Oil catch can

[HSKR R/T]

If the can (hence the line) is clogged it will definitely increase crankcase pressure, as it is a closed system and the pressure has nowhere to go except eventually out the seals. The intake side doesn't matter on a N/A if its sealed or not, its actually better if it is sealed like old style engines that also vented crankcase pressure directly to atmosphere. The intake side on N/A is always a vacuum when running. Actually considering a new can with a vent to atmosphere to avoid this situation. Fundamentally I had the same situation as a stuck closed PCV valve. Its not good, hence the idle issues.

That's not how the PCV system works. I suggest you do a little more research on it. By "intake" I mean the air intake from air box to throttle body. There should be zero vacuum on that.

 

[A-TEAM]

Ive done all the research I need to do. I know how it works, and it works exactly how I explained it, hence my success in fixing said system and fixing my idle issues. If you have more to add about how it functions, please share what you know.

 

[Namelama]

Hi, I'm considering installing an oil catch can. What is a good brand that's easy to maintain empty and clean?

Easiest thing I've ever installed.

Oil Separator | Oil Catch Cans for Mopar Vehicles

Discover J&L OSC oil catch cans/oil separators for Mopar engines. Built for Dodge, Chrysler, Jeep, and Ram to protect your engine. Shop today.

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[mikeru82]

Easiest thing I've ever installed.

Oil Separator | Oil Catch Cans for Mopar Vehicles

Discover J&L OSC oil catch cans/oil separators for Mopar engines. Built for Dodge, Chrysler, Jeep, and Ram to protect your engine. Shop today.

www.jlosc.com

My main concern with that catch can is the small capacity. It only holds 3 oz of liquid. I hope you’re planning on checking/emptying it often, especially in winter months.

 

[HSKR R/T]

Ive done all the research I need to do. I know how it works, and it works exactly how I explained it, hence my success in fixing said system and fixing my idle issues. If you have more to add about how it functions, please share what you know.

The PCV valve is connected to the intake manifold and has the vacuum on it. The other hose that connects to the intake tube(between air filter and throttle body, is fresh air inlet into the crankcase. There is no valve on that line. pCV is not "sealed". That tube not on the PCV valve side will vent to air is there is pressure in crankcase

 

[A-TEAM]

The intake hose side will vent, but not effective enough to reduce pressure as it is designed as a one way system, with flow going in, not out of that side. Even the small amount of venting that happens when the valve side is clogged/ stuck closed will saturate the intake tube and TB with oil vapor, and run positive pressure in the crankcase, causing further problems. The system is designed for the crankcase to have slight vacuum, never positive pressure. When I was referring to a closed system, I mean the pcv valve side plumbing where the catch cans are tapped, that is a closed loop from valve cover to the intake port. Block off that hose with a clamp, stuck pcv valve or in my case, a clogged catch can and the hemi becomes very upset because she cant breathe properly. Poor idle is the first sign, but left unfixed can cause serious issues with gaskets because that pressure and oil vapor has no where to escape and will eventually find a path through a valve cover gasket, main seal, etc.

 

[HSKR R/T]

The intake hose side will vent, but not effective enough to reduce pressure as it is designed as a one way system, with flow going in, not out of that side. Even the small amount of venting that happens when the valve side is clogged/ stuck closed will saturate the intake tube and TB with oil vapor, and run positive pressure in the crankcase, causing further problems. The system is designed for the crankcase to have slight vacuum, never positive pressure. When I was referring to a closed system, I mean the pcv valve side plumbing where the catch cans are tapped, that is a closed loop from valve cover to the intake port. Block off that hose with a clamp, stuck pcv valve or in my case, a clogged catch can and the hemi becomes very upset because she cant breathe properly. Poor idle is the first sign, but left unfixed can cause serious issues with gaskets because that pressure and oil vapor has no where to escape and will eventually find a path through a valve cover gasket, main seal, etc.

Or through the other side of the PCV system that is normally the in side of airflow. You can replace that tube with just a breather filter and plug the nipple on the air box lid. And it will vent to atmosphere even if you cap the PCV valve. Which is also why a vented catch can doesn't work and will cause idle issues. Because you are basically just creating a vacuum leak.

Also, it's called "positive" crankcase ventilation, not negative.

 

[A-TEAM]

“Positive” doesn’t mean pressure, it means forced ventilation, as opposed to passive venting like you are describing. The system uses vacuum as a method for “positive” control. A passive vent to atmosphere will reduce pressure and save the gaskets for sure, but a lot of the blow by and vapor would stay in the oil and contaminate it quicker. Hence the positive system.

 

[HSKR R/T]

“Positive” doesn’t mean pressure, it means forced ventilation, as opposed to passive venting like you are describing. The system uses vacuum as a method for “positive” control. A passive vent to atmosphere will reduce pressure and save the gaskets for sure, but a lot of the blow by and vapor would stay in the oil and contaminate it quicker. Hence the positive system.

So of the PCV valve is using vaccum to suck vapors out of the crankcase, where is the air coming from that goes into the crankcase as the PCV evacuates it? Also, PCB valve only works when the intake manifold is under vacuum, which it doesn't have at wide open throttle. When any blowby would be the highest. Based on your description, the engine would blow out every seal because there would be no vacuum to suck out the pressure.

PCV is an emissions control system. It is meant to reduce the amount of vapors out of the crank case from escaping to atmosphere. But you can't have just an open line to the intake manifold because that is basically an unmetered vacuum leak and would mess with your A/F ratios. Hence the PCV valve to meter the amount of air. Otherwise you could just run dual breathers and vent everything to atmosphere, which a lot of race cars do. It's also the reason the fresh air inlet side is connected to the intake tube before the throttle body, so any vapors that might get pushed out that side, under higher crank case pressure at WOT, are cycled back through the cylinders. It's also why, on our trucks, there is the secondary carbon filter in he air box lid to absorb any of these vapors that might leak out after shutting the engine off. There isn't a valve on that side of the PCV system so crankcase vapors can escape out that side. It's also why boosted cars run vented catch cans on that side of the system to prevent the vapors from getting into the engine as boost pressure builds and forces them out the breather side when the PCV valve can't flow enough.

But go on and keep thinking the PCV valve itself is to prevent crankcase pressure.

Heres a good video to help you out.

 

[A-TEAM]

Lets keep the discussion focused on PVC system because passive systems are completely different in design and function and don't apply here. To answer your first question, the air is being supplied via in inlet tube side. Now answer this; if the PCV valve side is blocked or restricted to the point where the crankcase is venting thru the intake tube, where is the air coming from to balance that out?

This must be viewed as a complete system, both intake and scavenge side must be open and working. As an experiment, clamp off one of the hoses on your catch can and observe how the engine runs.

 

[HSKR R/T]

Lets keep the discussion focused on PVC system because passive systems are completely different in design and function and don't apply here. To answer your first question, the air is being supplied via in inlet tube side. Now answer this; if the PCV valve side is blocked or restricted to the point where the crankcase is venting thru the intake tube, where is the air coming from to balance that out?

This must be viewed as a complete system, both intake and scavenge side must be open and working. As an experiment, clamp off one of the hoses on your catch can and observe how the engine runs.

You just countered your own argument. Good job. It's still an emissions system meant to keep the vapors inside the engine, and not venting to atmosphere.

 

[A-TEAM]

Since you didn't bother to answer my question, ill answer it for you. The replacement air is coming in thru the same tube that it is venting from. That is why it is not efficient and still will build pressure. At this point Im not sure what youre trying to articulate here? That having a stuck pcv valve or clogged line is just fine and no big deal?

 

[HSKR R/T]

Since you didn't bother to answer my question, ill answer it for you. The replacement air is coming in thru the same tube that it is venting from. That is why it is not efficient and still will build pressure. At this point Im not sure what youre trying to articulate here? That having a stuck pcv valve or clogged line is just fine and no big deal?

As long as the fresh air side isn't blocked, the only issue you will have is oil/fuel vapors being pushed out the tube into your air box(if running factory air intake). The PCV system is to evacuate the vapors created by blowby and the combust process and cycle them back through the cylinders to keep them from going to atmosphere. Otherwise they would just run bresthers on the valve covers. But it's an EPA mandated system. You can clamp he catch can lines off all day long and not cause any issues with how the engine runs, as long as the other side is still free flowing. It's not a "sealed" system. It literally sucks in fresh, outside, air when intake manifold is under vacuum. and if crankcase pressure is too high, it will push air back through that same fresh air line. You aren't going to blow engine seals if you PCV valve fails as long as the other half of system is still open.

Once again, there is no flow control valve on the fresh air intake side to prevent crankcase pressure from pushing the air out that same side.

 

[HSKR R/T]

Since you didn't bother to answer my question, ill answer it for you. The replacement air is coming in thru the same tube that it is venting from. That is why it is not efficient and still will build pressure. At this point Im not sure what youre trying to articulate here? That having a stuck pcv valve or clogged line is just fine and no big deal?

As far as "replacement" air, if the PCV valve is blocked, there is no air being sucked out by vacuum to need "replacing". At that point, it's the blowby pressure pushing vapors out the normal "intake" line. Saying the air has to come in through the same line it's venting out of it rediculous.

 

[A-TEAM]

If there is only one way in and out the pressure has to equalize to atmosphere somehow, if air is being pushed out, then its getting sucked back in when it equalizes. If the engine breathes just fine with one side clogged then why are the air:fuels all thrown off with a poor idle side effect?

 

[HSKR R/T]

If there is only one way in and out the pressure has to equalize to atmosphere somehow, if air is being pushed out, then its getting sucked back in when it equalizes. If the engine breathes just fine with one side clogged then why are the air:fuels all thrown off with a poor idle side effect?

There isn't only one way in and out.

Do you understand what blowby is?

If blowby pressure is causing vapors to be pushed out of the breather (what I will call the fresh air side of PCV system going forward), thats the equalization you are looking for. There doesn't need to be anything "sucked" in, because it's being forced in by compression through the piston rings.

Have you monitored A/F ratios with a wideband sensor to verify fuel ratio is being effected by a blocked PCV valve? Or is that something you came up with to try and justify your opinion?

 

[A-TEAM]

Just narrowband with the Diablo Trinity, im just going off real word results here. Clogged line > poor inconsistent idle indicating unstable air:fuel. Open line > idle normal. My point of posting was to let others know what I fixed and how I did it, not to get into a drawn out debate about PCV systems and how they work when they are not working correctly with clogged lines. So thank you sir for the knowledge you have shared about the subject. Im going to go pull my intake to make sure no residue n there.

 

[RebelliousGt]

Well I am here to report back on my catch can setup giving me some drama. Noticed my idle was starting get get rough, ran some seafoam thru the fuel system, cleaned the TB real good, no changes. Traced it to the PCV system. Started exploring and found my mishimoto catch can system was clogged up pretty good. Very difficult to blow air thru it. Took the can completely apart and cleaned everything and narrowed it down to the “filter” media. Soaked it a few times in solvent which helped but it was still more difficult to blow thru than I am comfortable with. So for now I drilled a 1/8” hole thru the media and air goes thru with no resistance now. Probably cut down the efficiency of the can significantly but I don't want to start blowing seals with too much crankcase pressure. Put it all back together and put a new PCV valve in for good measure (88k) and now my idle is perfect again. Heads up to anyone with a rough idle, check the pcv system and catch can!! Now to see if I can buy replacement media part from mishimoto. Pic is what the part looks like, its the gold part. (without my hole mod)

Odd I’ve had no issues with mine for over 3.5 years, even after winter time chocolate milk mixtures with water in it.

 

[RebelliousGt]

This is summer time catch

 

[RebelliousGt]

These are at only 8,000 km of driving at oil change intervals