If you’ve ever opened your car’s oil cap and noticed smoke or air coming out, your engine may have a serious problem. In this video, I’ll explain the reasons why this happens, what damage it can cause, and how to fix it before it becomes a major failure.
Causes
- Piston Ring Wear: Piston rings seal the combustion chamber to prevent gases from leaking into the crankcase. When they are worn, these gases pass to the lower part of the engine and generate pressure, causing air to escape through the oil cap.
- Clogged or Faulty PCV Valve: The PCV valve is responsible for recirculating combustion gases back to the intake. If it is clogged or damaged, pressure builds up inside the engine and gases seek an exit through the oil cap.
- Cylinder Wear: Over time, cylinders can lose their sealing ability due to wear. This allows combustion gases to leak into the crankcase, increasing internal pressure and causing air to leak through the oil cap.
- Engine Debris Buildup: Poor maintenance and the use of low-quality oil can cause sludge to build up inside the engine, clogging the ventilation passages and increasing pressure in the crankcase.
Diagnosis
- PCV Valve Check: Remove the PCV valve and check for clogging or wear. If you don’t hear the characteristic sound of the internal valve moving when you shake it, it probably needs to be replaced.
- Engine Compression Test: Use a pressure gauge to measure the compression in each cylinder. If one or more cylinders show lower than normal values, the piston rings or cylinders may be worn.
- Cylinder Leak Test: Compressed air is injected into the combustion chamber with the piston at its top dead center. If air escapes into the crankcase, it means that the piston rings are allowing combustion gases to pass through.
Solutions
- PCV Valve Replacement: If the valve is clogged or faulty, it is important to replace it to restore proper crankcase ventilation.
- Oil Change and Internal Engine Cleaning: If there is sludge build-up, it is recommended to perform internal cleaning with specialized products and use good quality oil to prevent the formation of new residue.
- Engine Repair: In cases of wear on the piston rings or cylinders, it will be necessary to disassemble the engine to perform a rectification or replacement of components. This is a major repair and should be carried out by a specialist.
Additional Tips
- Perform Regular Oil and Filter Changes: Use quality products to ensure engine longevity.
- Periodically Check the PCV Valve: Replace it if necessary to prevent pressure buildup.
- Avoid Forcing the Engine: Allow it to reach its working temperature before overstressing it.
- Seek Professional Inspection: If you notice smoke or air coming out of the oil cap, have the problem checked as soon as possible to avoid further damage.
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