Why the engine eats oil: possible causes

2024 Author: Erin Ralphs | [email protected]. Last modified: 2024-02-19 11:42

Sooner or later, car owners are faced with increased oil consumption in the engine. There are many reasons for this increased "appetite". It must be said right away that for many modern cars, some consumption is still typical. But if it is too large, you should start diagnosing the motor. Consider typical reasons why an engine eats oil.

Main causes of increased consumption

As already noted, there is an allowable consumption - this is oil for waste. Simply put, regardless of the type of internal combustion engine, a small part of the lubricant is burned in it during operation. The fact is that the lubricating fluid circulates in the system and enters every element of the motor, including the cylinder walls.

Each piston is equipped with special rings that collect lubricant residues from the walls of the combustion chamber into the crankcase. However, a small part still remains on the cylinder walls and burns together.with a mixture of gasoline and air. So, the cost of the lubricating fluid should be from 0.05% to 0.25% of the volume of burned fuel. For example, if the motor used 100 hp. gasoline, then the allowable consumption of lubricants should be no more than 25 g. However, this is the maximum figure. The minimum consumption is up to 5 g. This is all an acceptable limit. If deviations are observed, then it is worth considering why the diesel engine eats oil.

On new units, lubricating fluid may not be consumed at all. But this happens when the engine is completely new. As the main mechanisms wear out, this figure will increase. If the expense is frightening, you should look for the cause. And in order to eliminate it, you have to disassemble the entire motor. Also, the cause may be simple, which is easy to fix. Next - about the main malfunctions that lead to increased consumption of lubricant.

Strong wear of oil scraper rings

On the pistons of any internal combustion engine there are special oil scraper rings - one for each piston. They, as already noted, are needed to protect the cylinders from the ingress of lubricants into them. Since the rings are in close contact with the walls of the combustion chamber, and at the same time it is associated with constant friction, they tend to wear out. If there is wear, then the gaps through which lubricating fluids will enter the combustion chamber will increase. There, the lubricant will safely burn out along with the fuel mixture, and then exit into the exhaust system in the form of smoke. This is the answer to the question why the engine eats oil and smokes.

Also in case of strong overheating of the engine, the rings can lie - they lose their elasticity and are pressed against the pistons in their seats. Diagnose the problem by the characteristic blue smoke from the exhaust pipe. You can fix the breakdown by replacing these same rings.

Worn cylinder walls

This is another popular reason why engine oil eats a lot. Here it freely in large volumes enters the combustion chambers through the gaps, where it burns out. You can also diagnose by smoke. To eliminate the breakdown, a major overhaul with boring of the cylinder block is necessary. But there is an alternative solution to the issue - to purchase a new block. But this is a more expensive option.

Leak through valve stem seals

The valve stem seal is a special seal in the engine. It is made of special materials that can easily withstand high temperatures. Due to severe wear, the oil seal loses its elasticity characteristics. The result is leakage and high consumption of lubricant.

To replace the caps, you only need to dismantle the cylinder head. It is not necessary to disassemble the entire engine. This is the least expensive reason why an engine eats oil. Subaru engines often suffer from this problem. Many owners of these cars complain about high consumption. Some write that this is normal and these engines actually have such a design (opposite). However, a common reason whyengine oil on Subaru ej20 - these are valve stem seals.

Cylinder head gasket leaks

Such a defect is most often seen on used cars. On new ones, this does not happen at all - under production conditions, the bolts are tightened very well. On machines with high mileage, where engine wear is already high enough, the gasket simply burns out. It happens quite often.

The gasket needs to be replaced to fix the problem. To do this, simply remove the cylinder head. After a new one is installed, it is recommended to evenly tighten the bolts so that the leak does not form again.

Crankshaft oil seals

In case of severe wear, low temperatures or low-quality oils being poured into the engine, the seals are often squeezed out, which causes high consumption. The cost of a new oil seal is minimal, but the amount of work to replace it is very large.

Turbine rotor on supercharged engines

If the car is equipped with a turbocharger, then leaks can increase significantly. It is possible to dry out the oil system in a very short period if wear is observed on the bushing on the turbine rotor. When the motor began to work differently, the first thing to do is to check the correct functioning of the rotor.

Frequent faults

Grease is leaking through the oil filter. One of the characteristic signs is smudges and stains under the car after parking. The cause of the leak is a loose tightening of the filter housing. You can easily get out of this situation - just tighten the filter more tightly. This will fix the leak instantly.

Also, motorists are faced with a leak through the cylinder head cover. In most car models, it is fixed on 6-12 bolts. Some of them may simply not be enough. Low quality oils also lead to increased consumption. The fact is that when lubricants get on the piston, they instantly burn out. It is recommended to fill in a better product and then the flow rate will return to normal.

Riding style

Not everyone drives quietly. With more aggressive driving styles, when the engine revs up to cutoff, do not forget that this is an extreme mode and increased oil consumption. In that case, it's business as usual.

Seasonality

The season also affects consumption.

So, in winter, consumption is higher, as the car works in severe frosts. Professional auto mechanics recommend using higher quality oils with a lower viscosity for harsh winters - then everything will be in order with consumption.

Diesel engines

We looked at gasoline engines, and now we will analyze why a diesel engine eats oil. High consumption if 1 liter of lubricants is consumed per 10,000 km. The causes of oil consumption in diesel engines are generally the same as in the case of gasoline engines. Grease can leak through the crankshaft oil seal. Also, leaks go through the cylinder head gasket or oil seals. It is recommended to check the injection pump. In 25% of suchcases, the problem lies precisely in it. HPF failures are different. In one case, you can get by with repairs, in the other, you will need a replacement. Among the reasons why the engine on KamAZ eats oil, one can single out long idling. Leaks through the turbocharger lubrication system are also often observed - to eliminate them, tighten the connections in the turbocharger system or change the gaskets. A clogged air cleaner and air intake lead to high consumption. This can be easily fixed by cleaning it.

Opposed motor

Designs of modern boxer engines are such that even in new condition they will consume more lubricants than their conventional counterparts. Manufacturers themselves, such as Subaru, claim that the normal consumption for a boxer engine is 1 liter per 2000-2500 km. Among the reasons why a boxer engine eats oil, there may also be rings, caps, leaks. Need engine diagnostics.

Increased appetite after overhaul

It also happens that a completely overhauled engine does not please its owner. To understand the reasons, it is necessary to understand what kind of repair was done. It is possible that the pistons did not change, but only the rings were replaced - they will take a long time to run in to oval pistons.

In fact, there are a lot of reasons why an engine eats oil after an overhaul. And in order to find a malfunction, it is best to disassemble the motor and inspect it. But this is only recommendedprofessionals.

Conclusion

We looked at the main reasons why an engine eats oil. This information should help novice car enthusiasts in diagnosing their cars.