Que es la válvula PCV - Funcionamiento - Diagnóstico

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En este artículo chica mecánica explica que es la válvula PCV, su funcionamiento, como realizar pruebas y cuales son las fallas para corrregirlas.

The PCV valve


When an engine is running, the exhaust gases blow through the piston rings to the crankcase, this process also occurs to a lesser extent during compression. In earlier times, these hydrocarbon-laden gases carrying oil droplets from the crankcase could escape into the atmosphere and, as a result, these engines were always leaking oil. It was very normal at that time, even the estoperas and together were made to contain large boats, not much effort was made to make hermetic fair, far from it.

This process took the form of a problem from the 1950s, when it was found that these gases caused pollution and increased smoke in the cities. In this way, and, motivated to an invention of the GM to ventilate the tanks of war, where the exhaust gases were recirculated to the intake manifold that casually reduced the emissions of these machines, already for the decade of the 1960s it was implemented compulsory in automobiles and in this way harmful hydrocarbons do not escape into the atmosphere.

Then the PCV valve (PCV: Positive Crankcase Ventilation Valve) allows the passage of oil and hydrocarbon vapors generated in the crankcase to the intake manifold and then to the combustion chambers where they are burned, thus eliminating the high pressure generated in the crankcase. In turn, this valve must close at the time of a deceleration of the engine, since the overpressure produced in the intake manifold would go to the crankcase generating the same problems.

animación funcionamiento gases motor

Functioning:

In general, the PCV is closed by the spring when the engine is off or if an intake deflagration occurs. It closes for in a first case to avoid the entry of atmospheric air to the crankcase rich in steam water that, if it liquefies inside the engine, produces mud and other undesirable things, and for the second case avoid the entrance of overpressure or even flame the oil ... with the dangers that this implies.

When the machine is turned on at idle speed or minimum RPM, the PCV is semi-open due to the high vacuum that occurs at the engine intake. This is done because the mixtures usually do not contain a lot of air and it would not be a good idea to try adding oil, gasoline and little air to ignite it. It would not burn out completely.

When we accelerate the engine, the vacuum of the intake manifold decreases due to the entry of more air. This makes our PCV in working position and in this way as more air is entering the intake, we can put more oil, which we can burn without problems in combustion.

Funcionamiento del válvula PCV

In the previous image you can see the animation of how this process is.

As you can see, the valve only lets flow in one direction (out of the crankcase). That is why they usually bring a little arrow, which indicates the direction of the flow so that it is installed correctly

Where are they?

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It is usually connected to the intake air inlet by a hose about 2 centimeters in diameter. Not necessarily the side of the intake manifold is by hose. Below I show you an image of what a PCV valve looks like and its mounting types.

Tipos de válvulas PCV y su montaje real

Problems

If the PCV valve becomes clogged or very clogged, A LOT OF PRESSURE is generated IN THE CRANKCASE that bursts the crankcase seals, the cylinder head cover, causing oil leakage, even loss of engine performance.

When it is open, the faults are accumulation of oil in the intake hoses, spark plugs dirty by traces of oil and in some cases very severe (when the engine passes oil) can dirty the air filter of the engine with traces of oil.

Diagnosis

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If oil leakage problems are noticed by seals and engine seals

Or if when removing the oil dipstick, too much vapor is visible.

Or if we have spark plugs that after a few days of having cleaned them, they get dirty and there are no symptoms of compression loss (the engine is running oil).

The most likely thing is that our PCV needs maintenance.

Test the PCV valve

Checking it is pretty simple.

- Remove the valve.

- Blow against the direction of the arrow. There should be no flow.

- Blow in the direction of the arrow. There should be flow.

If it is very dirty, it is advisable to clean it with some solvent that does not damage the internal gums.

And well, that's all for the moment.

I hope you like it,

Questions or doubts?

Use the form below to make them, we will gladly respond.

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Escrito por

Dennis García

Chica Mecánica

24/08/2018

Grade 
08/25/2018

Mejor explicado que muchos

Caramba, colocaste hasta algo de historia en el articulo. Genail 5 estrellas para ti.

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    Que es la válvula PCV - Funcionamiento - Diagnóstico

    Que es la válvula PCV - Funcionamiento - Diagnóstico

    En este artículo chica mecánica explica que es la válvula PCV, su funcionamiento, como realizar pruebas y cuales son las fallas para corrregirlas.

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    • Asked by Juan Requena
      on 08/25/2018
      ¡Excelente para hacer diagnosticos! Pero una pregunta. ¿Es posible recuperar esta válvula? Answer:
      Claro Juan, es posible recuperarla si no está dañado el resorte. Solo con limpiarla estará como nueva. : )
    • Asked by Edwin
      on 09/26/2018
      Hola Yo cambie la válvula pcv de mi carro y noto que se agita todo el rato, suena como si se la estuviera sacudiendo constantemente y la usada que saque, deja pasar el aire en ambos sentidos. Es Normal?Tambien esta botando aceite por la tapa del aceite y la tapa de válvulas (ojala ya no bote después del cambio de la valvula pcv) Mi vehiculo es Dodge grand caravan 1994 La válvula que instale no lleva resorte alguno!! Answer:
      No es normal que la PCV condusca en ambos sentidos. Si es asi, esta dañada. Y es raro que no posea un resorte. Por lo general traen uno a menos que sea una check normal. En cuanto a la falla que comentas, ¿instalaron en el sentido correcto la PCV?
    • Asked by a guest
      on 10/08/2018
      Como incorporar una válvula PCV común a mi pickup Chevrolet 1966 con decantador de aceite y mangueras. Gracias. Answer:
      Caramba....con mangueras es algo complejo, tendrias que hacer muchas curvas y tendrían que tener desnivel que vacie el aceite condensado nuevamente al motor. Deberias es de hacer un trabajo con la tapa valvulas, crear un sistema de laberinto para que condense lo más posible y le colocas mallas metalicas de esas para mosquitos para ayudar a que el aceite evaporado se pegue alli.
    • Asked by a guest
      on 11/03/2018
      Excelente artículo, entonces en mi caso hay aceite en las mangueras y múltiple de admisión por la PCV abierta. Mi pregunta esta condición puede causar perdida considerable de rendimiento del motor? Y otra: esto puede generar una falla del sensor de O2? Answer:
      Que tal, Claro, si queda cerrada el motor se asfixia, si queda abierta produce carbón excesivo de aceite en bujias, sensores de oxigeno y convertidor catalitico que van restando rendimiento paulatinamente hasta que empiezan las fallas.
    • Asked by francisco padron
      on 11/18/2018
      buenas noches mi carro no enchumba bujia pero pasa aceite para el escape y vota humo azul no pierde compresion ni fuerza lo e anillado dos veces y sigue el mismo problema ..... ayudenme 04144345128 Answer:
      Que tal Francisco, tienes los gorros de valvulas desgastados.
    • Asked by Luis
      on 11/24/2018
      Hola Dennys. Saludos. Cual de las tres imagenes a las que haces referencia es la valvula pcv del chery orinoco 2016. No la encuentro por ningun lado. He buscado y nada Answer:
      Ninguna Luis. la PCV del orinoco se encuentra en la manguera que va hacia el cuerpo de aceleración, que conecta con la manguera luego del MAF. Es una PCV de línea.
    • Asked by GAILER PALENCIA
      on 01/10/2019
      Hola muy profesional su explicación preguntas quisiera saber mi motor es un dodge 318 8v. tiene la pcv en el tapa valvula con una manguera conectada al carburador esta hace una especie de succión esta bien conectada 2 cuando enciendo el carro me hace una vibración que se sacude de lado a lado e sacado la pcv y la tapo con el dedo y se mormaliza e notado que la manquera que va al carburador estaba floja succionando aire cual puede ser la falla y 3 las bujias tengo que limpiarlas cada tres o cuatro dias sucias de carbon Answer:
      GAILER, si el motor no está pasando aceite es posible que la PCV este dando problemas o esté conectada alreves. Pruebala a ver si tiene estaqueidad y que no este demasiado sucia con aceite que la obligue a estar abierta, que es lo más seguro por el problema de las bujias que tienes.

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