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My catch can fills completely with oil in probably 20 minutes of driving. (NA 383 LS1, Heads/Cam, Intake)
I have the dirty side coming off the drivers side PCV valve.. routed to the lower port on the EliteEngineering can, and I have the top port connected to the Fast Intake behind the throttle body. Currently have one port blocked and rear port with a small breather for fresh air on passenger valve cover.
Can anyone help me account for why it’s filling like this? No significant blow by with the oil cap removed etc. It didn’t matter which way I had the lines connected at the can it fills up WAY fast.
Probably the valve cover. The baffles in those have been improved substantially over the years.
Replace them with the Dorman ones, which have the better baffles.
Your truck will probably run AHELLUVALOT better - especially at idle - if you do away with the "breather" and instead drill a port into the intake tube between the MAF and the throttle body, and hook the pass side port up to that instead.
Probably the valve cover. The baffles in those have been improved substantially over the years.
Replace them with the Dorman ones, which have the better baffles.
Your truck will probably run AHELLUVALOT better - especially at idle - if you do away with the "breather" and instead drill a port into the intake tube between the MAF and the throttle body, and hook the pass side port up to that instead.
That would be a nice remedy! Can it really pull THAT much oil with the unrevised valvecover?
Is there another method I should consider? No catch can somehow?
The intake manifold is doing a mighty fine job of sucking oil into the catch can. I wouldn't be surprised if some of that oil has even made its way into the manifold. I suggest that you do away with the sealed catch can, cap off the intake manifold and connect that line off the valve cover to a breather can. 3/8" hoses would be on the small side for my likes but I bet it would 100% solve your problem. I'm in agreement with changing the valve covers, especially if those are the LS1 valve covers.
Here's a picture of a set of LS1 valve covers and the factory line that connects the two valve covers to the intake manifold. Biggest problem with these are is the baffling in them not to mention the size of the hole on the driver side valve cover. Being that it's at the back of the engine I can easily see the intake sucking in oil from this. I've also attached a picture of the hose connector that came off my LS1. Notice the PCV valve at the end of the line that would connect to the 3/8" hose that's on the intake manifold port? If you was going to use this type of setup with a sealed catch can like the one you have you would need to remove the little breather of the rear port of your passenger valve cover, remove PCV valve at the end of the line shown and connect that line to the top of a sealed can. Then run another line coming out of the can through an inline PCV valve that's between it and the manifold. The last thing to do would then be to run a hose from the front port of the passenger valve cover to the elbow of the air intake tube between the MAF and the TB.
Here's a picture of a set of LS3/LS7 valve covers where I removed the 3/8" ports then drilled and tapped for 3/8" NPT and installed 3/8" NPT to 10AN male bungs and connected the two valve covers to the Moroso breather can. The intake manifold and throttle body was capped off.
Hope this gave you some insight on how to resolve your issue..
Last edited by 01CamaroSSTx; May 29, 2026 at 05:26 PM.
Thanks guys. I think I’ll try the breather can set up.
Is best I can tell even if it’s set up correctly it is absolutely pulling a massive amount of oil out of that valve cover so unless I can restrict how much vacuum it’s pulling on it it’s just gonna create a problem I
Thanks guys. I think I’ll try the breather can set up.
Is best I can tell even if it’s set up correctly it is absolutely pulling a massive amount of oil out of that valve cover so unless I can restrict how much vacuum it’s pulling on it it’s just gonna create a problem I
The Mighty Mouse can acts as a pcv valve. Most of what I get in my Mighty Mouse can is mostly a fuel and water mix with just a little oil. I have the updated Dorman valve cover on the driver's side and the stock LS1 valve cover on the paseenger side.
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Catch Can fills with Oil 
