Volvo AWD 850 Forum

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1995 850 turbo pcv valve? 850

The Haynes seems to indicate where the pcv valve is for a non-turbo, then does not discuss location or if there is one for the turbo model. If there is not one, how does moisture in the crankcase during winter escape?








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    1995 850 turbo pcv valve? 850

    The turbo has a crankcase ventilation 'system'. What it does not have
    is the flame trap. Sometimes the two are used when the other is meant.

    www.alldatadiy.com has the technical description and diagrams that
    describe the system in detail (costs $25/yr):

    CRANKCASE VENTILATION

    Crankcase gases are removed from the cylinder block (and cylinder head to an extent) to an oil trap (1) where oil is separated from the crankcase gases and returned to the oil sump. The hose to the cylinder head equalizes differences in pressure between the upper and lower parts of the engine.

    When the Turbocharger cuts in, crankcase gases flow through the crankcase hose (5) through heating nipple (6) to the fresh air intake.

    When there is little load on the engine or when it is idling there is no under-pressure in the fresh air hose upstream of the Turbocharger and only a small quantity of crankcase gases are formed. Because of this a vacuum hose (7), to lead crankcase gases directly to the intake manifold at low loads, goes from the heating nipple to a calibrated intake downstream of the throttle.

    The heating nipple is calibrated to provide a controlled flow of crankcase gases. Power to the PTC type nipple is supplied by the engine management system main relay and prevents water vapor in the crankcase gases from freezing in the fresh air intake hose at low temperatures.

    The PTC nipple temperature stabilizes at approximately 80°C (176°F) as soon as the engine is started.
    .
    .
    .

    Remember the good old days when it was just a hose to the block
    and a valve stuck into the cylinder head cover :)









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    1995 850 turbo pcv valve? 850

    PCV is a positive crankcase ventilation valve...last time i checked,it recirculates the blowby gases in the crankcase back into the engine for reburning rather than dumping them out into the atmosphere.

    back in the old days,there was a tube that like a short exhaust pipe that took these gases and just dumped them under the car and into the atmosphere.

    now with EPA calling the shots,this is a no-no.







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