PCV Oil Catch Can on N/A 5.3 fills FAST...
02-05-2010, 11:11 AM
#41
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The hose from the PCV valve on the valve cover goes to the inlet on the catch can. the hose from the outlet on the catch can goes to the nipple at the center of the intake.
02-05-2010, 12:16 PM
#42
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how does water and oil get in the catch can?Is it from the intake side? I just didnt understand the water with oil issue.
Also can you not put a inline check valve, with one way flow, instead of a catch can?
Just thinking i might install inline filters or check valve instead of catch can!
Does the PVC valve have to be connected to the intake in order to function properly- 01 LQ4
Also can you not put a inline check valve, with one way flow, instead of a catch can?
Just thinking i might install inline filters or check valve instead of catch can!
Does the PVC valve have to be connected to the intake in order to function properly- 01 LQ4
Last edited by HDSIERRA; 02-05-2010 at 04:01 PM.
02-05-2010, 04:06 PM
#43
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A PCV valve IS a one way check valve(it can become two way in the unlikely and rare chance that a backfire occurs). GM and some of the other brands are now using what they call a fixed orifice PCV, but it doesn't have a pintle or a spring. I guess it's more like a venturi. The oil and water come from the crankcase. Moisture is condensed in the crankcase when the engine cools down after sitting overnite. This oil and water mist is trapped in the catch can when air flowing through the crankcase(air enters Bank2 upstream of the throttlebody) is pulled into the intake manifold under vacuum. Without a catch can this oil and water mist enters your intake manifold coating it sort of like thick cough syrup does your throat when you have a cold. Add to that the tar and soot from an EGR valve and dirty and debris particles than get in when you don't change your air filter regularly and you have a real mess on your hands. Got to love the EPA for all these "bright" ideas. If you live the the desert where humidity is low you're probably going to see mostly oil in the catch can and very little water.
Last edited by eallanboggs; 02-05-2010 at 05:44 PM.
02-05-2010, 05:06 PM
#44
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You're saying just changing from 5-30 to 10-40 has a dramatic change on oil flow out of the PCV? That's interesting. How large is your catch can that it would fill in 100 miles. I bought a small air compressor water seperator at Harbor Freight for $7.99 and installed it. I ran 700 miles to Houston over the weekend and had about 2 tablespoons in it when I got back. Engine is low mileage. It was oil and water mixed.
11-15-2011, 02:11 PM
#45
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I'm still trying to understand this "fixed orifice" thing. I thought the variable orifice was there for a reason. GM isn't the only one using the fixed orifice on the valve cover. There must be a maintenance interval to remove the rocker cover to clean the PCV inside because it will eventually get gunked up.
How would clogging the hole help the engine suck oil up into the manifold?
11-15-2011, 07:35 PM
#46
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If it gets clogged flow stops and that ain't good for crankcase ventilation. Oil isn't supposed to get into the intake. That's what the catch can is supposed to prevent. The variable orifice is a one way check valve to allow flow into the intake, but not out of it. I've never seen mention of a cleaning interval, but you would think the thing would eventually fill with gunk and debris. These rocker covers are easy to remove if you have to clean the thing.
11-16-2011, 08:27 AM
#47
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If it gets clogged flow stops and that ain't good for crankcase ventilation. Oil isn't supposed to get into the intake. That's what the catch can is supposed to prevent. The variable orifice is a one way check valve to allow flow into the intake, but not out of it. I've never seen mention of a cleaning interval, but you would think the thing would eventually fill with gunk and debris. These rocker covers are easy to remove if you have to clean the thing.
It is a fixed orifice - basically, a hole. The engine uses vacuum to suck vapors out of the orifice. Now, years later, it is clogged. Wouldn't that mean nothing goes through the orifice, not vapor, not oil? I fail to understand how clogging up the hole could cause oil to be sucked into the intake.
11-16-2011, 08:41 AM
#48
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If it's clogged then yes nothing flows. Crankcase ventilation STOPS, but that also happens with regular PCV valves too if they aren't cleaned or replaced. I've never seen the guts of a fixed orifice PCV so I don't know the internals of it. If it's fixed maybe that means it's not really a one way valve like your normal PCV valve. If you put an air nozzle on your compressor hose and blow compressed air into the fresh air inlet hose on the Bank 2 rocker cover you should be able to feel that pressure being relieved on the hose that exits the Bank 1 rocker cover(hose coming out of the PCV valve). If not you have a blockage which is most likely the PCV valve whether it's a fixed or variable orifice type.
11-16-2011, 12:33 PM
#49
There are no guts in the fixed orifice PCV valve, it's just an empty valve with a hole that engineers calculated to be a certain size that will allow for good crankcase ventilation while also decreasing oil consumption in to the intake. I can tell you from my experience, it doesn't work. I used to have a home made catch can, and I switched from my original spring and plunger pcv valve to the updated fixed orifice pcv valve, and the amount of oil collecting in the catch can didn't change one bit. So that's where I got my conclusion that the fixed orifice valve doesn't do diddly.
Funny thing, when I installed my AMW catch can, it had a nasty whistle while the engine was running. I called up AMW and the first thing the guy said was "are you runnin a fixed orifice pcv valve?"
So I put my original pcv valve back in and the noise went away. I just hope that they don't stop making the original since it's been "counter measured", as I plan to keep using that style of PCV 
Funny thing, when I installed my AMW catch can, it had a nasty whistle while the engine was running. I called up AMW and the first thing the guy said was "are you runnin a fixed orifice pcv valve?"
So I put my original pcv valve back in and the noise went away. I just hope that they don't stop making the original since it's been "counter measured", as I plan to keep using that style of PCV
11-17-2011, 08:34 AM
#50
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Did you install the catch can because of smoke at start up? Did it fix it?