Breze84

So I have a proper Catch can routing question... I have a Forged H/C LS7 11.25:1, that uses a LS3 topend. I just recently had the car retuned and it was setup on Speed Density. The shop that tuned my car said I a PCV Vac leak because of my catch can / breather setup and having the wrong valley cover "LS6 Version"... So they changed my valley cover to a LS3/7 style and scrapped my catch can/breather. They ended up looping the PCV to intake like oem with a U-hose and drilled 2 holes on my airbridge. They ran a tube from my driver side rear to a hole on the airbridge, and ran a hose from my passenger side front to the other hole on my airbridge.

So, I pulled my TB off yesterday and noticed I had fresh oil puddled on the Throttle body blade opening, Buddy seen this and said they way they did it was wrong and It needs to breath so I dont blow my rear main seal because All I am doing is taking everything and just putting it back through my intake.

So my question is, If I go back and plug the holes on my airbridge, Cap the 2 nipples on my valve covers and scrap those 2 hoses. Pick up a oil cap with a -10 nipple and run that into my breather catch can and hook that up between the PCV and intake. Would this be sufficient or am I going to cause a Leak.

Or should I leave a normal oil cap on, Plug the holes that were drilled into my airbridge and take the 2 hoses from my valve cover and put those into the breather catch can and cap the Intake port and PCV nipple...

Any help would be appreciated, I just want to stop the oil, Vent everything properly without having a air leak ect....

Crap pic but this was with the catch/can breather setup before when I had a LS6 valley, Claimed PCV Vac leak



What It Looks Like Now

Breze84

Damn nobody

Last C5

Your suggested fix will probably work, but you're going to have to keep a close eye on the catch can to keep it from overfilling. You may need to dead head the driver's side nipple to a breather can in addition to your valve cap breather.

jerkyboy

I have a new LS-7 (wet sump with LS-2 pan) and I'm running into the same issue. The shop that installed the new motor removed my catch can that I had on my LS-6 and routed similar to yours. I believe the air in front of your TB is the clean air side and should go in to your VC's. The dirty air coming from the crankcase comes through the valley port and connects to the port in front of the intake. I think this location is where you would insert a can right? I think the valley cover port on the LS-7 has an integral pcv "restrictor under the cover. If you are using an LS-3 valley cover, I'm not sure it has one? If your catch can doesn't have a check valve, could that be a problem? I'm trying to figure all this out myself so this is really a bump to get the real experts in here.

The tuner I am getting ready to take the car to says I really need to have a catch can. He says he'd be concerned about excessive crankcase pressure building up. Not sure what that would have to do with a catch can. I'm afraid to vent my can and introduce un-metered air in to the system.

VGLNTE1

you should never have to vent a NA engine to the atmosphere. Your buddy saying your going to blow the rear main seal is quite wrong, and the shop ran it correct. If you take the pressure from the valley and route to intake, then it goes into the combustion chambers and out..not back into the motor. The reason you have oil in the intake is because there is no can between the valley and intake. You cant just have a hose connecting the 2. It will just pump oil into it. I hada to make my own set up and can for my 416 because those little catch can things they sell here are worthless for big cube, or built motor cars. Get a can between that line and its correct.

Breze84

So basically just a normal sealed can is what you are saying... Basic catch can...

VGLNTE1

With the proper baffles in it. There needs to be some media that catches the oil in the vapors and separates the air.

Breze84

Elite Engineering?

http://www.eliteengineeringusa.com/e...ing-catch-can/

VGLNTE1

I guess...those little ones didn't work for me. I ended up making my own that's a lot bigger, but its 100x better than just the hose that's there.

Breze84

What was the problem, I would upgrade the lines to something nicer

VGLNTE1

This is my motor, yours may be different, buy looks like you have cubes and more pressure. Which I have as well. But....mine would just go right though that weeny can and still right back in. Welding a bung on the valley with big AN hose then tap the manifold would be the best, but I just used a rad overflow can that's 15" tall and packed it full of media to block oil. Then another small filter between that and the intake. My intake is bone dry on the inside.

VGLNTE1

Maybe a off the shelf can is all you need. I'd Def try that first before going hog wild. I fought mine for years.

joerose

My drivers side nipple is already pluged with no catch can. is this right for a 2010 LS3 ?