Catch Can / LS6 Valley Cover Working in Unison?

[Steve Cole]

So, I want to run both a oil catch can and the LS6 valley cover together on my 2005 5.3 truck engine. The idea being the catch can will snag any oil blow-by that the valley cover doesn't. I know opinions vary wildly if you need one, the other, or both but that isn't the topic here. I am just looking for the facts of how it should all be connected. For those who are in the know, please tell me if this is THE CORRECT WAY to plumb this. BTW.. This catch can does not have a breather or vent on it, it is a closed loop system. Thanks in advance!

[dayj1]

Originally Posted by Steve Cole

So, I want to run both a oil catch can and the LS6 valley cover together on my 2005 5.3 truck engine. The idea being the catch can will snag any oil blow-by that the valley cover doesn't. I know opinions vary wildly if you need one, the other, or both but that isn't the topic here. I am just looking for the facts of how it should all be connected. For those who are in the know, please tell me if this is THE CORRECT WAY to plumb this. BTW.. This catch can does not have a breather or vent on it, it is a closed loop system. Thanks in advance!

I assume that you decided on the ls6 valley cover because it does a better job of not allowing oil to pass through (compared the the orifice in the passenger side valve cover). If so, I don't really follow why you'd still pull from the passenger valve cover. I'd think you'd want to just cap the valve cover and pull only from the valley cover. Otherwise your diagram makes sense to me.

[Steve Cole]

That was my thought as well. I pulled that diagram from the LS1tech website. There were multiple diagrams with all kinds of configurations but they all pretty much had the passenger side valve cover providing "clean air" . I was doing a "sanity check" by asking this question. I didn't understand this logic so I posted here hoping someone could enlighten me.
Thanks for your reply.

[Steve Cole]

Originally (from GM) the passenger side valve cover plumbed to the back of the throttle body, like in the diagram. Hopefully someone with some knowledge in this area will chime in. Thanks.

[sprint_9]

From what I have gathered by reading and research is that a stock setup always pulls across the engine when venting. So for example, stock trucks pulled from an inlet on the passenger side valve cover across the engine to an outlet on the drivers side. Some of the cars pull from both valve covers and then out the valley. What needs to be accomplished is even ventilation of the engine, or as close as can be achieved.

I think this would be the best way to do it, and is similar to what Im planning on doing with mine. I would maybe consider enlarging the fixed orifice if you run it like this.

Thats my take, Im no expert but to me it makes sense to have ventilation to both heads.

[NC_John]

That schematic/plan does not allow for the evacuated crankcase air to be replaced with fresh air. Kinda necessary for the whole thing to work.

There is a ton of bad and contradictory info about this on ls1tech and other forums. I just gave up trying to figure it out and contacted a vendor directly for a setup.

[nsb29]

Originally Posted by NC_John

That schematic/plan does not allow for the evacuated crankcase air to be replaced with fresh air. Kinda necessary for the whole thing to work.

There is a ton of bad and contradictory info about this on ls1tech and other forums. I just gave up trying to figure it out and contacted a vendor directly for a setup.

The line that is marked green is your fresh air intake from your air cleaner

[sprint_9]

Originally Posted by NC_John

That schematic/plan does not allow for the evacuated crankcase air to be replaced with fresh air. Kinda necessary for the whole thing to work.

Originally Posted by nsb29

The line that is marked green is your fresh air intake from your air cleaner

nsb29 is right, your replacement air is the green line. Green line can be anywhere upstream of the throttle blade, so in the air filter pipe after the mass air flow sensor, or if your throttle body has a dedicated nipple like in the schematic.

[Steve Cole]

Originally Posted by sprint_9

From what I have gathered by reading and research is that a stock setup always pulls across the engine when venting. So for example, stock trucks pulled from an inlet on the passenger side valve cover across the engine to an outlet on the drivers side. Some of the cars pull from both valve covers and then out the valley. What needs to be accomplished is even ventilation of the engine, or as close as can be achieved.

I think this would be the best way to do it, and is similar to what Im planning on doing with mine. I would maybe consider enlarging the fixed orifice if you run it like this.

Thats my take, Im no expert but to me it makes sense to have ventilation to both heads.

You are absolutely right Sprint, in your diagram, the fixed oriffice (PCV) would change from an exhaust , to an intake. I found that diagram today and it made sense. That hole would definitely need to be enlarged though. Do you think there is a way to remove that metered oriffice and replace with a straight tube for similar airflow as the passenger side valve cover? Thanks.

[NC_John]

My bad - thought that was representing the tb, and was after. Didn't catch it was the MAF.

[nsb29]

Originally Posted by sprint_9

nsb29 is right, your replacement air is the green line. Green line can be anywhere upstream of the throttle blade, so in the air filter pipe after the mass air flow sensor, or if your throttle body has a dedicated nipple like in the schematic.

I thought that was the air cleaner LOL but doesn’t the fresh air Green Llne have to be before the mass airflow sensor Not the throttle plate

[A1971Blazer]

I am setting up the PCV on my LS1 similar to this picture without the PCV valve....just the little short curved hose that goes right back into the intake.
I got the later LS6 valley cover that has the valve built in...I'm going to try it without the catch can....

[Steve Cole]

Hey Blazer,

Did your engine originally have the PCV (or metered orifice) on the rear of the driver side valve cover? What are you going to do with that?

[A1971Blazer]

Originally Posted by Steve Cole

Hey Blazer,

Did your engine originally have the PCV (or metered orifice) on the rear of the driver side valve cover? What are you going to do with that?

I'm sure it probably did....there was a bunch of stuff I pulled off and put in a box...and I just plugged that hole....but I will look to see if I still have it...

Just be aware I'm not offering it for sale in this post or I'm not considering your question as a "want to buy" either...just so the "powers that be" do not mis-interpret it as such...

I will PM you with details if I can find it...

[Steve Cole]

Yea, I wasn't trying to buy anything from you, just curious if you were going to plug it or use it since now you have 2 PCV's (or metered orifices, however you look at it). The LS6 cover is one, plus the original one in the drivers VC.

[sprint_9]

Originally Posted by Steve Cole

You are absolutely right Sprint, in your diagram, the fixed oriffice (PCV) would change from an exhaust , to an intake. I found that diagram today and it made sense. That hole would definitely need to be enlarged though. Do you think there is a way to remove that metered oriffice and replace with a straight tube for similar airflow as the passenger side valve cover? Thanks.

I assume it can just be drilled out to a larger size. Take the valve cover off, drill it or see if it pops out then blow any debris out of it. I think it's cast into the valve cover but it's been awhile since looked at one.

Originally Posted by nsb29

I thought that was the air cleaner LOL but doesn’t the fresh air Green Llne have to be before the mass airflow sensor Not the throttle plate

For fresh pcv intake I think it's best to be downstream of the mass air flow, and it has to be upstream of the throttle blade, if it is not upstream of the throttle blade then your under the same vacuum as the dirty side of the pcv system. Some throttle bodys have a nipple that is ported to infront of the throttle blade. Air after the mass air flow has been metered by the sensor, you want this fresh air metered as when it works through the system it ends in the intake and is eventually used in the combustion process.

[A1971Blazer]

Originally Posted by Steve Cole

Yea, I wasn't trying to buy anything from you, just curious if you were going to plug it or use it since now you have 2 PCV's (or metered orifices, however you look at it). The LS6 cover is one, plus the original one in the drivers VC.

I understand..that wasn't actually meant for you..I had a couple of other posts that someone mistook for a sale post that actually wasn't...

anyway, yes I am just gonna plug that hole in the driver's side VC and call it good...

[AustinBelair]

I have this same setup and it's connected but I have an LS2 throttle body without a provision for PCV

[71cadc10]

the way the cars get hooked up with LS6 valley covers:

your "dirty air"
run line from valley cover to catch can
line from catch can to intake (manifold vac, after TB blade).

your 'clean air'
line from pass side valve cover, to intake tube or port on the TB (ahead of TB blade).
driver side valve cover is capped. The cars had a rubber cap placed on the nipple.

so the only place air pulled in was thru the passenger side cover.
Catch can is a great idea, cause the cars with LS6 valley often pull a lot of oil into the intake. it will literally be dripping out of the intake ports when you remove a plastic intake from a LS6 or LS2 car engine from those years 2002 to 2006 or so.

[Steve Cole]

Originally Posted by 71cadc10

the way the cars get hooked up with LS6 valley covers:

your "dirty air"
run line from valley cover to catch can
line from catch can to intake (manifold vac, after TB blade).

your 'clean air'
line from pass side valve cover, to intake tube or port on the TB (ahead of TB blade).
driver side valve cover is capped. The cars had a rubber cap placed on the nipple.

so the only place air pulled in was thru the passenger side cover.
Catch can is a great idea, cause the cars with LS6 valley often pull a lot of oil into the intake. it will literally be dripping out of the intake ports when you remove a plastic intake from a LS6 or LS2 car engine from those years 2002 to 2006 or so.

I thought that was the whole point of the LS6 valley cover, it pulls from an area where it doesn't collect nearly as much oil as it would if you pulled from the valve cover.

[71cadc10]

it still collects a lot of oil....pulls it right into the intake.
a catch can in line between LS6 valley cover and the intake, will help a lot

[solidaxel]

Following for updates

[Steve Cole]

Quick update: I did buy a catch can and mounted it with a simple bracket. The location allows it to tuck neatly under my 3 piece engine covers without interference. I plan to use the LS6 valley cover and the can together exactly like 71cadc10 described and see how that works. I would still like to pull fresh air through BOTH valve covers but GM didn't do it that way so I am not going to either (for now). Anyway, here is a link to a YouTube review of the catch can I bought. https://www.youtube.com/watch?v=FjsJWChNrI0

[sprint_9]

Originally Posted by Steve Cole

Quick update: I did buy a catch can and mounted it with a simple bracket. The location allows it to tuck neatly under my 3 piece engine covers without interference. I plan to use the LS6 valley cover and the can together exactly like 71cadc10 described and see how that works. I would still like to pull fresh air through BOTH valve covers but GM didn't do it that way so I am not going to either (for now).

I thought about this in relation to my situation as well and came up with the same conclusion. I was under the impression that all of them pulled across the motor in a cross pattern, but obviously that isnt the case, I think most of them did the cross pattern, but not all as has been pointed out. Im going to run my setup in the same fashion, in the passenger valve cover, out the valley to a catch can and then into the intake.

I have to say Im looking forward to not having to run another hose or drill into my valve covers, Im running out of room to tuck stuff neatly away.