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My CDR experiment

ak diesel driver

ak diesel driver

6.5 driver
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So I decided to experiment with my CDR. I first tried using a standard vac/pressure guage but it wasn't sensitive enough, so I bought a digital manometer off ebay. My initial results are kind of interesting. My high mileage 238k motor has lots of blowby and I'm sucking about 1 gallon of oil thru my CDR between oil changes. With the manometer hooked up and the engine up to temp I'm running somewhere between +.4"-+.7" at idle. With just about any change in engine rpm it goes negative pretty fast. At 45mph and about 3lbs boost it's showing -3.0". At 55mph and about 4.5lbs boost it's showing -4.0". At 65 mph I'm running about 6lbs boost and showing about -4.5"--5.0". At WOT and about 10lbs boost I'm showing about -5." thru-6.5". The most I ever peaked at was -7ish. I didn't write any of this down so I might update these #s later. I'm going to run it this way for awhile and try to establish some sorta baseline.
Then I'm going to swap in my modified CDR with it's ability to adjust and see what if anything works better. I've heard the CDRs are supposed to shut at high boost but as far as I can tell mine never has, and no it's not the original.
 

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Here's some pics of the inside of a CDR. Not much too them diaphram and a spring. I also tried gas,solvent,ether,etc and never found anything that would harm the diaphram so I wouldn't worry to much about trying to clean one as long as you don't get anything on the backside of the diaphram thru the vent hole you should be fine.
 

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Here's my completed modified CDR. Pretty simple a spring that pushes against the diaphram with the ability to change the tension on it.
 

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A little update. 10* this morning and when I started it the pressure spiked tp +2.85. It stayed higher and gradually lowered down as the engine warmed up. I would assume this is from the contraction of cold parts allowing more clearance and thus more blowby.
 
Why wouldn't one plumb the crankcase to open air, or pre-turbo or some other source of vacuum to keep the crankase at zero or negative atmosphere at ALL TIMES?
 
3500GMC said:
Why wouldn't one plumb the crankcase to open air, or pre-turbo or some other source of vacuum to keep the crankase at zero or negative atmosphere at ALL TIMES?
Click to expand...

Ummm, it is already :) What do you mean? The problem with having it connected to the intake is high oil consumption because it can suck the oil into the turbo. The CDR's job is to limit the amount of vacuum in the crankcase, but its not always effective and you get a lot of oil consumption.
 
buddy said:
Ummm, it is already :) What do you mean? The problem with having it connected to the intake is high oil consumption because it can suck the oil into the turbo. The CDR's job is to limit the amount of vacuum in the crankcase, but its not always effective and you get a lot of oil consumption.
Click to expand...

If you were to have a more effective vent (so as to not draw oil) you wouldn't have oil consumption problems... Maybe. The CDR is just a valve in effect, not a filter or isolator for/from oil emulsified air. The right side valve cover has some sort of medium that kinda works. Wonder if one couldn't expand upon that?

I like the idea of the tweekable CDR though...
 
the cdr is supposed to close in high vacuum situations, I've heard 5-6". My tests so far indicate that's not happening. I would think ideally it should be designed so it maintains a very slight vacuum but it appears to pretty much stay open. Maybe with a low blowby engine it would make enough vacuum to close it but I doubt it. My thought was to see if I could adjust it to greatly reduce the oil consumption while still maintaining some vacuum. Obviously at low engine speeds and lots of blowby that won't happen.
 
ak diesel driver said:
the cdr is supposed to close in high vacuum situations, I've heard 5-6". My tests so far indicate that's not happening. I would think ideally it should be designed so it maintains a very slight vacuum but it appears to pretty much stay open. Maybe with a low blowby engine it would make enough vacuum to close it but I doubt it. My thought was to see if I could adjust it to greatly reduce the oil consumption while still maintaining some vacuum. Obviously at low engine speeds and lots of blowby that won't happen.
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I'm glad i ain't the only one that found that out.:thumbsup:

Exactly the reason i vented to the world,either that or an oil seperator is the only way to keep most of the oil where it belongs.
Oil pull over is not a problem in healthy engines with low blowby.
With high blowby you will loose some oil to the to the world vent as well but far less as compared with the stock the CDR/intake set up.

CDR is ....emision control..emision control..emision control,,,and....emision control only;)
 
bison said:
[/B] I'm glad i ain't the only one that found that out.:thumbsup:

Exactly the reason i vented to the world,either that or an oil seperator is the only way to keep most of the oil where it belongs.
Oil pull over is not a problem in healthy engines with low blowby.
With high blowby you will loose some oil to the to the world vent as well but far less as compared with the stock the CDR/intake set up.

CDR is ....emision control..emision control..emision control,,,and....emision control only;)
Click to expand...

i am kind of curious to see some pics of your provent unit.... i have built a catch can on all of our trucks, and a drain cock on the bottom to drain out crap.... sure seems to reduce oil consumption and keeps the oil in the motor cleaner, longer..... also that adjustable cdr is some neat stuff, must be due to the long winters up north...LOL
 
turbonator said:
i am kind of curious to see some pics of your provent unit.... i have built a catch can on all of our trucks, and a drain cock on the bottom to drain out crap.... sure seems to reduce oil consumption and keeps the oil in the motor cleaner, longer..... also that adjustable cdr is some neat stuff, must be due to the long winters up north...LOL
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yeah we did our own searchin...... heres a linky,linky.....http://www.thetruckstop.us/forum/showthread.php?4489-Alternative-for-pesky-CDR-pic&highlight=provent

be cool to do this same test with the provent system as well....
 
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