The design of cars is constantly being modernized. Today there are many complex but effective structures and functional units that require special care. The transmission or system that allows you to change gears in a car is a special unit that requires attention from the vehicle owner.
As a mechanic, I have encountered many problems arising in the gearbox. One of the most unpleasant breakdowns can be called oil overflow. Beginners often have no idea what the risk of such a breakdown is. In this article I would like to talk about why the oil level in an automatic transmission should not be higher than normal and what consequences an overflow of lubricant can have.
How much lubricant should be poured into the automatic transmission?
You should not check what will happen if you pour oil into the automatic transmission. This can lead to irreversible consequences, and therefore to major repairs. Information about the exact volume of lubricant that needs to be poured into the desired vehicle is specified in the instructions for the vehicle. Much depends on the structural features of the transport and on the method of replacing the fluid.
On average, an automatic transmission uses up to 6-8 liters of lubricant, and as a top-up, it will be enough to use up to 3 liters. When performing a partial replacement, it is not necessary to drain the old lubricant in full. It is enough to add liquid and make sure that the level meets the standards.
Persistent MYTH
How many times have I heard in conversations that if you fill the engine with 5-10% of the “transmission”, the compression will increase, traction will improve, and fuel consumption will also decrease! Just a miracle remedy! But guys - THIS IS DANGEROUS, you shouldn’t do this, you’ll understand why below.
These are “outbid” techniques, which in this way restored very “dead” engines with mileages of 300 – 400,000 kilometers, in which the oil pressure lamp shines like on a “Christmas tree”. This addition helped to temporarily increase the thickness of the engine oil, due to which the pressure increased and the lamp stopped shining! But how much will this be enough? At 500 - 1000 kilometers - and then what? Capital? In general, read on - it’s definitely useful!
Signs of lubricant overflow in an automatic transmission
A slight oil overflow may not have serious consequences. A slight excess means + 1-1.5 cm above the norm. However, it is also not easy to notice such an excess. Usually, drivers remain unaware that the oil is filled slightly above the norm. The situation is completely different when the lubricant significantly exceeds the permissible level.
The consequences of overfilling can be quite serious, so it is extremely important to take the necessary measures quickly. As the main “symptoms” of lubricant overflow, it is worth noting:
- the pressure in the system begins to increase, as a result of which leaks form and liquid begins to ooze from the seals and from under the dipstick plug;
- the lubricant begins to foam, bubbles appear, which do not reduce the quality characteristics of the lubricant. The density of the composition also becomes significantly less;
- The automatic transmission is unstable. The driver records jerks and jolts during the trip. May be accompanied by noise;
- Heat transfer is disrupted and the box begins to heat up.
Any irregularities in the operation of the automatic transmission may indicate problems associated with the level of lubrication in the system. This can lead to serious damage to the functional unit, which means the driver must immediately respond to such violations.
Device
Modern automation uses completely different operating principles than a manual transmission - it is much more complex and, accordingly, more expensive. Let's look at the main parts that are present in all automatic units.
- The hydraulic transformer is the main component, without which work is simply impossible. This is an analogue of the clutch that is used with a manual transmission, but it is more complicated. Its purpose is to transmit torque from the engine to the drive wheels using a working fluid - oil.
- The planetary gear set, or gear, distributes the incoming force from the engine to other structural elements of the gearbox, while changing the gear ratio. In a manual transmission, this is a set of gears that interact with each other when changing gears.
- Friction disc, or clutch, - with the help of this element the gears are changed. It is controlled by an electronic unit.
- Overrunning clutch is one of the components that make up the torque converter. Protects the friction clutch, as well as other parts of the automatic transmission, from sudden shocks and vibration when the gear ratio changes (gears are switched).
We will not understand the intricacies of the automatic transmission. The main thing is that it is more complex than a manual transmission. This leaves its mark on its advantages and disadvantages.
Reasons for exceeding the oil level in an automatic transmission?
Overflow of lubricant into automatic transmissions in the vast majority of cases is caused by non-compliance with the rules when replacing the substance. The fact is that the liquid must first be allowed to drain as much as possible, and only then the required volume must be added. If this rule is not taken into account, then an excess of the norm will be obvious.
It is recommended to pour new lubricant very carefully and gradually. The substance penetrates and is distributed through the channels, which is why you need to pour it in, and then wait until the composition is evenly distributed in the system.
Another reason for this violation is that the oil increases in volume as it expands. Many drivers forget about this fact, resulting in overflow.
Concrete overflow
This is already an option when the oil is poured right up to the lid. And there is no way to wait until it develops naturally. The moving parts of the automatic transmission begin to whip up the transmission oil, forming foam in it. With such airing, ATF increases in volume while losing pressure. The danger of this phenomenon is increased by the fact that foaming does not begin immediately after starting, but during the movement, and it is especially strong at high speeds. It is quite difficult to immediately notice the consequences. And they will be like this:
- the most harmless thing is squeezing out the oil through the breather, seals and dipstick. As a result, the box will be covered in oil, but this is a solvable and not the most dangerous problem;
- the machine will start to stall. Some of the speeds may be lost; the box will not switch to a certain position at all. All this is accompanied by the display of error codes on the check engine, and at this stage, too, nothing bad happens yet - if you paid attention and took action, consider that you saved the box;
- Further ignoring the overflow leads to overheating of individual automatic transmission components. The friction discs fly first, then the accompanying elements begin to fall;
- Hence the conclusion: if you don’t want to delay a major overhaul of the gearbox (or even buying a new one), monitor the oil level in it regularly. And do it technically competently.
How to check the lubricant level in an automatic transmission?
For the most accurate results when checking the lubrication level in the transmission system, you will need to use a special device - a dipstick. Before checking, it is important to pay attention to the manufacturer's advice on this issue. Most probes have an o and a "HOT" on them. It is important that the lubricant level is between these marks.
It is recommended to check the oil level when the transmission is warm or after starting the engine, after 3-5 minutes. The procedure should be as follows:
- The car must be placed in neutral.
- Remove the dipstick and wipe the dipstick dry. Return the tool to its place.
- Pull out the device and study the data.
- If there is not enough lubricant, then you need to immediately add the substances. When the grease is higher than normal, it is important to remove it as quickly as possible.
After completing the required action, it is necessary to repeat the verification procedure, but the car must travel about 10 km.
Useful tips
When checking, the oil level on the dipstick should normally be between the HOT and COLD marks. A shift towards HOT of 2-3 mm is allowed, but not higher. In this case, you need to check the oil only on a well-warmed automatic transmission.
In order for the fluid in the machine to fully heat up to operating temperature, you must drive the car at least 10 km. Then the car should idle for about 5 minutes, after which you should move the selector through the main automatic transmission modes, lingering in each for about 2-3 seconds.
Then the engine is not turned off, leaving the selector in position P. Now you can get out of the car, remove the automatic transmission oil dipstick, wipe it with a clean rag (lint-free) and insert it back until it stops for 2-3 seconds. The dipstick can now be removed again and the ATF level checked.
As for the COLD mark, this indicator is a service indicator and is necessary in order to fill the main amount of oil into the unit as part of automatic transmission repair or maintenance. Next, the oil is added a little more, then the box is warmed up, after which the level is further adjusted. It turns out that following the COLD mark and checking the oil level “cold” is a mistake.
We also recommend reading the article about what color the oil in an automatic transmission should be. From this article you will learn about the subtleties and nuances that you need to pay attention to when checking the condition of the oil in an automatic transmission.
It also happens that there is only one mark on the dipstick. So, in this case, you should focus on it. Also an important recommendation (especially for maintenance-free boxes without a dipstick) is the rule to fill in exactly as much oil as was previously drained.
We also note that automatic transmissions should only be filled with oil recommended by the car or transmission manufacturer itself. If an analogue is selected, the fluid must be of high quality, original, and also fully comply with all tolerances and recommendations of the gearbox manufacturer.
Remember, in an automatic transmission, the torque from the internal combustion engine is transmitted to the transmission through ATF, and the oil in the automatic transmission has unique protective and cleaning properties, retaining dirt, products and deposits.
What consequences can overflowing lubricant into an automatic transmission have?
The consequences of such a violation can be very different. The most common problem is poor gear shifting and a malfunction of the gearbox. Other difficulties include:
- failure of friction discs, which indicates that other devices will quickly become unusable;
- increased fuel consumption as lubricant gets into the fuel;
- a malfunction of the cylinders appears when the mixture hits the spark plugs.
It is worth noting that the problem does not always appear immediately. Sometimes, breakdowns begin to appear during further use.
Trivial mistakes
An equally disastrous moment for an automatic transmission can be filling with the wrong oil, that is, mechanical oil will simply kill it and quickly:
- How can one confuse, quite simply, the human factor, the most destructive factor in the world?
- The seller gave you the wrong oil, because you were distracted by the phone or another buyer, you didn’t check and trusted the seller.
- At the Technical Service Station they trusted you - they filled in without looking what the owner purchased, you say that doesn’t happen?
- As it happens, it’s not for nothing that they say what will happen if a child has too many nannies.
In my memory there was such a case:
- A novice mechanic is sent to pick up oil from a warehouse according to a delivery note; the warehouseman waves his hand and indicates, pour it from that barrel.
- There are three barrels in that direction, all with hand pumps, and he fills from the nearest one.
- He brings it to the master, he relies on the storekeeper, and with a wave of his hand he trusts the newcomer to fill in the lubricant, and the operation is simple, and he will practice, and this is how the box oil gets into the engine, and vice versa.
How to remove excess lubricant from the system?
A slight overflow is not a big deal, but when the problem may require quick intervention. You can fix the problem yourself by removing the oil filter. The liquid will completely drain from the system, after which it remains to install it in place.
If such actions do not solve the problem, you will have to remove the grease using the “suction” method. For this, a regular dropper and syringe are used. Excess liquid is removed through the dipstick hole. The manipulations are not complicated and do not require a visit to a service station.
Ways to remove excess oil
With a slight overflow, the problem is not acute, so there is no need to panic. When an excess of liquid is detected in a timely manner, there is no need to involve service employees in the process. If a motorist has poured oil into the automatic transmission when replacing it, he is able to completely cope with the task on his own. Often the solution is to remove the oil filter. When the liquid completely drains from the filter element, it is replaced. If such manipulations do not help eliminate the problem, the excess amount of lubricant is removed by sucking it out.
To remove excess oil yourself in this way, you will need a 10 cc syringe and a dropper. Next, we perform a number of simple steps:
- cut off 60 - 70 cm from the tube;
- we lower it with one end lower into the hole for the dipstick (if there is none, we use the filler hole);
- We put the second end of the tube on the syringe without a needle and use the piston to remove excess oil;
- During the process, we check the fluid level so that later you don’t have to add lubricant.
If the volume of oil poured is more significant, then the excess will need to be drained through a special hole.
The procedure for removing excess grease is quite simple, so even a novice motorist can cope with it. The main thing is to observe the condition of monitoring the fluid level, so as not to cause troubles associated with a lack of lubricant. It is necessary to check the volume and condition of ATF at the intervals established by the car manufacturer's regulations or more often in the presence of unfavorable operating conditions of the vehicle.
