Catch Can Question
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 34,903
Likes: 12,326
From: NE South Carolina
If you get a 2 outlet can and plug one outlet (as I did) and only use the original OEM connections you don't need a check valve. The OEM hose you're replacing does not have one. IMO it only adds a flow restriction besides not being needed.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 34,903
Likes: 12,326
From: NE South Carolina
For what it's worth. You only need a check valve if getting and using the two outlet can. The check valve is used on the outlet going to the drilled hole in the air intake before the throttle body. That stops flow from that outlet thru the can to the OEM connection.
If you get a 2 outlet can and plug one outlet (as I did) and only use the original OEM connections you don't need a check valve. The OEM hose you're replacing does not have one. IMO it only adds a flow restriction besides not being needed.
If you get a 2 outlet can and plug one outlet (as I did) and only use the original OEM connections you don't need a check valve. The OEM hose you're replacing does not have one. IMO it only adds a flow restriction besides not being needed.
If you add the 2nd line, you must have a check valve to prevent air from flowing from before the TB thru the "Can" directly to the intake manifold essentially defeating the purpose of the PCV system!
Last edited by JerryU; May 24, 2015 at 11:51 AM.
Burning Brakes
Joined: Jul 2011
Posts: 841
Likes: 72
From: NC
I went with the Elite Best and dual check valves on my '15 Z51. I figured if I was going to install the mod, why not spend a bit extra and cover all the potential problem issues?
By the way, my E2 Best Can seems to be catching about 1/2 ounce of oil per 1,000 miles (mild driving conditions). It sure is nice knowing that oil isn't being ingested.
By the way, my E2 Best Can seems to be catching about 1/2 ounce of oil per 1,000 miles (mild driving conditions). It sure is nice knowing that oil isn't being ingested.
Last edited by Rave; May 25, 2015 at 12:49 AM.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 34,903
Likes: 12,326
From: NE South Carolina
If the one going to the air intake hose clogged, not a big concern. Unlike the main line there will not be much crackcase blowby going thru that line since the air intake hose is always near atmospheric pressure not like the intake manifold when cruising, which is a vacuum sucking in the crackcase gases.
Last edited by JerryU; May 24, 2015 at 12:04 PM.
Dazed Confused & Verklemp
Joined: May 2008
Posts: 1,397
Likes: 109
From: Naples, FL & Clear Lake, IA
I have the UPR catch can with 2 outlets and the clean oil separator. Both exit lines have check valves midway between the ends. Their ends are the quick connect ones just like GM's. While I don't do long WOT runs (OK maybe I do when I'm at or practicing for my stripping!), but I didn't want any opportunity to get oil in my intake in a DI engine.
Don't understand why GM doesn't provide a remedy like Ford does on their 3.5TT DI engine where the oil is caught using the same system as aftermarket catch cans in one of the valve covers, and just runs back into the engine.
Don't understand why GM doesn't provide a remedy like Ford does on their 3.5TT DI engine where the oil is caught using the same system as aftermarket catch cans in one of the valve covers, and just runs back into the engine.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 34,903
Likes: 12,326
From: NE South Carolina
I have the UPR catch can with 2 outlets and the clean oil separator. Both exit lines have check valves midway between the ends. Their ends are the quick connect ones just like GM's. While I don't do long WOT runs (OK maybe I do when I'm at or practicing for my stripping!), but I didn't want any opportunity to get oil in my intake in a DI engine.
I'm just trying to define what it does and so far can't see a benefit in a non supercharged engine. Just sayn'!
Last edited by JerryU; May 24, 2015 at 03:52 PM.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 34,903
Likes: 12,326
From: NE South Carolina
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Safety Car
Joined: Jan 2015
Posts: 3,941
Likes: 499
From: Northern Virginia
Thread Starter
Drifting
Joined: Feb 2000
Posts: 1,591
Likes: 53
From: Central MN
Excellent discussion on this topic. I'm still not convinced, however, that a second exit or a clean air separator are necessary. Consequently, I went with the "good" can.
To me, a simple solution to the coking issue for GM is to install a catch can large enough to hold the estimated oil "blow by" between oil changes. Then, when the oil is changed, have draining the catch can part of the procedure. Heck, they could even run a drain line down near the current drain plug(s). If GM felt there was a need for a clean side separator, it could be added with no additional maintenance required.
To me, a simple solution to the coking issue for GM is to install a catch can large enough to hold the estimated oil "blow by" between oil changes. Then, when the oil is changed, have draining the catch can part of the procedure. Heck, they could even run a drain line down near the current drain plug(s). If GM felt there was a need for a clean side separator, it could be added with no additional maintenance required.
Safety Car
Joined: Jan 2015
Posts: 3,941
Likes: 499
From: Northern Virginia
I agree for base cars, but for forced induction motors I think the second exit may offer some benefit. If the dry sump tank is overfilled, significant amounts of oil can end up in the intake. If you always change your oil yourself, and are certain you'll never over fill, the clean side probably isn't necessary. But if you let dealers or others change your oil, it's probably cheap insurance.
Melting Slicks
Joined: Dec 2011
Posts: 2,690
Likes: 116
From: Richmond area Va
A second can or clean side can is only necessary when airflow of the pcv system reverses as crank pressures build (lack of vac or some cases presence of boost).
There are some cans that provide a large pressure relief right on the can to prevent this from ever happening
There are some cans that provide a large pressure relief right on the can to prevent this from ever happening