Catch Can disappointment pics inside

[CountryBoy19]

Adding a 2nd can would be a good test to see what is being missed. I have pulled my hose from my catchcan to the intake and it was dry. That's a good indication that nothing significant is blowing through. My original 5.3 intake literally had pools of oil in it and was completely caked up. I don't care about the vapor being recirculated but I would not want my PVC System vented. You will probably get carbon monoxide build up under the hood and could have deadly consequences.

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Adding a 2nd can is actually a terrible way to see what is getting by the 1st. Most catch cans work by a similar principle, even if the execution is slightly varied. If the process by which the byproducts are removed from the first can doesn't fulfill the job entirely then logic says a 2nd can may catch a marginal amount more, but not a significant amount.

IE, Lets say, for the sake of argument, the first catch-can is only removing the most easily condensed crap, the first 10%. The 2nd catch-can may remove another 6%, letting 84% go on through. The fact that the hose is dry isn't necessarily a good indication that nothing else is getting through. It's just an indication that nothing is condensing on the hose. But we're already removed the easiest stuff, so not much is going to get on the hose anyways...

To know for sure, why hasn't anybody taken samples and actually analyzed them? That's the only way to know for sure.

That being said, in regards to venting, I doubt there is much CO in the crank-case vapors. And the venting, per swathdiver's earlier suggestion, would be just like older vehicles and large truck engines. There is a drop tube extending down below the engine so the vapors are easily vented out under the vehicle. I doubt there would be anything accumulating.

 

[bottomline2000]

Adding a 2nd can is actually a terrible way to see what is getting by the 1st. Most catch cans work by a similar principle, even if the execution is slightly varied. If the process by which the byproducts are removed from the first can doesn't fulfill the job entirely then logic says a 2nd can may catch a marginal amount more, but not a significant amount.

IE, Lets say, for the sake of argument, the first catch-can is only removing the most easily condensed crap, the first 10%. The 2nd catch-can may remove another 6%, letting 84% go on through. The fact that the hose is dry isn't necessarily a good indication that nothing else is getting through. It's just an indication that nothing is condensing on the hose. But we're already removed the easiest stuff, so not much is going to get on the hose anyways...

To know for sure, why hasn't anybody taken samples and actually analyzed them? That's the only way to know for sure.

That being said, in regards to venting, I doubt there is much CO in the crank-case vapors. And the venting, per swathdiver's earlier suggestion, would be just like older vehicles and large truck engines. There is a drop tube extending down below the engine so the vapors are easily vented out under the vehicle. I doubt there would be anything accumulating.

Well the logic would be if any is getting into the 2nd can the first is letting at least some fluid by. Most of us that have them catch a lot of oil so they do work. . Not trying to put a science project together but to say it's a terrible idea would mean adding the 1st is a terrible idea to see it the pcv system is letting oil into the intake. Have u seen the inside of an intake with no catchcan..they are literally coated evertpywhere with oil. The hose to the intske is not exempt. Our trucks don't have a drop tube and I'm not sure how exhaust fumes from the dirty side of the engine would not have any CO in it since it's literally blow by from the actual combustion of fuel. By all means you are welcome to experiment but my better judgement tells me otherwise. .

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[bottomline2000]

Adding a 2nd can is actually a terrible way to see what is getting by the 1st. Most catch cans work by a similar principle, even if the execution is slightly varied. If the process by which the byproducts are removed from the first can doesn't fulfill the job entirely then logic says a 2nd can may catch a marginal amount more, but not a significant amount.

IE, Lets say, for the sake of argument, the first catch-can is only removing the most easily condensed crap, the first 10%. The 2nd catch-can may remove another 6%, letting 84% go on through. The fact that the hose is dry isn't necessarily a good indication that nothing else is getting through. It's just an indication that nothing is condensing on the hose. But we're already removed the easiest stuff, so not much is going to get on the hose anyways...

To know for sure, why hasn't anybody taken samples and actually analyzed them? That's the only way to know for sure.

That being said, in regards to venting, I doubt there is much CO in the crank-case vapors. And the venting, per swathdiver's earlier suggestion, would be just like older vehicles and large truck engines. There is a drop tube extending down below the engine so the vapors are easily vented out under the vehicle. I doubt there would be anything accumulating.

Well the logic would be if any is getting into the 2nd can the first is letting at least some fluid by. Most of us that have them catch a lot of oil so they do work. . Not trying to put a science project together but to say it's a terrible idea would mean adding the 1st is a terrible idea to see it the pcv system is letting oil into the intake. Have u seen the inside of an intake with no catchcan..they are literally coated evertpywhere with oil. The hose to the intske is not exempt. Our trucks don't have a drop tube and I'm not sure how exhaust fumes from the dirty side of the engine would not have any CO in it since it's literally blow by from the actual combustion of fuel. By all means you are welcome to experiment but my better judgement tells me otherwise. .

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[CountryBoy19]

Well the logic would be if any is getting into the 2nd can the first is letting at least some fluid by. Most of us that have them catch a lot of oil so they do work. . Not trying to put a science project together but to say it's a terrible idea would mean adding the 1st is a terrible idea to see it the pcv system is letting oil into the intake. Have u seen the inside of an intake with no catchcan..they are literally coated evertpywhere with oil. The hose to the intske is not exempt. Our trucks don't have a drop tube and I'm not sure how exhaust fumes from the dirty side of the engine would not have any CO in it since it's literally blow by from the actual combustion of fuel. By all means you are welcome to experiment but my better judgement tells me otherwise. .

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Yes, sometimes you can certainly tell that something is getting past the first can, but having a 2nd can doesn't quantify, in any way, how much is getting past the cans. And having none show up in the 2nd can is not definitive proof that nothing is getting past the first. Do you see what I'm saying?

I'm not saying they don't work, I'm just questioning the effectiveness. AFAIK nobody has actually done a reliable test to know that nothing is getting past their catch-can. Venting is the only way to ensure nothing is getting to the intake.

In regards to CO: blow-by at idle and low-load conditions is minimal, and minimal CO is produced. The times when blow-by is at it's peak (heavy load) is also when there is likely to be plenty of air circulation to keep any CO concerns at bay. You're acting like the PCV system is a 3rd exhaust manifold pumping pure exhaust back into the intake. Look at the size of the hose and apply some logic. The actual volume of vapors is minimal.

 

[ivin74]

Unless I'm missing something, the crankcase is not metered by any electronics so open or closed (if isolated from the intake air) is not going to set off any codes.

@swathdiver
I disagree with your statement, I left the catch can drain valve open to test your theory and sure thing the check engine light can on.

 

[iamdub]

@swathdiver
I disagree with your statement, I left the catch can drain valve open to test your theory and sure thing the check engine light can on.

That's because the vacuum from the intake manifold sucks through the catch can. You opening that valve created a vacuum leak. It's not that the air coming out of the crankcase was or wasn't detected (because the crankcase has no sensors), it was the vacuum coming from the manifold had nothing to suck on, and the manifold does have a sensor- the MAP. You could have the PCV vent to a hose pointed at the ground if you wanted to be messy. You'd have to plug the vacuum port on the intake manifold, though.

But, if you did have the PCV simply vent to atmosphere with no vacuum assist to pull the vapors out, they'd build up in the crank case and push oil up past the rings into the combustion chambers. Could possibly blow out seals if you do a lot of high-RPM driving. LS engines move a lot of air through them. They have an air inlet and an air outlet just for the crankcase alone.