Stuck piston rings. Symptoms and solutions

The general symptoms of stuck piston rings are a decrease in compression ratio and an increase in fuel and engine oil consumption. Also, the engine starts poorly, and drivers note a drop in the car’s dynamic capabilities. There are several methods for dealing with this problem.

Why are piston rings stuck?

There are rectangular grooves in the piston’s body, in which steel rings are installed, that prevent the gases breakthrough from the combustion chamber into the engine crankcase. 

The combustion products of fuel and oil contaminate the channels and impede the ring’s mobility, which leads to a drop in compression and disruption of the normal engine operation.

The number of deposits will increases if the car is used regularly on short distances without warming up the engine properly or using low-quality oil that does not have the necessary properties or does not meet the requirements of the car manufacturer.

Also, the piston rings can get stuck if the car sat for a long time without being driven.

piston with rings

Symptoms of stuck piston rings

  • Problems when starting the engine, regardless of the ambient temperature, the car has a bad start;
  • Increased fuel consumption while maintaining standard operating conditions;
  • Increased engine oil consumption with the appearance of gray smoke from the exhaust;
  • The check engine light will be present on the dashboard;
  • A decrease in power and torque, which negatively affects the car dynamics;
  • A decrease in the compression value due to increased gaps;

What are the consequences of stuck piston rings?

If you continue to drive like this, the following major problems will appear:

  • An increased amount of carbon deposits due to burnt oil;
  • Misfiring due to insufficient compression and grease on the spark plug electrodes;
  • The piston will overheat, leading to small fragments of metal in the oil system;
  • The engine oil will lose its properties due to the penetration of combustion products into the crankcase;
  • Damage to the cylinder because of solid carbon particles falling under the rings.

When these first signs are spotted, preventive maintenance using chemical substances should be carried out. The materials dissolve or soften carbon deposits that enter the engine crankcase and are partially captured by the filter. In case of heavy contamination, it will be necessary to disassemble the engine for mechanical cleaning.

How to unstick piston rings?

Mechanical decarbonization

The procedure implies partial or complete engine removal. After draining the oil and antifreeze, it is necessary to dismantle the crankcase and the cylinder block head, and then unscrew the bolts of the connecting rod journals. 

The removed pistons are washed with an organic solvent using a soft brush. These special substances remove carbon deposits from the grooves and restore the mobility of the rings. Special cloth wipes are also used to better clean small particles of deposits.

After cleaning, it is necessary to assemble the motor. The procedure requires skills and special tools, thus cleaning should be carried out at specialized repair shops, but it will also provide the best result.

Dismantling, cleaning, and reassembling the engine back could cause other unwelcomed problems, that’s why it should be done properly.

Cleaning carbon deposits using additives

Another way to remove carbon deposits from the pistons is by adding additives to fuel or engine oil. The active substances dissolve deposits that burn out or are washed into the crankcase and captured by the filter. 

These additives are introduced into the tank during refueling or added into the crankcase during the next revision. 

There are a lot of good additives that remove carbon deposits and don’t cause damage to rubber parts. However, the drawback of these additives is that they may not work as expected.

Chemical cleaning

Chemical cleaning involves pouring a special solution into the cylinders of a heated engine that removes dense carbon deposits. Buildups are removed at the exhaust and partially captured by the oil filter. 

The disadvantages of this technique include the impossibility of controlling the quality of cleaning, and aggressive chemical cleaners can destroy rubber seals, which leads to oil leakage.

This is done by warming up the engine to the operating temperature, adding the chemical into each cylinder according to the instructions, and using a rubber bulb or syringe with an extension tube for refueling.

You can mix it up with kerosene and acetone in equal proportions, the processing time is 6-8 hours due to the low detergent properties.

The crankshaft should be periodically rotated in both directions to ensure the destruction of deposits and deep penetration of the reagent into the plaque.

After removing the chemical cleaner and installing the spark plugs, the engine is started and left idle for about an hour.

After the signs of stuck piston rings have disappeared, the engine is stopped and the oil along with the oil filter is replaced with a high-quality one recommended by the car manufacturer.

How to prevent piston rings from sticking?

The procedure is simple and should be carried out at least once a month. You will only have to drive at least 50 km or 30 miles, the RPM should be at least 3500-4000 rpm for 1-2 minutes. 

Intensive gas exchange and high temperature in the combustion chamber destroy the layer of deposits, particles are burned out or thrown out from the exhaust. Try to avoid driving at low air temperatures without warming up the engine properly.

Manufacturers indicate the type and viscosity of the engine oil, violation of the requirements leads to the formation of deposits and causes the engine to run poorly. Compliance with the maintenance schedule reduces the risk of carbon deposits. 

When carrying out maintenance, the condition of the piston group should be assessed with an endoscope, and the spark plugs should be changed promptly. 

On cars with electronic control units (ECU), it is recommended to read the errors stored in the memory, this allows you to identify engine faults.

Stuck or worn piston rings can be more accurately identified by measuring the compression in the engine cylinders. These readings make it possible to more accurately identify the malfunction and the reasons for its occurrence.

Engine overheating in some cases leads to piston ring damage. If decarbonization did not help, then most likely the rings are either broken or have lost their elasticity as a result of overheating. In this case, only a replacement will help.

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