On Saab 9-5 and 9-3 models years 99-03 Saab is suggesting a PCV(Posite Crankcase Ventilation) upgrade. If you are having troubles with oil leaks and/or oil backing up into your turbo causing smoke to billow out of your exhaust pipe this may be what your Saab needs. Regardless of your year or model if you have an oil leak you should check the function of your PCV system. This can be done by checking that all hoses and passages are clear and that the check valve still works as a one way valve.
The need for a crankcase ventilation system comes in play due to piston blow-by. During each power stroke gases escape past the piston rings and into the crankcase. These gases cause high pressure that can push oil out of seals and gaskets. In the old days engines had what they called a road draft tube to vent excessive crankcase pressure. This was a very simple system just a small tube running from the crankcase and down behind the engine opening under the car to the atmosphere. As air flowed by the tube it created a negative pressure pulling the blow-by out of the engine.
the 60's Smog control came into play and the PCV system was created.
This system draws the crankcase blow-by back into the air intake and re-burns
these gases keeping them from the atmosphere. This system is comprised
of 2 hoses and a check valve. One large hose from the valve cover to the
air cleaner and one small vacuum hose from the valve cover to the intake
with a check valve in-between on Turbo models (non turbo has no check
valve). This is the most basic of systems that you may find on older Saab
models. Today it is basically the same but there is a few more hoses and
a oil separator box connecting to the turbo.
Saab has determined that the oil separator box on 9-3 and 9-5's PCV system has inadequate flow. This is responsible for oil leaks at the timing cover area and smoke from the tail pipe during start up. It is also recommended to change the hoses and check valve at the same time to be sure all is in proper shape.
(This article is meant to educate a consumer,or as a guideline for professionals. You can cause serious damage to your vehicle and/or cause yourself injury. Only those qualified should attempt repairs. I do my best to assure that the above info is correct but take no responsibility for any damages incurred.)
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