Toyota Celica 1986-1993 Repair Guide

Crankcase Ventilation System

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OPERATION





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Fig. Fig. 1 PCV system operation2S-E engine shown



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Fig. Fig. 2 PCV valve operationCelica



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Fig. Fig. 3 PCV valve location5S-FE engine shown

A positive crankcase ventilation (PCV) system is used on all Toyota gasoline engines vehicles sold in the United States. Exhaust blow-by gases are routed from the crankcase to the intake manifold, where they are combined with the fuel/air mixture and burned during combustion. This reduces the amount of hydrocarbons emitted by the exhaust.

A valve (PCV) is used in the line to prevent the gases in the crankcase from being ignited in case of a backfire. The amount of blow-by gases entering the mixture is also regulated by the PCV valve, which is spring loaded and has a variable orifice.

The important components of the PCV system are:



PCV valve
 
Valve cover
 
Air intake chamber
 
Ventilation case
 
Hoses, connections and gaskets
 

SERVICING



PCV system service is relative easy, as it consists of making sure that the PCV valve is working and that all the hoses and connection are tight and in good shape. A clogged PCV valve and/or restricted hoses can cause the engine to run poorly.

Check the attaching hoses for cracks or clogs by visually and physically inspecting them. Check the PCV system hoses and connections to ensure that there are no leaks, then replace or tighten, as necessary.

To check the valve, remove it and blow through both of its ends. When blowing from the side which goes toward the intake manifold, very little air should pass through. When blowing from the crankcase (valve cover) side, air should pass through freely.

Replace the valve with a new one, if the valve fails to function as outlined.


WARNING
Do NOT attempt to clean or adjust the valve. Replace it with a new one.

REMOVAL & INSTALLATION



Remove the PCV valve from the cylinder head cover or from the manifold-to-crankcase hose by unthreading or pulling out. Install by rev