The pressure in the cylinders of an internal combustion engine is one of the main parameters of its normal operation. With low compression, the engine will be unstable. Lack of pressure in one or more cylinders can cause serious problems in the future. Let's look at a situation where there is no compression in one cylinder.
Does a lack of pressure always indicate a malfunction?
Before considering the main causes and signs of this phenomenon, we will understand how this parameter affects the overall performance of the engine. If the pressure in the internal combustion engine lubrication system is lower than the norm calculated by the manufacturer, then practice shows that the components of the internal combustion engine will be excessively worn. But if we talk about compression, then this is not always the case. When the rings on the pistons are paired with the cylinders, the lubricant is very important - it is collected on the cylinder walls. Due to the oil, the gaps between the rings and cylinders are sealed.
When not the entire volume of the combustible mixture burns in the cylinders, this will lead to high fuel consumption. If one or more spark plugs is out of order, the gasoline entering the combustion chamber will flush the oil from the cylinder walls. This fuel is an excellent solvent. If there is no lubricant in the cylinder, if there is no pressure in the lubrication system, then the oil will no longer be able to sufficiently seal the gaps in the cylinder. Therefore, air under high pressure and gases generated during the combustion of the air-fuel mixture will enter the crankcase. This will lead to the fact that in a 4-, 6-, and also an 8-cylinder engine, the compression will sharply decrease, and then completely drop.
If the compression is even higher than necessary, this will also cause increased oil consumption. Due to the high oil compression, wear of the rings will occur more intensively. The gaps that inevitably form during the operation of the engine are perfectly sealed with a lot of grease. In this case, urgent repairs are needed. However, in fact, compression will not show this problem.
Signs of a problem or lack thereof
If there is no compression in one cylinder or in several, then this can be determined by the following symptoms:
- A reduced pressure will be reported by a difficult engine start. A motorist trying to start will turn the flywheel with a starter much longer than usual. If the pressure disappears completely, then the start will be almost impossible.
- An engine with low compression in one of the cylinders will be troit, work with less stability. Since there is no compression in one cylinder, the engine speed and idle will be unstable. This will be displayed on the dynamics of acceleration.
- Necessarily in such an engine there will be increased fuel consumption. Determining this symptom is difficult enough for those who do not follow this indicator. But for those who know the expense for a certain mileage, the increase in engine appetites will be immediately noticeable.
- Malfunctions in the operation of the combustion chambers will certainly occur. When moving uphill, hydraulic lifters may begin to knock. Especially it will be clearly visible and audible when driving at low speeds.
- In diesel power units, it is possible to determine that there is no compression in one cylinder, according to characteristic pops.
- Sometimes pressure can increase in the lines where the coolant circulates. Antifreeze due to low compression will squeeze out from under the gaskets, from under the nozzles and other seals.
- With poor compression (if it is due to a broken cylinder head gasket), the system is leakproof. If you open the hood, you will see the exhaust gases passing through the gap in the gasket. This malfunction leads to the occurrence of rings on the pistons, which will contribute to increased oil and fuel consumption. In some cars, this symptom may be accompanied by an increase in power and the formation of white smoke from the exhaust pipe.
How long can the engine work?
Low or no compression in the engine is a common problem that motorists face. If the pressure has decreased slightly, then the engine may well be operated for a long time. However, too low a pressure can occur due to severe overheating of the engine. Below we will try to find out why there is no compression in one cylinder. Consider the mechanical and non-mechanical causes.
Non-mechanical damage
At first, it is worthwhile to deal with non-mechanical causes that led to the lack of compression in an automobile internal combustion engine.
This may include various errors that the mechanic could make during the repair and assembly of the unit. If the motorist independently or specialists at the service station incorrectly set the timing marks or the gas distribution phases (and this often happens due to inattention), then the valves will not close when the principle of the internal combustion engine requires it. During the compression stroke, the valves do not have time to close completely, because the phases are knocked down. As a result, some of the air will simply come out.
Sometimes problems of compression of a non-mechanical nature may be due to coking of the piston rings. This problem can subsequently lead to sticking of the valves in the grooves. Gases will pass easily as there are no seals.
In this case, if there is no compression in the 1st cylinder or any other, the oil scraper ring on the piston will not be able to fulfill its function, and the lubricant will also not be able to fill the gaps - it will be washed off the cylinder wall with unburned gasoline.
Mechanical problems
If a 4-cylinder or larger power unit works, but there is no compression, then the reasons may be in the mechanics. Suddenly, compression disappears for one of the following reasons:
- Most often, exhaust valves are damaged. Cracks can often be observed on the valve. This is due to natural engine wear. The valve does not fit enough on the seat in the cylinder head. That is why there is no compression in the 2nd cylinder.
- Also one of the reasons is valve seat wear. Decreased or lack of compression due to mechanical damage. Often the saddle is pressed through.
- A popular reason is a burnt gasket between the engine block and the head. Experts are sure that this is an inevitable situation, which appears due to the high mileage of the car. A little less often, the cause of burnout gaskets is getting dirt on a plane. This problem is encountered when the engine is used for a long time at elevated temperatures. The cylinder head is cracking, the block is deformed.
- The mechanical causes of low compression include scoring in combustion chambers. There are many reasons for the formation of scoring, but the most common is overheating. If the piston ring breaks inside the cylinder, this results in scuffing. Damage to the parts of the CPG also lead to a decrease in compression. For example, the inter-ring jumpers on the pistons often break.
- If the timing belt breaks, then there will be no pressure in all cylinders and the engine will not start.
- Intake valves fail. Cracks form on the pistons or on the walls of the cylinders. Carbon deposits appear on valve seals and rings. All this helps to reduce compression.
A sharp drop in compression can lead to very serious malfunctions in the power unit. If there is no pressure in one of the cylinders, then a diagnosis must be made. Next, consider how to check compression in the cylinders.
Measurement rules
The engine immediately before measurements is untwisted by the starter to the maximum possible speed. To do this, open the hood and remove the wires from the spark plugs. The candles themselves are twisted. This will remove the resistance to rotation of the flywheel by the starter. The engine must be warm before measuring. Before measurements, turn off the fuel supply so that gasoline does not wash off the oil from the cylinder walls. The battery must be charged so that the starter can rotate the flywheel normally.
Cooking tool
To check which compression is in the cylinders, you need a compressometer. This is a pressure gauge with an extension and an adapter for screwing into spark plug wells. Compressometers may vary. They are different for gasoline and diesel engines.
Open the hood, disconnect the spark plug wires, remove the candles. Then prepare the compressor for work. Adapters of appropriate sizes are connected to the device and screw the adapter into the candle socket. Then the driver sits in his place, presses the gas pedal fully and rotates the engine with the starter. After rotation, you need to look at the measurement result. Previously, you should find out in the instructions for the car, what should be the compression in the cylinder - for most gasoline engines, the value should be around 12. A check is performed in each cylinder.
Oil compression
If there is no pressure, then this is either a problem with the cylinder head, or a malfunction or normal wear of the CPG. To identify which of these two factors is the cause, you need to add oil to the combustion chamber.
If there is no compression in the 3rd cylinder or in any other, then a little oil is poured into the cylinder before measuring with a compressor. Enough 50 grams. If the compression after the bay has increased, then the problem is in the rings. If the pressure has not changed, then the problem is in the cylinder head. Both in the first and in the second case, it will be necessary to disassemble the engine for repair.
How to increase compression?
If there is no compression in the 4th cylinder, you can try to raise it. To do this, ring the rings. You can apply Dimexidum, Laurel and other products available on the market. But this is not a panacea, and this will not allow to avoid repair. This measure is only temporary.
