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All 6.9L and 7.3L diesel engines are equipped with a CDR (Crankcase Depression Regulator) valve. Even the new 7.3L Power Stroke is also equipped with the same valve. The CDR valve is one of the leading causes of head gasket failure in these engines. The CDR valve is responsible for controlling the pressure/vacuum in the engine crankcase, and seperating the oil mist from the air and returning the oil to the crankcase. The CDR valve should be serviced every second oil change or when signs listed below are seen.
When the CDR valve is not properly serviced, engine oil enters the air intake and is drawn into the engine. The diesel engine will burn this oil as fuel, however, it is heavier and thicker than diesel fuel and, having greater BTU output, causes excessive heat in the cylinder. Due to the intake manifold design, most of the oil will migrate to #7 and #8 cylinders; the last two cylinders in the rear by the firewall. The increased temperature here will cause the cylinder head to lift off the gasket and allow water or oil to leak out the back of the cylinder head where it meets the block.
To check your CDR valve, remove the air cleaner hold down bolt and inspect it. If the bolt is covered with engine oil mist, it's time to service your CDR valve! Ford calls this item a "Adapter assembly for Crankcase Ventilation" Part number E3TZ-6A665-A or IH part #1805319C1
To service the CDR wash with a solvent, allow to dry, do not use compressed air to dry. There is a small hole in the CDR back cover, ensure it is clean and open. If black chunks of rubber are visible in the intake, on the screen then the rubber membrane has disintegrated, replace the CDR.
I did not touch mine for 13 years, and when removed and cut apart it was as good as new.........
thats ok.that's the nature of the beast.she's bound to eventually coat the intake with a light film down the intake because of the mist.that doesn't indicate cdr failure.you could clean the intake all up and replace the cdr.iv no doubt that over a month or two she'd look just the same again.it goes down there to be re-burnt this is why the idi uses about a quart of oil every 3k miles or so.just do as described by PLC and wash it out first.if you see no sign of black chunks when rinsing,then she's still good.
i'll probably have to clean out my intercooler now every couple years too.
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