Oil leaks between gearbox and engine. Oil leak from a car engine: causes of a malfunction and how to fix it

During the operation of the vehicle, the driver may notice an oil leak between the engine and gearbox. We note right away that a similar malfunction appears on different cars, and no matter what type of engine (,) and gearbox are installed.

In other words, oil leaks at the transmission junction and on different cars when the car is equipped with a manual transmission, a manual transmission, a robotic gearbox with one or two clutch discs, a manual transmission, an automatic transmission with an automatic transmission torque converter, a continuously variable variator, etc.

In any case, if oil drips between the engine and gearbox, then this is a sign of a serious breakdown. Faults of this kind require immediate diagnosis and quick elimination.

Next, we will talk about why an oil smudge may appear between the power unit and the gearbox, and also what the driver should do if smudges of fresh lubricant are visible between the engine and the gearbox, oil is actively running or the lubricant on the parts is covered with dust (the leak is insignificant, there is fogging).

Read in this article

Oil flows between the box and the motor: why is this happening

For a better understanding and quick identification of the problem, let's start with the features of lubricating fluids in gearboxes and internal combustion engines. The fact is that the operating conditions of the transmission and the power unit are significantly different. For this reason, engine oil is poured into the engine, and special transmission oil is poured into the gearbox. For both the motor and the gearbox, the lubricant may have.

However, this is where the similarity ends. Please note that these fluids differ greatly in their basic properties (viscosity) and chemical additive packages. This is due to the fact that in the engine, lubricant is supplied to loaded components and parts under pressure, and to elements with lower loads it is supplied by spraying.

At the same time, engine oil becomes very hot, subject to oxidative processes, etc. In most transmissions (except for torque converter automatic transmissions), mating parts are lubricated by spraying lubricant during the rotation of the nodes, the loads on parts inside the transmission are much less compared to internal combustion engines.

Such features of work also determine the overall service life of lubricants in each unit (on average, 10 thousand km for engine oil and 50-80 thousand for transmission oil). We also note that for each node, the vehicle manufacturer determines individual tolerances for viscosity and other lubricant parameters.

The viscosity of the engine or transmission oil is not suitable

Now back to our main problem. It is quite obvious that if a leak appears between the gearbox and the engine immediately after switching from a “thicker” SAE oil to a low-viscosity lubricant (for example, mineral water was replaced with liquid synthetics), then there is a high probability of a banal mismatch of the filled material with the recommended parameters.

Simply put, the use of low-viscosity lubricants in gearboxes and internal combustion engines can lead to leaks. So what does this information give us? Most importantly, if the oil in the motor or gearbox turns out to be unsuitable, then leakage can be easily eliminated by replacing the lubricant with the recommended one.

If no other prerequisites for the appearance of leaks have been identified, then it is appropriate to talk about a malfunction. At the same time, the analysis of the oil itself allows you to determine where it flows from, from the box or the engine. Let's dwell on this in more detail.

There was a malfunction in the internal combustion engine or gearbox: how to accurately determine

If the liquids poured into the engine and gearbox meet all the parameters, then oil leakage at the junction of the engine and gearbox is the result of a breakdown of one of these units. Less often, but it is quite possible that problems can occur simultaneously in both nodes at once.

As already mentioned, the lubricant in the gearbox and internal combustion engine differs in consistency, color and smell, which allows us to draw some conclusions. For primary diagnosis, this is very important, since it is possible to more accurately determine which unit leaked and why. To do this, you need to carefully examine the streaks, the color of the oil, dust and dirt on it.

Now let's move on to verification. We note right away that limited access usually prevents the exact cause from being determined. In other words, it may not be possible to visually inspect the junction of the engine and box. In such a situation, the easiest way to determine where the fluid is flowing from is.

To do this, the level is estimated by the dipstick, a decrease in the indicator will indicate problems with the motor. We add that the gearbox on some cars may also have its own oil dipstick. However, such a check allows you to accurately determine the problem unit when the oil flows out intensively. In this case, you can usually also notice oil stains under the front of the car.

If only streaks were found on surfaces and parts at the junction of the transmission and the power unit, then the lubrication level does not always drop significantly. In such a situation, an additional assessment of the leaking fluid helps.

Motor oil has a lighter reddish-amber hue, it is fluid, its smudges conditionally “absorb” dust and dirt. Transmission oil is usually darker, may have a reddish tint (ATF oil). Such a lubricant is thicker, has a characteristic pungent odor, smudges quickly become overgrown with a thick layer of dust, accumulating dirt on its surface in the form of a “fur coat”.

Note that the following method is also often used in practice. Part of the flowing liquid must be collected in a container into which water was previously filled. When it enters the water, engine oil coagulates, retaining the shape of a drop, after which it sinks down. The transmission fluid does not sink to the bottom, spreading over the surface in a spot.

Oil leaks from the engine or gearbox: the main causes and repair

The appearance of various leaks at the junction of the gearbox and engine most often occurs for the following reasons:

• wear or failure of oil seals (for example, crankshaft rear oil seal);
• there were various defects of shafts and seals;
• the appearance and increase in the backlash of the shafts (primary shaft, etc.);
• there was a weakening of the fasteners;
• seals and gaskets have lost their properties;
• there was a depreciation of the stuffing box on the input shaft of the box;
• the main oil seal may be worn out;
• during repair, the oil seal or gasket is incorrectly installed;
• the geometry or integrity of the pallet is broken;
• oil squeezes out as a result of problems in the crankcase ventilation system;
• there was a depreciation of the shafts at the junction of the box and the engine;
• the oil pump or torque converter in the automatic transmission is out of order;

First of all, you need to determine where the oil is flowing from. Then you can proceed to find the cause and troubleshoot.

Lubricant is leaking from the engine

Let's start with the powertrain. As a rule, a leak often occurs in case of problems with . The specified element usually fails on units with solid mileage.

The crankshaft seal is made of oil resistant rubber. However, during operation, the part loses elasticity and hardens, and can also be squeezed out as a result of wear of the crankshaft thrust rings. As a result, after the engine warms up, the oil flows out.

We also note that problems with the crankshaft rear oil seal can be caused by a situation when the car is idle for a month or more without starting the power unit. The fact is that during such downtime, all the lubricant drains into the crankcase, the seals become dry, they are deformed or destroyed.

Also, a leak from the internal combustion engine occurs due to the fact that pressure rises in the crankcase of the engine. An increase in pressure is usually associated with the fact that there is an intensive breakthrough of exhaust gases from the combustion chamber through worn ones, and overall wear is additionally affected. Another reason could be that the crankcase ventilation system is not working properly due to contamination.

We add that a situation with increased pressure may also arise in the checkpoint. If the pressure rises, then the seals, gaskets and seals cannot cope with the load and allow the lubricant to pass out. Lubricant can flow out very actively, which increases the risk of a more serious breakdown of the problematic unit. In other words, if the problem is not fixed in a timely manner, then a gearbox overhaul may be necessary.

It is important to understand that oil leakage through the rear oil seal can lead to a rapid decrease in the level of lubricating fluid in the crankcase. On manual transmissions and manual transmissions, lubricant from the motor can also get on, causing loss of traction, slipping and jerking while driving.

If these symptoms match those on the dashboard, then it is urgent to check the level of lubrication in the engine. Drips in the area of ​​\u200b\u200bthe junction of the box and the internal combustion engine will indicate that it is urgent to replace the rear crankshaft oil seal.

As for the crankcase ventilation, then it is necessary to check the oil deflector in the valve cover and assess its condition. If a dark brown or bluish coating is noticed, then this is a sign of problems in the ventilation system. To confirm the diagnosis, you need to unscrew the oil filler cap, and then cover the hole with a sheet of clean cardboard.

Then the engine can be started and idling, raising the speed to 900-1100 rpm. If the cardboard is pressed tightly against the neck, then the ventilation system is working properly, that is, a vacuum is created in the crankcase. If this does not happen, then the nozzles and other elements of the system need to be cleaned, purged or replaced.

Oil is leaking from the gearbox

As mentioned above, the lubricant found during the inspection at the junction of the box and the motor can be both engine and transmission oil. To begin with, manual transmissions rarely leak in this area, since the oil in them is below the input shaft bearing. Such boxes are more likely to leak grease in the area of ​​\u200b\u200bthe gasket of the gearbox pan cover or from the breather.

Most often, oil leakage between the engine and the gearbox occurs on machines with automatic transmission. Oil in such boxes is supplied to mating parts not by spraying, but under pressure, which creates an oil pump. In other words, the pressure inside the automatic transmission is higher.

Often, oil from the automatic gearbox flows between the automatic transmission and the engine due to a faulty torque converter. As a rule, its malfunction occurs along with the failure of the oil pump. In this situation, an expensive repair or complete replacement of the automatic transmission is necessary.

We also note that in some cases, lubricant leakage is accompanied by foaming. The appearance of foam in the gear oil can occur both as a result of overfilling or a decrease in the level, and after filling in a lubricant that does not meet the tolerances and requirements. This is also true for the engine oil in the internal combustion engine. If the dipstick shows that the oil level in the engine or gearbox is above normal, then you need to remove the excess.

As for the automatic transmission, it is forbidden to add oil to such a box, which differs in properties from the previously filled one. In other words, you can't. To switch to other fluids, you must first or gearbox to remove the remnants of the old grease. After that, a complete one is produced in a box or engine.

Note that in many cases, even a serious repair of the automatic transmission may not bring the desired results, and the costs of such an operation will be quite high. For this reason, it is optimal to carry out a complete diagnosis of this unit, after which you can decide what will be more profitable, repair or replace the box with a contract or a new one.

Also, in the process of diagnosing automatic transmissions or other types of boxes, it should be borne in mind that oil leaks can occur for a number of reasons, which are quite easily and quickly eliminated. This means that it is not necessary to remove the box immediately.

For example, even a loosely inserted dipstick to check the oil level or an insufficiently tightened drain plug will cause a leak. Grease may also leak at the installation sites of various sensors. A common cause is insufficient tightening of the specified elements, damage to the sealing rings at their installation site, etc.

If grease leaks through the sensors, this indicates that the rubber seal is damaged, kinked, or has other defects. The sensor itself can also be destroyed. In this case, the device is replaced with a new one or only the sealing element is replaced (if possible).

The appearance of malfunctions or noises clearly indicates both breakdowns and problems with the lubricant (insufficient or high level, loss of properties, non-compliance of the lubricant with tolerances and requirements, etc.).

For example, if the box is buzzing in neutral gear, then the bearing on the drive shaft may fail or the gear oil level has dropped. If the problems are related to the synchronizer clutch or blocking element, then the noise in the box appears when driving in a certain gear (more often at high speed, 3 speed, 4, etc.).

A hum from the box may also appear when the gearbox mount is loosened. Insufficient clutch pedal depression or problems with this unit (especially on cars with a single-disk "robot" manual transmission) cause a crunch, jerks, jerks, and difficult switching. In this case, the parts experience increased loads, after which defects occur, oil appears at the junction of the box with the motor.

If the situation is emergency, that is, a lubricant leak appeared on the road and there is no way to put the car in for repairs, then many drivers try to stop the leak with the help of special additives. As a rule, softening sealants of the “stop-leak” type contain components that allow the sealing elements to return elasticity.

In other words, it is possible to restore the tightness between the shafts and the seals for some time. This allows you to get to the place of repair of the vehicle on your own. So, we strongly do not recommend using such solutions both in the engine and in the gearbox.

First of all, the additive does not remove the wear of parts, that is, the breakdown itself not only persists, but also progresses. Also, this method is not suitable for large leaks. Moreover, the additive has a serious effect on the lubricant and on the parts themselves inside the assembly. Otherwise, the addition of an additive worsens the basic properties of engine or transmission oil, clogs the engine and gearbox lubrication system.

A frequent result is that after disassembling the unit, into which such additives were previously poured, complete unrepairability or significant wear is found not only of the initially problematic, but also of other structural elements.

For this reason, it is better to choose the right lubricant for topping up and use it as needed than to buy sealants and additives. Also, auto mechanics and experienced drivers do not recommend switching to a thicker lubricant after detecting leaks, which is not recommended by the vehicle manufacturer or does not correspond to the operating conditions of the car.

The same can be said about special oil thickeners. Although this approach in some cases can reduce or eliminate leakage, however, the lubrication of mating loaded parts also deteriorates. As a result, the wear of engine or gearbox parts is greatly increased.

Summing up

A fairly common situation is that the driver may not notice the problem for a long time, especially if the oil seals, gaskets and seals do not flow, but “sweat”. In other words, the level of lubrication is reduced, but gradually. The danger is that the unit is still subject to wear, and sooner or later a strong leak may open. In this case, the gearbox or engine will be left without oil in a matter of minutes.

For this reason, it is important to pay attention to the appearance of noise and knocks in the engine and transmission. For gearboxes (especially automatic transmissions), it is also impossible to ignore difficult shifting, the appearance of jerks, shocks or delays when shifting gears. As for oil leaks, it’s not worth delaying repairs in this case.

Leaking grease not only pollutes the gearbox and internal combustion engine, but also gets on other elements in the engine compartment, having a negative impact on them. Also, you should always remember that a decrease in the level of lubrication in the engine or gearbox quickly leads to wear and further breakdowns of these units.

Have you ever noticed leaks in the engine compartment or noticed oil stains under the car? The appearance of such factors indicates serious malfunctions in the vehicle, which should not be ignored. Let's talk about why oil leaks between the engine and gearbox, and how to fix this problem.

• Peculiarities

  Lubricants poured into the engine compartment and transmission of a car, first of all, must provide structural parts with a reliable degree of protection against premature wear. But due to the fact that the operating conditions of these systems differ significantly, it is impossible to use a liquid with the same viscosity and chemical composition in both cases.

  Both lubricants - transmission and motor - are classified according to the international SAE system and can have mineral, semi-synthetic and synthetic bases. This is where their similarities probably end.

  The engine system of the car operates under conditions of high temperature and operational overloads. That is why she needs a climate-resistant liquid that prevents the formation of oxidative reactions inside the working area. In addition, it should wash out the particles of carbon deposits formed during the operation of the car from the engine compartment, making it easier for the details to “freedom in movement”. Engine fluid circulates under high pressure inside the system, so its viscosity should not be excessively high.

  As for the gearbox oil, excessive fluidity cannot take place here. It is applied to parts by spraying, is not subjected to critical overloads and does not require a large amount of additives.

  Such differences in the use of lubricants determine their useful life in a vehicle: for motor fluid it varies within 5-10 thousand kilometers, for transmission fluid - 60-80.

  Looking for reasons

  The viscosity of motor oils at a temperature of - 20 degrees

  An oil leak from a car engine or transmission can start immediately after you change it. The presence of smudges may indicate that the fresh fluid does not meet the requirements stated by the automaker. For example, instead of the usual thick mineral water, you decide to use liquid synthetics. If the car refuses to accept it, you will immediately know about it. This problem is easily eliminated - just pour oil with the required viscosity into the engine or transmission.

  If the lubricants used have the necessary parameters, and smudges are still visible on the engine or box, then the situation can be serious. The failure of one, even the smallest component, can break the tightness of the systems and cause oil starvation. That is why it is so important to fix the leak in a timely manner.

  The first step is to figure out which system the oil has left.

  Primary diagnosis begins with the study of the consistency, smell and color of the leaked liquid. Fuel and lubricants for gearboxes have a dark, sometimes reddish tint and a very pungent odor. The fluid is thick and does not absorb contaminants. Those. a drop of gear oil will be covered with a layer of dust, but it will not absorb it.

  As for motor lubricant, it will behave differently in relation to contaminants: it completely absorbs them. Fuels and lubricants for internal combustion engines have a more liquid base, a reddish-amber hue and a faint smell.

  If a visual inspection of smudges is difficult due to the design features of the car, then the problem can be solved using an oil dipstick. Measure the fluid level in the engine compartment, the deviation of this indicator from the norm will indicate a problem.

  

  Some modern cars have a dipstick to check the oil level in the box. But it will only allow you to identify the problem if the lubricant rapidly flows out of the gearbox. In these cases, dark spots of technical fluid can be recognized under the front of the car. Minor smudges at the lubrication level will not immediately affect, the dipstick will not be able to “notice” them.

  Lubricant is leaking from the engine

  If an inspection of the car and a study of the condition of the leaking fluid gave reason to believe that the problem lies in the engine compartment, then it is necessary to highlight the weakest points in the system through which oil could escape.

  Causes of failure:

  • Overflow of liquid. No matter how trite it may sound, oil can flow out due to its overflow into the oil compartment. If you filled in the grease "by eye" and did not check its level, a leak may form around the entire perimeter of the engine. Excess material circulating under high pressure in an internal combustion engine will simply be squeezed out of the working space and flow down the outer sides of the internal combustion engine. Fixing the problem is easy: unscrew the oil plug at the bottom of the motor and let the excess fluid exit the crankcase.
  • Wear, incorrect installation or destruction of the sealing elements. If the car has been idle for a long time, the oil seals and gaskets may have collapsed due to insufficient moisture. After starting the car, they cannot function normally (their elasticity is lost), and therefore the lubricant leaks out. The remedy in this case is to replace the problem parts with new ones; you can read about how to properly install the sealing parts in order to eliminate oil leakage in the engine on the Internet.
  • Insufficient crankcase ventilation. Excessive accumulation of exhaust gases in the crankcase of a vehicle can create additional pressure and force consumables out. This situation occurs when the channels of the ventilation system are clogged. An oil slinger valve will help diagnose such a problem. Check its condition. Did you see a gray or dark brown coating? So, the reason for the smudges lies precisely here. If the presence of plaque still raises doubts about insufficient crankcase ventilation, cover the opening of the open oil filler neck with a small sheet of white cardboard and start the car engine (it is recommended to keep 900-1100 rpm.). A tight fit of the cardboard to the oil filling hole indicates the normal operation of the ventilation system. Otherwise, it is necessary to clean or replace the internal combustion engine nozzles.
  • valve cover deformation. In rare cases, when car manufacturers use low-quality metal, a violation of the geometry of the valve cover may occur, which will be accompanied by large oil losses. Unfortunately, installing a new gasket will not solve the problem. The only possible option is to replace this very cover.

  "Escape" gear oil

  

  If the oil between the engine and the gearbox has an unpleasant pungent odor, it means that it is leaking from the vehicle's transmission system. Moreover, a similar problem occurs most often on “automatic machines”: in a mechanical box, the oil level is much lower than the input shaft bearing.

  The most likely cause of lubricant leaks from automatic transmissions is most often a malfunction of the torque converter and oil pump. And it is not possible to repair these units on your own: dismantling the elements is extremely time-consuming. To return the car to its former performance, a complete replacement of the “machine” or its expensive repair will be required.

  The most “harmless” disease of the gearbox for a motorist can be the banal wear of seals. By changing them, you can continue to operate the car as usual. Improper installation of the oil dipstick (if equipped) can also cause loss of lubricant.

  If you notice that one of the two systems of the car is leaking, but you could not recognize exactly where the oil comes from, then service center specialists will help you deal with problems in the engine or gearbox. The main thing - do not postpone the decision for later. Oil starvation can lead to a complete loss of vehicle performance.

  Measures to prevent oil leaks

  It is impossible to completely protect your car from problems, but you can significantly reduce the likelihood of their occurrence. To do this, just follow a few simple rules:

  

  • Constantly check the level of the lubricant composition with a special dipstick. Get in the habit of checking the amount of engine oil every 5-6 days. Such a measure will allow you to recognize the presence of a problem before it becomes critical. Yes, all modern cars have a special sensor that informs the driver in case of oil leakage from the engine. But it is activated only when more than 300-500 ml is gone.
  • Perform regular vehicle maintenance. So you can timely notice the damaged element of the system and replace it with a new one. In addition, regular oil changes will prevent the formation of carbon deposits and sludge deposits, and increase the degree of protection of motor elements from excessive wear.
  • Only buy products recommended by your vehicle manufacturer. The vehicle owner's manual contains information on the recommended viscosity of engine oil. Compliance with these requirements will allow you to extend the life of the propulsion system. When choosing an oily liquid, pay attention to the design of the product and the quality of its capacity, so as not to run into a fake. When it comes to choosing a brand, you should rely on your intuition. Many companies have a good reputation in the world market, but it is impossible to say unequivocally which oil is better - after all, each vehicle has its own requirements for fuel and lubricants.
  • Do not put the engine under load unless it has been properly warmed up. Started the car in the cold and immediately decided to drive it? Then stock up on plenty of engine oil for regular top-ups. Thickened fluid in a cold system circulates unevenly, so pressing the gas pedal can cause it to be squeezed out of the system; in order not to squeeze out the oil, it is recommended to warm up the engine for - 10-15 minutes.
  • Purchase only original spare parts. If you have found the reason why oil is flowing from the engine or gearbox, immediately start car repairs. But when choosing new parts for the system, try to give preference to original parts. Their quality (as well as the price) is much higher than that of the “Chinese” counterparts, which means that they will be able to serve your motor longer. By the way, non-original spare parts may differ from the original dimensions, which in turn will affect the tightness of the structure.
  • If it is not possible to carry out maintenance of the vehicle on your own, entrust the work to professionals. And not to “garage masters”, but to service centers specializing in vehicle maintenance.

  What should be remembered?

  Mixing liquids of different manufacturers and viscosity characteristics can cause undesirable consequences: if the oil has leaked out on the go, and there is nothing to add it with, you can no longer operate the car. Call a tow truck and take the car to the nearest service station. Adding oil of a different composition - transmission or motor - is not allowed due to the fact that a destructive chemical reaction can begin inside the installation, which in turn will lead to even greater consequences. Of course, if fluid loss occurred on the highway, the driver can fill the system with oil at hand, but only in order to get to the experts. In the future, the oil “compote” will have to be drained, and the installation into which it was poured should be thoroughly rinsed.

Every driver who takes care of his car develops a useful habit over time: before you go on a trip, you need to check for any traces of oil or antifreeze leaks under the car. A good solution would be the following method - in the evening, before parking the car, lay a clean cardboard box under the engine and box (for example, from a box) and then in the morning you can more accurately localize the problem.

If you see something suspicious, then try to find the cause of the oil leak between the gearbox and the engine and fix it - at a specialized service station or on your own. One common oil leak is at the connection between the gearbox and the engine. Well, if you keep the engine compartment clean, then it will be easier to find the cause of the loss of lubricant. Otherwise, before the diagnosis, you will have to wash everything clean in order to accurately localize the leak.

Features of the lubrication system of the engine and gearbox

Lubrication of the engine and gearbox is carried out with oils with different chemical composition. An experienced driver or mechanic will be able to immediately, by smell or color, determine which assembly is losing lubrication. The engine is equipped with a forced oil supply system to rubbing units and assemblies.

In a manual gearbox, oil enters the friction points with the help of "splashing" from rotating parts. In automatic transmissions, the oil is supplied by an oil pump. In a manual transmission, oil leakage with the machine at a standstill is rare. The design feature is such that the oil level is less than the bearing on the input shaft. Therefore, on this type of gearbox, losses occur during movement.

The oil change periods for these units are different: engine oil is changed every 8-15 thousand kilometers, and transmission oil is replaced after 50-70 thousand.

The amount of oil poured into the engine or transmission must comply with the manufacturer's standards. With oil starvation, rubbing parts wear out faster and their service life is significantly reduced.

If the oil is poured in excess, then a banal extrusion of excess through weak points is possible. It is necessary to monitor the level of lubricating fluids constantly. Get into the habit - before you start the car, check the oil level in the engine, gearbox, coolant expansion tank, brake fluid amount. Timely treatment will be much cheaper than serious repairs.

Possible causes of oil leakage between the gearbox and the engine

As soon as you notice the first signs of an oil leak, you must immediately look for the location of the breakdown. It is impossible to delay the solution of this problem. You do not want to stand somewhere in the middle of the field and return home on a tow truck? The most convenient way to determine the place of oil leakage between the box and the engine is on a lift or pit. Drops of liquid are definitely a flaw and you need to get rid of it.

It is unlikely that it will be possible to instantly identify a broken unit - the lack of direct access to vulnerable nodes makes this difficult task difficult. Most often, the problem is in the gearbox and, most likely, to accurately diagnose and fix the problem, you will have to dismantle it.

Each car has its own characteristics, but there are some general principles for diagnosing and repairing breakdowns. First of all, you need to decide what type of oil is leaking - oil from the engine or from the gearbox? This can be determined by the smell and type of pollution. The size of the stain can determine the severity of the problem and the amount of oil lost.

In cars with mileage, the main oil seal of the engine first begins to leak. The increased axial movement of the crankshaft causes the oil seal to be squeezed out and leakage occurs. The worn oil-resistant rubber of the stuffing box can no longer contain the oil, which has warmed up to a fluid state. When the crankcase ventilation system is clogged, the pressure in the system rises, and excess oil escapes through weak points.

The transmission also has its own ventilation system: through a special breather, the expanded hot air exits the system. If it is clogged, then excess pressure is created and the oil is also squeezed out. There is only one option for eliminating a seal leak - replacement. And if you change one of the seals, it is better to immediately replace the second one so as not to remove the box twice. Immediately it is worth checking the shaft play, the condition of its seat, bearing wear.

Causes of oil leakage that can be eliminated without removing the box:

• the drain nut is loosely tightened;
• loose installation of the measuring probe (if it is provided in the transmission design);
• bad sensors.

If it didn’t work out with “little blood” and the oil continues to flow between the gearbox and the engine, get ready for a more serious and costly repair. By the way, count with the master - maybe replacing the box will be cheaper than its serious repair.

Reasons for dismantling the box from the car:

1. violation of the tightness of gaskets or seals;
2. wear of the main oil seal;
3. wear of the oil seal of the input shaft of the box;
4. improper installation of seals;
5. violation of the geometry of the pallet - a hit or bent pallet tears the gasket;
6. a clogged crankcase ventilation system can build up overpressure and squeeze out oil;
7. wear of the shafts that connect the engine and box;
8. play of the gearbox input shaft;
9. breakdown of the torque converter or oil supply pump on automatic transmissions.

Oil additives

Some drivers, seeing an oil leak between the box and the engine, immediately go to the auto chemical store for a magic one. Additives contain special substances that restore the elasticity of seals. This property ensures the restoration of tight contact between the stuffing box and the shafts and oil leakage can be eliminated for a while. Yes, the additive can help, but only for a while and only with a slight flow of the system.

The wear of the part will not go away, and therefore the breakdown remains, and the chance of getting into a more expensive repair or replacement of the unit increases significantly. The use of oil thickeners is not recommended. They can eliminate leaks, but at the same time worsen the lubrication of the nodes, which is fraught with increased wear on the motor or gearbox. If you still decide to use an additive, choose a softening sealant.

Let's summarize:

• traces of oil on the floor of the garage - a mandatory reason for inspecting the engine, box and joints;
• the weak point of used cars is oil seals, most likely, their service life has come to an end;
• be sure to check the ventilation system of the engine and box;
• the additive will not help - most likely, you will have to treat your car more seriously.

Any car uses oil. And it doesn’t matter if it’s a diesel or gasoline car, automatic or manual. Often, with prolonged use, the oil loses its level. It can not only enter the combustion chamber, but also leak at the sealing points. And the engine oil doesn't always leak. Transmission is also not immune from this. What to do if oil flows between the engine and gearbox? In today's article, we will look at this issue in detail.

How engine and transmission components are lubricated

The engine and gearbox use different types of oils. In the latter case, it is more viscous. Unlike a manual transmission, the engine and automatic transmission are lubricated by forced fluid supply. This function is performed by the pump.

As for the mechanical box, here the oil enters the teeth by spraying. The gear, located in the transmission case, scoops up the fluid, and thus the teeth are lubricated at the point of contact. Another feature is the oil change schedule. For internal combustion engines, it is 8-10 thousand kilometers, and for automatic transmissions - 70 thousand. As for the mechanics, on most machines it is maintenance-free. That is, oil is poured for the entire period of operation. But this does not mean that you can not check the level of its balance. If the gearbox is leaking, it can cause increased gear wear. Eventually, she will fail. When replacing, you do not need to pour above the norm. Excess liquid will simply flow out of the “weak” places.

Engine or gearbox?

If oil flows between the engine and the gearbox, you need to determine from which node it disappears. If it is a thick fluid, then it is transmission fluid, and the problem is in the gearbox. If the car is more than 10 years old, it should be checked. Due to wear and constant vibrations, it is squeezed out and leaks oil. You can also crankcase. To do this, you can bring a piece of paper to a previously removed pipe. If at engine speeds over 1 thousand it does not bend, the system is clogged. In this case, there is an increased pressure in the engine lubrication system and the liquid begins to flow, as they say, from all the cracks. The weak point is the junction with the gearbox. The transmission also has its own ventilation.

It is carried out through the breather. If it is clogged, the pressure level inside increases, and an oil leak occurs between the engine box. VAZ-2110 is no exception. The solution is to clean the ventilation ducts and replace the stuffing box. When installing the latter, it is recommended to install the second one, regardless of the state, since its resource is also limited.

Banal reasons

Why is oil leaking in the box? The reasons may be trivial.

This is a loose drain plug or unscrewed sensors. Sometimes a leak occurs due to a loose dipstick. Here, leaks can be seen without dismantling the box and repaired on site. But what to do if these parts are tight, but oil still flows between the engine and the box? Let's consider further.

Serious malfunctions

There are a number of reasons for an oil leak that require the dismantling of the box. The first is the breakdown of gaskets and other sealing elements. It could also be a seal. But if in the case of the engine it is the crankshaft, then the sealing element of the input shaft flows in the transmission. Why is oil still flowing between the engine and gearbox? This problem occurs when the pallet geometry is violated. This often happens when hitting a large hole or other obstacle.

As a result, the pallet hits the box and deforms. If this is an automatic transmission, the reason is the breakdown of the "donut" ( torque converter) or in a faulty oil pump. The box itself goes into emergency mode. The car only works in 3rd gear.

About additives

Now in the automotive world there are many additives. And some car owners, deciding how to fix oil leaks, run to stores for a “miraculous” additive. They pour it into the engine or box (and most often both there and there) and wait for the effect. But as practice shows, it does not give any results. The additive is not able to eliminate mechanical damage to the pallet, “glue” the torn gasket and restore the squeezed out oil seal. The problem does not leave the car owner. The only thing that can reduce the effect of a leak is oil thickeners. Thus, you intentionally change its characteristics.

But this is very harmful to the engine and gearbox, and leaks will not be 100 percent eliminated. Therefore, it is necessary to repair the manual transmission, change the seals and gaskets. Feedback from car owners does not confirm the effectiveness of the additives.

How does the rear seal change?

This procedure is quite complicated, since the element is located behind the clutch system. If this is removed the driveshaft. Further, as on front-wheel drive, there is a box, a clutch assembly with a basket and discs, as well as an engine flywheel. The rear oil seal itself is installed in the housing and secured with eight bolts. After unscrewing them, we take out the case and press in a new element. If you have difficulty installing it, you can use a rubber mallet or an ordinary steel one, using a soft gasket. The latter can be made from a piece of an old car camera. Further, all the elements are assembled in the reverse order.

Front

It is much easier to change than the rear one. The element is located at the end of the crankshaft (on vehicles with a transverse engine - near the right pillar). To replace, we need to remove the timing belt cover and put the piston of the first cylinder at TDC. We loosen the tensioners and remove the timing belt, as well as the generator, after removing the pulley. Drain the engine oil. Dismantle the crankshaft pulley. Unscrew the oil pump. An oil seal will be pressed inside it. You can remove it with a minus screwdriver. The new one is pressed in using a large head (27 and above) or on a special machine. Further assembly is in reverse order.

About the selection of oil seals for gearboxes

When buying, you need to consider what kind of oil you will pour into the box in the future.

There are oil seals with different elasticity - for mineral and synthetic products. If you pour the wrong oil into a box, such an element will begin to crack. Usually this happens with "synthetics". It has good flushing properties. Note that for automatic transmissions there is a separate range of oils with a certain viscosity. Their properties differ significantly from manual transmission fluids.

Keep your engine clean

After replacing all the elements, it is necessary to carry out an external engine wash. So you eliminate the old places of oil leakage and you will know from which places it will flow in the event of a malfunction. It is advisable to wash the motor and gearbox once every two years. Don't be afraid to point the jet of water at the engine. The only thing is to ensure the tightness of the ignition elements. This is a coil, distributor, candles, and the ingress of moisture on them is highly undesirable.

Summary

Thus, if a leak occurs between the box and the engine, you should not postpone repairs. Whether it's manual or automatic, it doesn't matter. Driving with low oil equally kills these boxes, not to mention the engine itself. Well, to control the level daily, crawling under the bottom and taking out the dipstick (if it is a box) is just madness. With a one-time financial investment in repairs, you will forget about the leak for several years. And remember that by using oil thickeners you are not solving the problem, but just hiding it.

Keep an eye on the car for leaks when it is parked. The presence of oily drops under the bottom is the first sign that you have oil flowing between the engine and gearbox.

When such a problem is detected on a car, drivers begin to be interested in the question of why oil is leaking between the box and the engine. The fact that such a phenomenon is unacceptable to ensure the performance of these units is known to almost all car owners. However, why this happens, where the malfunction is, what to do in this case, is unknown to many drivers.

There can be many reasons for this phenomenon, so finding and eliminating them must be taken seriously.

Oil leakage between the gearbox and the engine is a serious problem, both for the car and for its owner. The search for and elimination of such a phenomenon should not be postponed so as not to further complicate the problem. In such cases, they act differently, who takes the car for repair to specialists, and some owners find the cause and eliminate it on their own. Let's talk about this in more detail.

About the features of the lubrication of these units

Lubrication of engine and gearbox components, both mechanical and automatic, is carried out with lubricating fluids with different chemical compositions. This is due to the operating conditions of these nodes, the features of their design. Internal combustion engines have a forced system for supplying engine oil to rubbing pairs. In mechanical gearboxes, friction points are lubricated by spraying the “transmission” from rotating parts.

Lubricating fluids differ not only in chemical composition, but also in the additives used, viscosity and other technical characteristics. Replacing them is also somewhat different. If engine oil is replaced on average after 10-15 thousand kilometers of a car, then for transmission oils it is several times more, and is approximately 60-70 thousand kilometers. The terms of use of oils depend on their origin. Mineral oils serve a slightly shorter period than.

Sometimes in the practice of repairmen, and even car owners, there are cases when, after draining the mineral oil, flushing the system and filling in synthetics or semi-synthetics, leaks are detected. This perplexes the owners, why was everything normal on the old fluid, but now it is leaking? This can only be explained by the fact that these oils have a greater fluidity compared to mineral water.

Why do leaks happen?

As a rule, a leak at the junction of the engine and gearbox is caused by a malfunction of one of the named units, very rarely, but sometimes both nodes have problems at the same time. They notice the appearance of such a problem by the appearance of an oil stain under the bottom of the car. In this case, you must immediately check the level of lubrication in the crankcase. In some cases, this can tell you where the leak came from.

By the size of the oil stain, one can judge the amount of lost lubricant. There is a problem, it needs to be solved. First of all, you need to try to determine what kind of fluid can flow out, motor or transmission. Experienced mechanics and drivers determine this by the smell of liquids, they are very different. If this worked out, you can begin to analyze the possible causes of leaks.

High vehicle mileage can cause lubricant to pass through the crankshaft rear oil seal. Worn thrust half-rings of the crankshaft lead to an increase in the free axial movement of the shaft, which leads to the extrusion of the oil seal and the appearance of a leak. The worn edges of oil-resistant rubber will also not be able to hold the lubricant heated during engine operation.

This can be facilitated by the presence of a large amount of crankcase gases, which also contributes to the expulsion of the lubricant. An increase in their number in the crankcase may occur due to contamination of the system for removing them from the system, or through wear of the cylinder-piston group. If in the first case it is enough to flush the crankcase exhaust system, then in the second case it will be necessary to overhaul the engine.

Leaks in the area of ​​\u200b\u200bthe rear oil seal of the crankshaft of the engine, in addition to reducing the level of lubricant in the sump, have other negative aspects. If it comes into contact with a rotating flywheel, grease can get on the clutch parts. This will lead to its slipping and the inability to continue further movement.

About problems in the automatic transmission

Sometimes grease can also leak from the gearbox. In mechanical boxes, this phenomenon practically does not occur, since the level is below the input shaft bearing. But in automatic transmissions, this can happen. In such units, lubrication is supplied by an oil pump, so there is pressure in the lubrication system. Most often the culprit of this problem, which often fails at the same time as the pump.

Eliminating such a problem for the owner can fly into a solid financial expense. In some cases, it is easier to buy a new automatic transmission than to repair it. We tried to convey to everyone why there may be an oil leak between the gearbox and the engine. We hope that this article will bring real help to someone in identifying and eliminating such problems. After reading it to the end, carefully weigh your repair options, and only then make a decision.