lucky said:
Hi all:
I'm considering it and am curious to know what it has done for your engine that simply replacing the cd valve won't do. I've done searches but they seem to end with the installation and not if their problems were solved.
Ken
Well, I can address this, as I have done both(RDT and playing around with CDR).
First I'll point out that the "purpose" of the CDR is to route crankcase vapours(which are combustion gasses getting past the rings/and/or oil vapours) into the intake to be reburned, and to regulate crankcase pressures. Other than the fact that it is a tin can, and a small quantity of oil does condense internally and drip back down into the valley, it actually has no bearing on oil consumption. Internally, there is only a spring, and a rubber diaphram. The spring holds it open, and vapours pass through it, and only in the event that somehow the intake got completely obstructed, the diaphram would allow it to close, and block the intake from sucking up the crankcase oil.
If you just want to redirect the oily blow-by out to the road instead of to the rear 2 cylinders, then go for the RDT. The design of the intake would be better if the blowby was simply directed down into the top of the intake so that it was spread evenly to all the cylinders. One of the things I tried was to fit a small tube to the CDR such that the blowby entered the center of the intake manifold to accomplish this. Seemed to work fine, but I dunno if it made any difference. The blowby going to the rear may not actually be the cause of the failure of the rear 2 cylinders at all, as evidenced by the fact that Ford continued to change the headgaskets at the ends to address the high failure rate in these areas...(who knows)
Oil consumption is the other thing. Many guys are under the impression that the CDR has some major function in controlling oil consumption, or that if it is dirty or somehow not functioning correctly, that oil consumption will be the result. Just not so. As I said, earlier, the thing has no function in any kind of control of oil consumption. Just the fact that a few drops of oil condense inside the thing gets everyone all jazzed up.
Oil consumption and blowby are symptoms of engine problems. Some related, some not. Since the blowby is being sucked into the intake via the CDR, it creates a negative pressure in the crankcase area. If that negative pressure is not there(CDR replaced with a RDT), then the combustion gasses leaking past the rings/valve guides etc, can cause positive pressure in the crankcase which tends to push oil past the seals and other places(valve cover gaskets oilpan, injection pump cover etc) and can cause massive oil leaks, that can be hard to fix. An obstructed CDR will usually make itself fairly quickly evident by sudden onset oil leaks around the engine. You can effectively remove the CDR entirely and you won't notice any difference in how the engine runs. Theory has it that if you somehow had an obstructed intake, though that the engine could somehow suck up it's own lubricating oil, and become runaway till it killed itself?!
One other thing I have tried (and currently am running) is a condenser of sorts in conjunction with the CDR inline. This is to try to preserve the negative pressure in the crank area, and somehow prevent some of the blow-by gasses from going into the intake(condense them out into a separate container). My engine has a
lot of blowby. It also leaks oil. It is not long for this world. Without the condenser, it goes through around 1 quart of oil every 300 miles or so. The intake is a wet oily mess, and I can actually see the temp higher on the pyro when I've got my foot into it, and the smoke is a bluish grey. With the condenser inline, I've cut the oil consumption in half(nasty black sludgy oily crap collected in a jug at the bottom of the condenser)the intake is just dusted with oil, and the engine appears to run cooler, and the smoke is distinctly black.
So, on my engine, since it is worn out and has so much blow-by, the RDT only serves to allow the oil to dump to the ground, and there is a massive cloud of stinky messy oil smoke coming out from under the truck(people run up to tell me the truck's on fire..!!) It is not worth it. OTOH, I know that the amount of oil dumping into the intake can't be a good thing, especially in the last dying days this rig still runs...
So, you have to decide what your reasoning for the CDR or RDT is. If you are trying to prevent your rear 2 cylinders from running hotter than the rest, then maybe it is for you. If you are trying to address oil consumption issues that are actually a symptom of engine condition, then it won't make any difference at all, maybe make your problems worse.
..CDR drawing..
..CDR opened..
Hope that clears up the smoke for you a little...
Zigg
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