A question for Dave S.
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Cargo Master
Joined: Mar 2006
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From: Sand GAp, KY
A question for Dave S.
Please bear with me on this one. Is it possible that the head gaskets go bad due to problems with cdr valve? It seems that they go out at the back and that if the cdr is bad and letting it suck the oil in that way it would go to the back to cyclinders. Wouldn't this be like extra fuel in those and make them run hotter than the rest. The reason I am asking is I have been thinking of rerouteing this to a "catch can" for any oil then in to the exhuast near the y-pipe. Would this work? A buddy of mine that was a diesel mechanic in the marines told me that most of the bigger trucks didn't have any cdr type units that they just vented this way but on our light duty trucks people didn't want to smell any oil smoke.
Mountain Pass
Joined: Oct 2004
Posts: 243
Likes: 2
From: Kremlin, Ok
does it not have to have vacuum pulling on the crankcase? I was under the impression it was pretty much like a pcv setup. Where does there air come IN the crankcase at? If you were to run a puke tube instead of the cdr valve, would that not be pouring out oil all the time. I believe the cdr is supposed to be closed at idle. I might be way off on this. I know we have discussed this many times, but I always just see the same old repost about cleaning it. I'd like to hear from someone that has done the puke tube, and how it is working for them. Dave S, you used to have a puke tube on yours, didn't you? why did you go back to a cdr, or did you just do it because you didn't like the fumes, cloud, or what? I'm curious. This is what I'm doing today on my truck. Just went to the Ford parts DC and got some new grommets.
Elder User
Joined: Oct 2006
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Road tubes fell into disfavor more than 40 years ago. They smell bad and make a mess.
I lost a head gasket on my 7.3, and I'm convinced it was from oil getting by the CDR. The mistake I made was not knowing to service the CDR every other oil change combined with overfilling the oil. I'm still using the CDR.
There was a discussion a while back about this. There were a few ideas, including some from Dave S. Seems like no one has had time to experiment yet...
I lost a head gasket on my 7.3, and I'm convinced it was from oil getting by the CDR. The mistake I made was not knowing to service the CDR every other oil change combined with overfilling the oil. I'm still using the CDR.
There was a discussion a while back about this. There were a few ideas, including some from Dave S. Seems like no one has had time to experiment yet...
Post Fiend
Joined: Nov 2003
Posts: 21,285
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From: Nutter Fort, WV
Head gasket failure on the rear cylinders is from the CDR venting oil into the back of the intake throat, which causes most of the vapor to go to the back cylinders.
A properly functioning CDR closes at high vacuum.
This keeps either a clogged air filter or the restriction from the air filter from drawing in to much vapor/oil which the engine uses as fuel.
A clogged air filter could possibly cause a run away engine under the right conditions since enough oil would be just like fuel except no way to regulate it.
As for the CDR, PVC and other such devices, thank the EPA regulations.
Diesels do have a fair amount of blow by, so if it was vented to the air, you will have a cloud and oil will be dropping from the vent tube.
I never ran a road draft tube, during my time around diesels I have seen enough road draft tubes on other motors that I know what it would look like.
And you don't need a vacuum in the crankcase, just a place for the blow by to vent to so there is no pressure buildup, which would blow the seals.
Venting to the intake is the cleanest place for it to go.
A filter/cooler that seperates more of the oil from the crankcase gasses would be a better option.
A properly functioning CDR closes at high vacuum.
This keeps either a clogged air filter or the restriction from the air filter from drawing in to much vapor/oil which the engine uses as fuel.
A clogged air filter could possibly cause a run away engine under the right conditions since enough oil would be just like fuel except no way to regulate it.
As for the CDR, PVC and other such devices, thank the EPA regulations.
Diesels do have a fair amount of blow by, so if it was vented to the air, you will have a cloud and oil will be dropping from the vent tube.
I never ran a road draft tube, during my time around diesels I have seen enough road draft tubes on other motors that I know what it would look like.
And you don't need a vacuum in the crankcase, just a place for the blow by to vent to so there is no pressure buildup, which would blow the seals.
Venting to the intake is the cleanest place for it to go.
A filter/cooler that seperates more of the oil from the crankcase gasses would be a better option.
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Cargo Master
Joined: Mar 2006
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From: Sand GAp, KY
The road tube is what I was refering to on the big trucks. Sorry bout that. I remember the puke tubes. My old 66 Comet had one. I did have my 302 that was in my Bronco vented down under the body with a soup can over it to catch any oil and condensation so it wasn't allover the ground. never liked the idea of venting back into the carb.
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Elder User
Joined: Oct 2006
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OK, but on smaller passenger vehicles and pickups, they've been mostly gone for a long time. Probably the only engine pollution control measure I personally think is a good thing, except that manufacturers don't usually bother to really get it right.
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Cargo Master
Joined: Nov 2003
Posts: 2,585
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From: Duluth, Mn.
There have been numerous attempts at it, not many successful .
I'll give You a little advice.
Keep the diameter of any part at least 1-1/4" or You'll have problems with pressure building, puking oil past seals.
The CDR does see vacuum to pull the CC gasses. So any new design will need a little vacuum to vent the CC properly.
I've got a Walker Airsep on the shelf waiting to go on this spring, when I change heads.
I'll post up how it performs.
Walker Engineering - How It Works
I'll give You a little advice.
Keep the diameter of any part at least 1-1/4" or You'll have problems with pressure building, puking oil past seals.
The CDR does see vacuum to pull the CC gasses. So any new design will need a little vacuum to vent the CC properly.
I've got a Walker Airsep on the shelf waiting to go on this spring, when I change heads.
I'll post up how it performs.
Walker Engineering - How It Works
Post Fiend
Joined: Jan 2000
Posts: 5,330
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From: Dryden, ON, Canada
My 92 Cummins has a RDT on it, and it has no blowby while my 6.9 made clouds in cold weather. A couple friends of mine have 02 and 03 Cummins trucks, and both of those still have RDT's.
Since I reverted my 6.9 back to NA and a CDR valve, the exhaust has the weird smell I always used to notice on my buddy's 6.9 that I could never figure out, it's the oil/water vapor being burned. If my engine gets turboed again, it is definitley not getting a CDR, but, with the amount of blowby an IDI has, I don't want to run a RDT on it either.
Since I reverted my 6.9 back to NA and a CDR valve, the exhaust has the weird smell I always used to notice on my buddy's 6.9 that I could never figure out, it's the oil/water vapor being burned. If my engine gets turboed again, it is definitley not getting a CDR, but, with the amount of blowby an IDI has, I don't want to run a RDT on it either.
Posting Guru
Joined: Jul 2004
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From: West Valley Utah
I think it was cheaperjeeper that was playing around with some kind of bypass or catch system.
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