Really looking to weigh some pros and cons here.

Plan to tackle some maintenance and give my G (150k) some TLC this weekend. Want to clean the throttle body and intake plenum (and maybe install my spacer), but got to thinking... If I'm going to spend the effort cleaning things up, I'd like to do what I can to keep them clean for as long as possible. I'd like to eliminate blowby making it back to the TB and intake plenum all together, but I assume there are some cons associated with a system that achieves that.

1) Catch Can - systems I've seen generally have one end hook up where the PCV valve was, and the other end hooked up to the intake plenum inlet at the front of the engine. The line running between the intake tube and intake plenum inlet at the back of the engine remains.

Pros: ease of emptying the can as needed?
Cons: depending on the quality of the catch can, the blowby could still find it's way into TB and plenum.

2) Open Breather - don't know that I fully understand these setups. Breathers go where the PCV valve was. Breather also installed on the intake plenum at the back of the engine. Caps are installed on the intake plenum at the front of the engine and the intake tube. Breathers allow excess pressure to be vented from the crankcase. The system is passive since there's no vacuum actively pulling blowby out of the crankcase.

Pros: elimintes blowby making it's way back into the intake system.
Cons: not emissions compliant. Breathers need to be cleaned/replaced periodically as I imagine they get mucked up with the blowby.

Again, looking to weight some pros and cons. Interested in hearing the reasons why people go one way or the other with their PCV system.
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A closed PCV system you take the hose between the PCV valve and intake manifold and install a catch can.

A vented system you still use the catch can but you plug the hole in the intake, you also take the hose from the intake pipe and route it into the catch can (plug the hole in the intake). On the catch can outlet you install a breather filter, typically you would also remove the PCV valve and either drill it out to remove the valve, or replace it with a threaded adapter since having the one-way valve is pointless (you could leave it though but most people just delete the valve).

Pro's for a delete/vented system
-No oil vapor going into combustion chamber
-Clean intake manifold

Con's for a delete/vented system
-Potential fines for deleting emissions equipment
-Cannot pass vehicle inspection for registration in some states/counties
-Makes an oily mess in the engine bay since that vapor sticks to EVERYTHING.

If you leave it as a closed system the benefit is you will trap SOME of the oil vapor going to the intake tract, better than nothing. As long as the rest of your engine is in good working condition it's not going to affect the engine too much unless you have a really hot tune with a lot of timing. If you are really pushing the limits of timing advance or if you are running any kind of forced induction then you definitely want to do a PCV delete so you aren't accidentally leaning out.

 

I personally went with a closed system baffled catch can and also stuffed a stainless steel scouring pad into it. Works great and traps a lot of oil.

 

Have to empty it more. It collects water too and it can be pretty full.