Lexus Car ES, IS, LS 1998-06

Crankcase Ventilation System

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NOTE
On 4.7L engines, see POSITIVE CRANKCASE VENTILATION SYSTEM

Description & Operation



The 4.0L 6-cylinder engine is equipped with a Crankcase Ventilation (CCV) system. The system consists of a fixed orifice fitting of a calibrated size. This fitting is pressed into a rubber grommet located on the top/rear of cylinder head (valve) cover, a pair of breather tubes (lines) to connect the system components, the air cleaner housing, and an air inlet fitting.

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Fig.

The CCV system performs the same function as a conventional PCV system, but does not use a vacuum controlled PCV valve. The fixed orifice fitting meters the amount of crankcase vapors drawn out of the engine. When the engine is operating, fresh air enters the engine and mixes with crankcase vapors. Engine vacuum draws the vapor/air mixture through the fixed orifice and into the intake manifold. The vapors are then consumed during engine combustion.

Removal & Installation



  1. Pull fixed orifice fitting from valve cover grommet.
  2.  
  3. Separate fitting from CCV breather tube.
  4.  

To Install:


NOTE
When installing fixed orifice fitting, be sure locations of fixed orifice fitting and air inlet fitting have not been inadvertently exchanged. The fixed orifice fitting is Light Grey in color and is located at rear of valve cover. The air inlet fitting is Black in color and is located at front of valve cover.

  1. Connect fitting to CCV breather tube.
  2.  
  3. Return fixed orifice fitting to valve cover grommet.
  4.  

Testing




NOTE
Before attempting diagnosis, be sure locations of fixed orifice fitting and air inlet fitting have not been inadvertently exchanged. The fixed orifice fitting is Light Grey in color and is located at rear of valve cover. The air inlet fitting is Black in color and is located at of valve cover.

  1. Pull fixed orifice fitting from valve cover and leave tube attached.
  2.  
  3. Start engine and bring to idle speed.
  4.  
  5. If fitting is not plugged, a hissing noise will be heard as air passes through fitting orifice. Also, a strong vacuum should be felt with a finger placed at fitting inlet.
  6.  
  7. If vacuum is not present, remove fitting orifice fitting from tube. Start engine. If vacuum can now be felt, replace fixed orifice fitting. Do not attempt to clean plastic fitting.
  8.  
  9. If vacuum is still not felt at hose, check line/hose for kinks or for obstruction. If necessary, clean out intake manifold fitting at intake manifold. Do this by turning a 1/4-inch drill (by hand) through the fitting to dislodge any solid particles. Blow out the fitting with shop air. If necessary, use a smaller drill to avoid removing any metal from the fitting.
  10.  
  11. Return fixed orifice fitting to valve cover and leave tube attached.
  12.  
  13. Disconnect air inlet fitting and its attached hose at front of valve cover. Start engine and bring to idle speed. Hold a piece of stiff paper (such as a parts tag) loosely over the rubber grommet (opening) of the disconnected air inlet fitting.
  14.  
  15. The paper should be drawn against the rubber grommet with noticeable force. This will be after allowing approximately one minute for crankcase pressure to reduce.
  16.  
  17. If vacuum is not present, check breather hoses/tubes/lines for obstructions or restrictions.
  18.  
  19. After Testing, reconnect all system hoses/tubes/lines.
  20.  

 
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