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Catch can anybody running one on the new HD

2020_3500HD

By 2020_3500HD
in 6.6L Gas V8 (L8T)

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Jettech1
Jettech1

I only have one, never heard of 2 being needed for any engine.  I always use JL catch cans.  They run about 150 on Amazon and are super easy to install.

Jettech1
Jettech1

Perhaps, he's right.  But the bypass gasses are intermingled in any engine.  They aren't totally separate in any case.

Pryme
Pryme

Yeah that’s true most exhaust has a drone somewhere. 

Posted Images

djxn40 Enthusiast

djxn40

Posted
Posted
25 minutes ago, mrjulian416 said:

That's a ton... oil/water or mostly oil, mostly water?

Its oil. Super thin oil but oil nonetheless.  That's pretty on par with my 5.3. So to me GM's oil separator didn't change anything. Makes me glad I installed one now though. 

6.6HD Enthusiast

6.6HD

Posted
Posted
On 1/11/2021 at 3:44 PM, djxn40 said:

Is this the pcv line? I believe it to be. But its totally different than the 5.3 I traded in. I pulled this line out and there is oil in it. I've installed the catch can I'm just trying to confirm this is the right line.. any help is appreciated. 

20210111_154922.jpg

Where does the outflow connect?  To the top of the throttle body or bottom?

skorpyd Enthusiast

skorpyd

Posted
Posted

I've had at least 20 different GM trucks in my lifetime and never had a catch can.  Obviously I'm not a mechanic, but am curious about the purpose and if I should put one on my 2020 3500 that's about to turn over 50,000.

D A Enthusiast

D A

Posted
Posted
1 hour ago, skorpyd said:

I've had at least 20 different GM trucks in my lifetime and never had a catch can.  Obviously I'm not a mechanic, but am curious about the purpose and if I should put one on my 2020 3500 that's about to turn over 50,000.

I’m guessing if you’ve had at least 20 different GM trucks, I’m thinking they didn’t have a tremendous amount of miles on them? Perhaps the catch can is more important if one plans to keep their truck a long time and put a lot of miles on them? I sure wish I knew more about this as the folks that have them have shown they work. But the video posted about the 6.6 show the valve covers would prevent an issue. 

djxn40 Enthusiast

djxn40

Posted
Posted
On 1/20/2021 at 10:31 AM, 6.6HD said:

Where does the outflow connect?  To the top of the throttle body or bottom?

In and out refer to the catch can. So from the in on the picture to the in on the catch can. The other end of the pcv line is where you run the out from the can.

20210124_083858.jpg

skorpyd Enthusiast

skorpyd

Posted
Posted (edited)
On 1/23/2021 at 7:08 PM, D A said:

I’m guessing if you’ve had at least 20 different GM trucks, I’m thinking they didn’t have a tremendous amount of miles on them? Perhaps the catch can is more important if one plans to keep their truck a long time and put a lot of miles on them? I sure wish I knew more about this as the folks that have them have shown they work. But the video posted about the 6.6 show the valve covers would prevent an issue. 

I've had mostly used trucks along the way.  My first new was an 89, on which I put over 350k on and never had anything go wrong with the motor. many others in excess of 100k and a couple in excess of 200k

 

Upon some research it seems  a catch can is used mainly with direct injected engines.    

 

So a new question would be, with 50,000 miles on the truck already should I do something to  to the intake system before adding a catch can system?

Edited by skorpyd
Another JR Senior Enthusiast

Another JR

Posted
Posted (edited)
7 hours ago, skorpyd said:

I've had mostly used trucks along the way.  My first new was an 89, on which I put over 350k on and never had anything go wrong with the motor. many others in excess of 100k and a couple in excess of 200k

 

Upon some research it seems  a catch can is used mainly with direct injected engines.    

 

So a new question would be, with 50,000 miles on the truck already should I do something to  to the intake system before adding a catch can system?

You could examine the inside of the intake system downstream of the PCV line and look for evidence of significant oil contamination.  If there is none after 50,000 miles, you don't need a catch can.  The intake manifold is the coolest part of the intake system that is downstream of the PCV line.  If you are not getting oil droplets or oil vapor condensation there, then the PCV system is working as designed and the fuel and oil vapor entering the intake via the PCV line is being burned.  Everything downstream of the intake manifold is warmer than the intake manifold and would not create condensation if you aren't seeing condensation in the intake manifold.  Catch cans themselves act as condensers in addition to having some effectiveness as oil droplet separators, depending on their design.  If you are getting actual oil droplets coming through the PCV line then a catch can can reduce the passing of those droplets into the intake.  If you are not getting droplets in the PCV line and not getting condensation on the intake manifold walls without a catch can, then a catch can if it collects anything is acting as a condenser for vapor that would have been burned.  Nothing wrong with that, but in such a case the catch can is not necessary to reduce intake system deposits.  The fact that an installed catch can collects liquid is not itself proof that a catch can is actually needed. 

Edited by Another JR
djxn40 Enthusiast

djxn40

Posted
Posted
9 hours ago, Another JR said:

You could examine the inside of the intake system downstream of the PCV line and look for evidence of significant oil contamination.  If there is none after 50,000 miles, you don't need a catch can.  The intake manifold is the coolest part of the intake system that is downstream of the PCV line.  If you are not getting oil droplets or oil vapor condensation there, then the PCV system is working as designed and the fuel and oil vapor entering the intake via the PCV line is being burned.  Everything downstream of the intake manifold is warmer than the intake manifold and would not create condensation if you aren't seeing condensation in the intake manifold.  Catch cans themselves act as condensers in addition to having some effectiveness as oil droplet separators, depending on their design.  If you are getting actual oil droplets coming through the PCV line then a catch can can reduce the passing of those droplets into the intake.  If you are not getting droplets in the PCV line and not getting condensation on the intake manifold walls without a catch can, then a catch can if it collects anything is acting as a condenser for vapor that would have been burned.  Nothing wrong with that, but in such a case the catch can is not necessary to reduce intake system deposits.  The fact that an installed catch can collects liquid is not itself proof that a catch can is actually needed. 

I don't necessarily disagree.  However with the amount you catch in the can. I feel more comfortable using a can. I'm not saying it won't burn it without a can but no doubt its a lot getting past the pcv line. With a can being so inexpensive. To me its definitely worth it. And one things for certain... it won't hurt to run a can

Another JR Senior Enthusiast

Another JR

Posted
Posted

I agree there isn’t any down side to a properly designed and maintained catch can.  Nothing wrong with being conservative. 

D A Enthusiast

D A

Posted
Posted

I’m not against a catch can but would be concerned over a denial of warranty with the addition of a catch can. I lack the financial resources to take GM to court. Not sure if Magnuson Moss would work or not. It seems from spending way too much time reading about this subject that timely oil changes and using the correct oil goes a long way to help. 

L8T Enthusiast

L8T

Posted
Posted
On 1/12/2021 at 1:16 PM, djxn40 said:

This is after 300 miles or so of highway driving. So imagine pulling

Screenshot_20210112-142656_Gallery.jpg

Wow! That’s more than I thought there would be. 
So is there one of those on each calve cover?
Also where did you get the catch can? 
And what size of hose does it need?

Thanks in advance. 

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