Tip & How-To about Mercedes-Benz E-Class

PCV - Positive Crankcase Ventilation valve/pipe

1.8) PCV - Positive Crankcase Ventilation valve

What is it? The PCV valve is a thumb sizedplastic elbow that is designed to relieve the build up of pressure in the crankcase. A pipe connects the PCV to the airducting. The function of the PCV is toreturn exhaust gases (blow-by of the piston rings during ignition) from thecrank case to the air intake.

Where is it located? PCV is found on the crankcasebreather pipe or cam cover

How does it work? Some pressure relief systems have a convoluted set of internalpassageways within the crankcase to allow oil mist to settle out and to allow excess pressure tovent in an unrestricted manner through a pipe directly into the air ducting. On other systems thePCV opens when the vacuum in the inlet manifold is low i.e. when the engine isrunning at speed and when the positive pressure of blow-by gases builds up inthe crank case. The PCV is held closefor the most part by the vacuum of the inlet manifold at idle. Often the PCV is unidirectional, allowing gas/airto flow only from the crankcase to the throttle intake. If the valve becomes clogged and stays closedthis can cause pressure buildup in the crankcase and this in turn causes oil toleak through seals etc. Alternatively ifthe valve stays open the ingress of unmetered air can upset thefuel/mix and cause rough idling.

Symptoms of faulty PCV

  • Erratic idling - If the PCV fails to close when at idle then the extra flow of unmetered air from the crankcase can compromise the ECU's ability to maintain a balanced fuel to air mixture. The symptoms very much mimic a leak in the air ducting.

How to check? Remove the PCV and first give is ashake, if it rattles freely this is a good sign. No rattle could indicate a gummed upvalve. **** and blow though it, one way should be easy the other way difficult. If the type of PCV is governed by a vacuumline then the passage of air through the valve will be restricted until asuitable vacuum is applied to it.

How to fix? It may be possible to repair the PCV by rinsing it out with a little fuel or carburetor choke spray to act as a solvent on the oily gunk that has gummed it up. If the valve is beyond reasonable repair then replace it.

NEXT 1.9) MAP - Manifold Absolute air Pressure sensor

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What is a pcv valve


  • How the PCV system works - Agco Automotive www.agcoauto.com/content/news/p2_articleid/197 What are the Symptoms of a Bad PCV Valve. ... Symptoms of a bad PCV valve. We see varied symptoms from a bad PCV valve, depending on the way it fails.
  • Crankcase ventilation system - Wikipedia, the free ... https://en.wikipedia.org/wiki/PCV_valve The PCV valve is only one part of the PCV system, which is essentially a variable and calibrated air leak, whereby the engine returns its crankcase combustion gases ...
  • How does a positive crankcase ventilation (PCV) system ... auto.howstuffworks.com/positive-crankcase-ventilation-system.htm How does a positive crankcase ventilation (PCV) ... Positive crankcase ventilation involves recycling these ... the PCV valve is designed to close off when this ...
  • What does the PCV valve do? - Autorized.com www.autorized.com/auto-maintenance/what-does-the-pcv-valve-do.shtml What does the PCV valve do? By Jakob Jelling Autorized.com. The PCV valve is a control device which sends partially burned gases that come from the engine's ...
  • Jan 17, 2016 | Cars & Trucks

    1 Answer

    how to replace pcv valve


    1. Pull the PCV valve from its housing and place your thumb over the PCV valve opening. You should feel it click. If the click sounds or feels mushy, replace the valve. The PCV (positive crankcase ventilation)valve is a one-way valve that recycles crankcase gases back into the engine to burn.

    Jul 16, 2014 | 1995 Oldsmobile Cutlass Ciera

    1 Answer

    how do you get the pcv valve out of the valve cover


    Usually you grasp it an pull it out.

    Positive Crankcase Ventilation (PCV) Valve Removal & Installation To Remove:
    PCV Valve location (3.3L & 3.8L engines shown, 2.4L similar) chry-04-33-829.gif

    1. Disconnect the vacuum hose from the positive crankcase ventilation (PVC) valve.
    2. Remove the positive crankcase ventilation valve from the valve cover.
    To Install:
    1. Install the positive crankcase ventilation valve in the valve cover.
    2. Connect the vacuum hose to the positive crankcase ventilation valve.
    prev.gif next.gif

    Jan 16, 2011 | 2006 Dodge Grand Caravan

    1 Answer

    how do you change the pvc valve


    Not sure on your engine so heres both types. :-) Hope it helps. Cobra
    Positive Crankcase Ventilation (PCV) Valve — 3.0L (2V) Removal and Installation
    1. Disconnect the positive crankcase ventilation (PCV) valve tube quick-connect from the PCV valve.
    e8e1fc3.jpg
    CAUTION: A new PCV valve must be installed if removed from the cam cover. Damage will occur to the locking mechanism on the PCV valve.
    Remove the PCV valve.
    • Disconnect the PCV valve electrical connector.
    • Rotate to release and remove the PCV valve.
    cb7856a.jpg


    Positive Crankcase Ventilation (PCV) Valve — 3.0L (4V) Removal and Installation
    1. Disconnect the positive crankcase ventilation (PCV) valve tube from the PCV valve
    0f6f63a.jpg

  • CAUTION: A new PCV valve must be installed if removed from the cam cover. Damage will occur to the locking mechanism on the PCV valve.
    Rotate to release and remove the PCV valve.

  • 26db756.jpg

  • Jun 13, 2010 | 2005 Ford Taurus

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