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This is the second thread I am making for my truck and I would like to make a follow up thread later about doing the water pump. Thanks to oldrebuiltdodge and LMJD for your pointers, anyway I took off the (CDR Valve) crankcase ventilation assembly today and cleaned the crankshaft intake and bought a nice rubber plug from the hardware store and now I'm using the old intake fitting and JV welded a copper 90 thats about 3/4 in. Anyway I bought heater hose from pep boys rubber wound with fabric says high temp but the diameter inside is 5/8 of an inch. Seems like it would be enough for an road draft tube right? Please let me know if I should go a different route with the size and material. Thanks in advance.
It's a 1988 f350 xlt 7.3 non turbo idi . 217 thousand miles and bought for 4 grand from a guy that was okay to it as far as I know, but told me to check the oil regularly, real emphatic on that. When I did the oil change once the truck changed hands, it dropped about a gallon of black oil which was upsetting. I did the 3 gallons of Del 400 and used a matching wix filter from NAPA and drove around to a neighboring town, when I checked the oil at idle, oil vapors were coming out pretty good from the dipstick hole. I figured the smart thing to do is minimize heat in the back cylinders would be to do this whole operation. Using wix air filter, bolt was very oily which someone said you may want to do the RDT
 

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Please let me know if I should go a different route with the size and material. Thanks in advance.
The best route you could go would be to leave the original CDR system alone. Every "keyboard mechanic" that gets on a IDI site blames the CDR for everything but tire wear, plus most don't even know how the CDR works. If you're referring to the air cleaner holddown bolt, the bolt plus the whole inner intake will be oily and black on ANY diesel since diesels don't have throttle plates like a gas engine. There's been a few guys who had to install an RDT and it was restrictive so that the crankase pressure was enough that they forced oil past the rear main seal and front crankshaft seal.
And there's no way a CDR can cause excess oil consumption. In fact in the excess oil consumption diagnosis sections of both the Ford and Navistar shop manuals the CDR is never mentioned.
 

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The best route you could go would be to leave the original CDR system alone. Every "keyboard mechanic" that gets on a IDI site blames the CDR for everything but tire wear, plus most don't even know how the CDR works. If you're referring to the air cleaner holddown bolt, the bolt plus the whole inner intake will be oily and black on ANY diesel since diesels don't have throttle plates like a gas engine.
So you don't recommend me doing the rdt? I have a new cdr already being ordered through ebay but the more I read the more I thought it was more of an epa standard to have. Anyway, if that's the case I'll just install a new cdr when it arrives to be safe. Thanks
 

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No matter how you do it, the crankcase must be properly ventilated, or you will blow out every seal and gasket on that engine. The way the factory did it is most likely the most efficient way to do that. Which is essentially agreeing with LMJD. I would strongly advise you to check the oil level with the engine off, not running, because you get a better measurement of where the level actually is, and you won't tend to overfill it. As far as the vapor coming from the dip stick tube, some of that is normal, but a lot under pressure might be caused by blow-by, which indicates worn rings. The test for that measures the pressure built up with everything plugged, I don't recall what the max. pressure is though. Maybe someone here knows that.
 

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You're welcome. And as Oldrebuiltdodge posted, excessive blow-by (worn rings, scored cylinder walls, etc.) can only be confirmed by temporarily blocking off the CDR so all blow-by is trapped in the crankase, then a manometer is connected to the oil fill spout and if its reading is over 6" at max engine no load RPM, blow-by is excessive. And as far as an oil change, if I remember right, with a filter change these engines only hold 10 quarts. One or two more if you use the bigger PS filter.
 
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