoothly and almost imperceptibly as possible. But the main disadvantage is the complexity of maintenance and repair. There are very few masters capable of repairing a machine with high quality, and not all masters are willing to take on this work. Most often, service stations advise changing to a new one and not trying to repair it.

Checking the automatic transmission

Action one - survey of the owner of the car

First of all, you need to ask the owner of the car about some aspects of using the car and maintaining the machine. You need to ask about the features of the operation of the machine, about the regularity of maintenance and about the ongoing repair work of the box.

Survey of the owner about the features of operation

We advise you to initially find out about the number of owners of the car, and the specifics of its use. It is not advisable to buy a car that worked in a taxi or transported goods on a trailer. Also, the gearbox receives critical loads when using the car for hunting, fishing and other outdoor activities. In the case when the car has changed many owners. Then there is no guarantee to get truthful information about the history of the car.

As for cars with automatic transmission and extreme conditions, this is a difficult question, there are specialized vehicles for this, where all components were specially developed for such conditions. As for ordinary cars, automatic transmission and critical loads are incompatible. Even slipping in a snowfall in an attempt to get out of a snowdrift for half an hour can lead to a critical overheating of the transmission oil, which can lead to serious transmission problems.

Survey about automatic transmission maintenance

The most important point in maintenance is the timely replacement of transmission oil, which in most cases should be carried out at least 60,000 km. If not replaced, then by 100 thousand kilometers, serious problems with the box will begin, which will result in significant repair or replacement costs.

If the oil has been changed, be sure to ask about the reasons for the change, the mileage during the change, and about changing the oil filter.

For replacement, a special automobile oil with special additives is used, such oil is designated as ATF. Many machines are adapted to changing the oil only at official service sites (sometimes you have to enter information about the change into the control computer), and another main positive point for changing the oil in a certified service is the availability of a check, order and possibly a guarantee.

Auto repair question

If you receive an affirmative answer to your question about the repair of the machine, the best action would be to refuse the purchase. In this case, you will acquire a problematic unit with an unknown quality of work performed, and the possibility of a quick failure will increase significantly. Do not pay much attention to the repair documents provided and the possible warranty, this will not save you from poor-quality repairs.

A radically different effect is obtained when the box is completely replaced with a new one in the official service. In this case, calmly proceed to the next stages of verification.

Step two - oil check and external inspection of the box

Simple visual inspection of the machine

Inspection is recommended to be carried out during daylight hours, this will help to better inspect the unit and worry less about additional high-quality lighting. Of course, it is desirable to provide all inspection procedures to professionals at a service station, but you can do it yourself.

Any inspection and check is carried out exclusively on a warm car, for this it is necessary that the car idle for about 5 minutes in the warm season and about 15 in the cold.

After warming up, with the engine running, inspect the box from the engine compartment and under the bottom of the car. There should not be any oil leaks on the box, and the contamination of the body should not exceed the total engine compartment.

Oil check

The next step is to check the transmission oil. At the same time, there are several nuances, the fact is that automatic transmissions are conditionally divided into serviced and not serviced. At the same time, oil in a maintenance-free box can only be checked at a service station. It is worth noting that the owners of maintenance-free boxes can sincerely believe that in such units there is no need to change the transmission fluid, which can lead to serious problems. Therefore, consider this carefully.

And so, when inspecting the transmission, it is necessary to pay attention to the level, consistency, color and foreign elements in the oil. Recall that in the case of a maintenance-free transmission, you must contact a service station.

In other cases. Be sure to have a special dipstick to monitor the condition and level of oil. The oil level must be strictly within the maximum and minimum levels marked on the dipstick. As well as the lack of fluid in the transmission, so too much of it is harmful to the mechanism.

The transmission fluid should be moderately thick and should not run off the dipstick. Also, the color of the oil is important, it should be from light red to dark red. In the event that the liquid is brown, but does not have foreign inclusions and is transparent, this is an acceptable condition, but requires urgent replacement.

Pay attention to extraneous inclusions, if during the inspection you find such or the smell of the liquid is burnt, then we advise you to refuse to buy a car. Most likely in this case, the friction discs that replace the clutch have already burned in the machine.

Step three - check on the go

Testing an automatic transmission at idle

The next important step is to check the machine at idle. This must be done in almost complete silence in order to be able to hear all the extraneous sounds emitted by the transmission.

All checks are carried out with the brake pedal depressed:

1. It is necessary to gradually switch the gearbox to all modes with a delay of about five seconds. In this case, the transmission should work clearly and switch modes with a maximum delay of one second. During switching, no suspicious sounds and sharp shocks should be made.

2. More stringent check, all automatic transmission modes switch quickly, without delay, several times. At the same time, also, no extraneous noise should be heard and no shocks should occur.

3. Another difficult test for an automatic transmission is shifting the gearbox in such a D-R-D pattern. In such a situation, switching modes should occur at a speed of up to 1.5 seconds, and also no suspicious sounds or shocks.

Remember that any serviceable transmission works quietly and clearly. At this stage, you need to trust the feelings, and if it seemed to you that the transmission was behaving suspiciously, then it is so. Otherwise, you will not be able to find fault with anything.

Machine test on the go

Now let's move on to the main part of checking the car. In which the operation of not only the automatic transmission, but the entire car will be checked while driving.

For these tests, you must select an empty section of the road. Where it is possible to safely accelerate to 100 km / h, while not causing interference. It's necessary. Since you will have to check the car in a smooth acceleration and stop, in a quick acceleration and a sudden stop, in a quiet ride when lowering the steps and use the Overdrive mode.

Smooth acceleration and deceleration

The check takes place in mode D of automatic transmission, by switching to this mode, smoothly touch the car. Slowly and slowly increase the speed to 60 km / h, while several steps should already have been switched. Pay attention to the operation of the box at the time of switching, there should be no sharp shocks or jumps in the tachometer, and the sound of the transmission should not arouse suspicion. Do the same when accelerating the car to 100 km / h, then smoothly stop the car, not forgetting to listen carefully and pay attention to the suspicious behavior of the car.

Quick start-brake

The test is carried out in mode D, before starting, sharply press the gas pedal (just do not break it). With a fully functional transmission, the car without unnecessary delay will raise the speed to 5-6 thousand per minute and will pick up speed with good dynamics. It is possible to detect the acceleration time to 100 km / h and then compare it with the data specified by the manufacturer, while there should not be strong deviations from the declared result. After that, you need to reduce the speed of the car to about 40 km / h and brake sharply. If there are no problems, then the car will stop without problems, and the gearbox will reset all steps and will not make any extra sounds.

In the case when the car does not pick up the required dynamics from the start, this means that the clutches are slipping in the automatic transmission. In this case, a quick repair is inevitable.

Gradual downshift

Some experts believe that this check is already redundant, but any opportunity to find out problems in the automatic transmission should not be neglected. For this test, you need to accelerate the car to about 100 km / h and release the gas pedal. When the speed decreases, the transmission steps should gradually decrease, and the moment of transition should not be accompanied by unnecessary sounds and rough shocks. The drop should be almost imperceptible.

Overdrive check

If there is a function, it must be tested. This function allows you to shift to a higher gear. In a four speed automatic, this feature will replace fifth gear.

To check, it is necessary to accelerate to 60 km / h and press the function activation button by turning it on and then turning it off. At the same time, suspicious things should not happen to the transmission, and the “Check engine” indicator should not light up on the instrument panel. Otherwise, this is an indicator of a malfunction of the automatic transmission.

Conclusion

Using the information received, you will be able to confidently check the car with an automatic transmission for faults. Also, the check will give almost complete confidence in the purchased vehicle. But do not forget about the possibility of diagnostics at service stations, experienced craftsmen will be able to test the entire car faster and in more detail, this will help save time and give more guarantees.