Whos' running a catch can?

[BR3W CITY]

I've never had oil blowby problems, but I have an extra tank laying around and figured I'd use it as a catch can.

Right now I just have the regular 2 lines for the pcv system on my lq4 (one from ps valvecover to TB, and the other from DS valvecover w/ the PCV to the top of the intake). I've seen probably 10 different diagrams, some running breathers, others with exhaust evac, others running the manifold vacuum...too many choices.

What have yall used?

[homemade87]

Let me tell you what I found out for myself . I have a ls2/ls3top end that is carbed . I decided to get a ls6 valley cover that has the pcv sticking out the front of the cover . What I did was pulled vacuum from the valley cover to the intake . On the valve covers I added a small 2" filter on the left and the right valve covers . This will be the air intake into the valve covers . What this did was pull air in the valve covers thru the head to the crank case and up to the valley cover and out .

I have lost zero oil with this set up . At lease no measurable amount . Ok , why I think this works . The factory system from the valve covers is pulling vacuum out from the valve covers . There is a lot of suspended oil in there from the rockers slinging it around so the vacuum is picking it up and putting it thru the system . With the way I have it the there is little to no suspended oil in the air at the valley cover .

I also have a ls2 in my 82 and has the classic oil in the intake problem . I am planning on doing a performance head change and when I have it apart I plan on installing a ls6 valley cover and doing the same thing .

From my experience I would recommend spending that $100.00 on a valley cover and a couple small filters for the valve covers instead of the catch can . This way is also no maintenance and keeps the engine bay less cluttered .

If you plan on installing the catch can don't expect it to work perfect . The can will catch some of the oil but there will still be some get by the can . I have a couple friends and have experienced this .

I had did some looking around on some other forums on this subject and others had had good success with the ls6 cover .

Just wanted to share my experience with this oil problem .

[dec010974]

hit me up BR3W CITY. ill post pics when I get a chance. I can text them to you. my oil blow by, was so bad that the excess oil burned, and made it, all the way thru the exhaust. This what I did. I plugged everything on the intake manifold except for the Transmission modulator line that provides vacuum for the TH400. I have a DBC setup and the port on the throttle body, that leads to the passenger side valve cover was plugged. the port on the passenger side valve cover is connects to the catch can. the port on the driver side valve cover is connected to the catch can. the catch can has a breather with a breathable filter. as of yet, I haven't had to drain the catch can. I haven't driven the c10 much either. I also gotta say that the white smoke, oil burning cleared up immediately. the tuner says sometimes, LSx engines suffer form too much vacuum, and creates all sort of breathing problems, and the fact that, we modify the smog and pollution equipment to fit our performance needs.

[Daaaanz67]

Hart Rob does read some of his threads.

[solidaxel]

I am watching this because I have a question on the passenger side valve cover hose and the port behind the throttle body.
Just waiting to see if I need a catch can like Br3w

[clinebarger]

LS6 Valley Cover here also, The 2nd design Fixed Orifice Style part# 12577927.

The cover has a built-in oil separator that seems to work very well.

[dec010974]

here are the pictures of the catch cans I bought of the bay. I used the round one because it was easier to set up/mount off of the heads. here is also a pic of line I ran to the catch can from the driver side valve cover. I'm having problems loading all the pics.

[Andy4639]

How do you know you need one of these????

[68GMCCustom]

you need one! I run one on both my truck and my TBSS... and every time I run one WOT it makes another little deposit in the canister rather then burning it down the intake. Mine are just simple little aluminum canisters with an internal oil separator and the rest is oil storage...just an in and an out line w/o a breather. Empty every 3k-6k miles or as required.

[Andy4639]

Originally Posted by 68GMCCustom

you need one! I run one on both my truck and my TBSS... and every time I run one WOT it makes another little deposit in the canister rather then burning it down the intake. Mine are just simple little aluminum canisters with an internal oil separator and the rest is oil storage...just an in and an out line w/o a breather. Empty every 3k-6k miles or as required.

68GMCCustom, That didn't tell me anything. Not being smart just want to know why I need one. I haven't had any issues with it like it is. Well that I know of. On the power tour in 2014 I only used 1 qrt of oil on the whole trip.

[homemade87]

Originally Posted by Andy4639

68GMCCustom, That didn't tell me anything. Not being smart just want to know why I need one. I haven't had any issues with it like it is. Well that I know of. On the power tour in 2014 I only used 1 qrt of oil on the whole trip.

Andy , Answer to your question is you dont really need one . Sounds like yours is a driver not a performance engine . What is happening is the pcv system is pulling oil out of the valve cover and running it thru the intake . You will not see any ill affects from it most likley . The engine will burn the oil . The thing I dont like is to have to monitor the oil all the time on my dailey driver that should not be burning oil ( 06 silverado ) . It can put thru it 1-1/2 quarts between changes . I have over 100,000 miles on the factory set up and no problems . Lots of these engines better that 200,000 on the factory pcv system with no problems . Its just most of us dont like to see that oil going thru the engine .

Now for performance its better not to have that oil in the combustion chamber . Diminishes performance , especially boosted . Can cause detonation .This is why you see most add the catch can .

Gm did come out with a second design valve cover that was better . It did not allow as much oil in the pcv system .


It will not hurt to put one on your engine if you want , but not nessasary for your set up . Just keep an eye on the oil level.

[Andy4639]

O thanks guy's that's what I need to know.
My truck is not a performance truck at all just a nice D/D.

[68GMCCustom]

Originally Posted by Andy4639

68GMCCustom, That didn't tell me anything. Not being smart just want to know why I need one. I haven't had any issues with it like it is. Well that I know of. On the power tour in 2014 I only used 1 qrt of oil on the whole trip.

I guess I should have explained clearer.....

I run one on both my truck and my TBSS... and every time I run one WOT it makes another little deposit in the canister rather then burning it down the intake.

I'm no Engineer so here you go.....Every time I punch it (my LY6 truck or my LS2 TBSS) on the entry ramps, or at a stop sign, or stoplight; and run it WOT thru 1st gear and part of second....(you know a typical little blast)...my current pcv system which includes a non vented catch can....the oil is sucked right past the factory baffle system and up a tube and into my catch can, rather then being sucked into the intake system and burned by my engine. Why does it matter? Others have mentioned various reasons its bad to burn...add that you might need to "de-carbon" the throttle body for an low/erratic idle issue related that could be related to a dirty MAF and/or...dirty throttle body that's made worse by bad oil control.

SO why? Basically because the stock oil baffle system in the valve cover doesn't hold the oil back well at WOT (and probably anything very aggressive)...meaning your motor gets to burn it...meaning issues.

[BR3W CITY]

Folks need em for a handful of reasons;

• the really early aluminum LS motors had some issues with oil consumption, and even some of the early iron block trucks had problems with the oil ring sealing.
• Most modern tight tolerance engines pass at least some oil, which because of the PCV system, get sucked into the intake manifold.
• Certain synthetic oils are functionally thinner than their advertised weights. LS motors in general don't love Royal Purple or M1 (huge discussion on its own, will need its own thread)

Naturally, any oil getting sucked into the intake can then get sucked into the combustion chamber, and burned. In addition, oil coating the inside of the intake can affect the Map/Tmap or any other sensors mounted within, as well as having some (though I'm not sure how quantifiable) change to the air's path.

Head/Cam cars can start to create additional levels of pressure in the crankcase, which if not properly dealt with can pop your diptstick out and make a hell of a mess. The additional pressure can also start to make the blowby worse at high rpm (watch some cars put black smoke or oil mist out at the big end).

Boosted cars PCV system works in the opposite way, but benefits the same way from giving the oil a place to collect that isn't the intake (or intercooler, as it were).

Some guys will just run breathers all the way around, which works on some cars but not as often on late model EFI. The guys who need a better catch can/pcv system are the ones with wet breather filters, or the guys running wristbands/socks around the breather and oil cap.

Another option is exhaust evac. This uses the exhaust velocity to create a vacuum draw on a piece of hose connected to your PCV. The vacuum helps draw clean air through from the topside, and sucks the oil vapors out and through the exhaust. Its an oldschool way of doing it, and in most cases is fine on the street IF your car doesn't pass much oil....BUT technically you are misting oil out the exhaust. This means your bumper or fenders will tend to get dirty, you'll smell the oil from behind, and you risk misting anyone behind you (and please believe it does NOT go over well at car events or drag races to be wizzing oil out your tailpipe).

Again, you don't NEED one, but some vehicles may all benefit from slightly different reasons.

[Custom 68]

I need to add one.

[dec010974]

ok lets try this again. this is how I installed my catch can. I bought (2) catch cans. I'm using the round one for convenience. it was easier to mount. the driver side valve cover, has a line, that runs from the rear, driver side valve cover, around, under the throttle body, close to the steam lines, to the catch can. the passenger side valve cover line runs to the catch can. the catch can has a breather. I hope this helps.

[dec010974]

I hope that helps. I have a pic that shows the path of the drive side catch can line that runs parallel to valve cover, but I cant find it. good luck to all.

[crazy longhorn]

BREW, I am running a stock bottom 5.3, the old boich is carbed....140,000 on the bottom, heads are fresh. Pressure test/ surface/ grind/ blue springs/ ARP bolts/mtl gaskets. She don't blow no "blues', or stink of oil, out the pipes? No restictor....old school, she is running a pcv valve. The vac guage on the dash pulls 23 inches (steady) My 1st trip, into the LS....not done playing yet longhorn

[dec010974]

crazy longhorn, can I see pics of your set up. I sold my carbed stuff and we to the FI side. I couldn't tune worth a damn. I don't know much about carbs or the MSD ignition box.

[BR3W CITY]

Originally Posted by crazy longhorn

BREW, I am running a stock bottom 5.3, the old boich is carbed....140,000 on the bottom, heads are fresh. Pressure test/ surface/ grind/ blue springs/ ARP bolts/mtl gaskets. She don't blow no "blues', or stink of oil, out the pipes? No restictor....old school, she is running a pcv valve. The vac guage on the dash pulls 23 inches (steady) My 1st trip, into the LS....not done playing yet longhorn

Where is your PCV feeding with the carb? Into the manifold, or the carb-base or??