2004 6.0 NV4500 Tahoe

[Dantheman1540]

There should be nothing in that circuit to filter out. The tube on the passenger side valve cover is a fresh air intake that draws it from the engine air intake tube. The circuit that has oily air in it is the port on the rear of the driver's side valve cover. There's a hose that runs from there to the top middle of the intake manifold. This air flows opposite of the one on the passenger side- the air flows OUT of the engine and into the intake manifold. You want to run a hose from the port on the valve cover to the inlet of the catch can, then from the outlet of the catch can to the port on the intake manifold. BE CAREFUL with the fitting on the intake manifold! It's plastic and will break very easily if you bend or twist it too much. I use a razor knife to slice the plastic hose on it lengthwise and peel it off. Then brace the fitting with my hand while I push on the rubber hose onto it, using a little lube to help it slide.

That's interesting I didn't know there was a fresh air intake for the valve covers. Seems to me it ends up being a second source of oil in the intake as the hose was full of oil when I removed it. I was planning to connect both sides to the can and eliminating the port on the top of the intake and having them both run back to the intake tube.

If one side is for fresh air then why do most people vent both valve covers to a single can then back to the intake? My Silverado has dual -10an to a single can then -10 back to the intake but also has the ability to vent to the atmosphere under heavy boost.

I will be extra gentle with that fitting I love old crumbly plastics.

 

[Rocket Man]

That's interesting I didn't know there was a fresh air intake for the valve covers. Seems to me it ends up being a second source of oil in the intake as the hose was full of oil when I removed it. I was planning to connect both sides to the can and eliminating the port on the top of the intake and having them both run back to the intake tube.

If one side is for fresh air then why do most people vent both valve covers to a single can then back to the intake? My Silverado has dual -10an to a single can then -10 back to the intake but also has the ability to vent to the atmosphere under heavy boost.

I will be extra gentle with that fitting I love old crumbly plastics.

That’s known as the “clean side” of the pcv system and some people run a clean side separator if you run WOT a lot or you find oil on that side. Also especially good for boosted applications. But you need a catchcan with dual inlets if you go this route. Info here:


Elite Engineering, the leader in Oil PCV Catch Can solutions announces the latest addition to their proven line of oil separating Catch Cans with the "Elite Clean Side solution".

The Clean-side solution addresses that small amount of oil vapor that enters the intake air charge upstream of the throttle body during WOT operation when the intake manifold vacuum is not present.

The Clean-side solution allows 100% MAF metered air entry while trapping the oil during wide open throttle operation and allowing it to return back into the valve cover as soon as the throttle is lifted.

Simply installs as a direct replacement for your stock Oil Fill Cap allowing you to delete and replace the stock OEM hose.

At 1/2 the cost of the plastic hollow GM unit, our aluminum clean-side separator incorporates an internal coalescing material. Simply unscrew the top for a quick inspection or cleaning.

Available in the most popular color Black, other GM colors are coming soon!

This is a direct replacement for your stock Oil Fill Cap. Comes with vacuum caps and fittings if needed to connect to your intake air inlet tube.

Models for both the V8 AND V6 GM engines.

 

[randeez]

That's interesting I didn't know there was a fresh air intake for the valve covers. Seems to me it ends up being a second source of oil in the intake as the hose was full of oil when I removed it. I was planning to connect both sides to the can and eliminating the port on the top of the intake and having them both run back to the intake tube.

If one side is for fresh air then why do most people vent both valve covers to a single can then back to the intake? My Silverado has dual -10an to a single can then -10 back to the intake but also has the ability to vent to the atmosphere under heavy boost.

I will be extra gentle with that fitting I love old crumbly plastics.

i dont think youll get enough vacuum going to the intake tube.

what vents to the atmosphere on your setup now, the catch can?

both valvecovers go to the can, can goes to intake and has a breather?

 

[Dantheman1540]

I'm not sure how I've never come across a "Clean air separator". So the clean air side has a check valve that is supposed to only let air into the valve cover correct? Is that check valve in the valve cover itself or is it a device attached to the intake tube or the hose between the two? Out of all the GM trucks I've had none have come with stock air filters or tubes so maybe I've never noticed one.

Randy- Yes the can has both valve covers vented to it and a single line routed back to the intake as well as an air filter on top to allow atmosphere venting. It is the Mighty Mouse Draft can and supposed to help with the smell of the PCV through the filter on the catch can during normal driving. The theory is that the vacuum during normal driving is enough to pull the small amount of vapors being vented and stopping it from smelling bad. During WOT when a lot of crankcase pressure is being vented it allows whatever the engine cannot consume to vent to out the filter. My previous setup was both covers vented to a can that vented to the atmosphere and I could smell the vapors all the time.

 

[Rocket Man]

I'm not sure how I've never come across a "Clean air separator". So the clean air side has a check valve that is supposed to only let air into the valve cover correct? Is that check valve in the valve cover itself or is it a device attached to the intake tube or the hose between the two? Out of all the GM trucks I've had none have come with stock air filters or tubes so maybe I've never noticed one.

Randy- Yes the can has both valve covers vented to it and a single line routed back to the intake as well as an air filter on top to allow atmosphere venting. It is the Mighty Mouse Draft can and supposed to help with the smell of the PCV through the filter on the catch can during normal driving. The theory is that the vacuum during normal driving is enough to pull the small amount of vapors being vented and stopping it from smelling bad. During WOT when a lot of crankcase pressure is being vented it allows whatever the engine cannot consume to vent to out the filter. My previous setup was both covers vented to a can that vented to the atmosphere and I could smell the vapors all the time.

So I misspoke earlier- the CSS replaces the hose that goes between the ps valve cover to Tb. The CSS itself is a check valve I believe, which releases as soon as throttle is lifted, and the small amount of oil that’s in it gets released into the valve cover so it never has to be drained. I don’t even know if it’s doing anything since there’s nothing to drain.

 

[Dantheman1540]

So I misspoke earlier- the CSS replaces the hose that goes between the ps valve cover to Tb. The CSS itself is a check valve I believe, which releases as soon as throttle is lifted, and the small amount of oil that’s in it gets released into the valve cover so it never has to be drained. I don’t even know if it’s doing anything since there’s nothing to drain.

Huh somehow I've never seen one I guess I'll have to look at the junkyard next time. The previous owner had the passenger valve cover connected directly to the intake tube so I did the same just because it was easy and I didn't feel like doing a catch can at the time. Main reason I got a catch can was to stop oil getting in the intake tube and the TB and since that was the only connection in front of the TB that could allow oil to enter I figured I'd start with putting the can there and later route the driver side to it aswell.

I do have a fairly significant oil consumption issue probably about a quart every 1,500 miles and the truck do not leak a drop so I thought maybe this would help that.

 

[randeez]

ok i got ya, that is the same catchcans i went with. I have their gen 5 pcv can on the driverside. valvecover>can>back of intake and the filter has a "float" in it under vac is pulls from the valvecover. underboost is pushes the float up releasing out the filter (checkball in the line to the intake)

i however added an open catch can to the passenger side, acts like the fresh air side to the crank under vac. under boost it will vent to atmosphere.

ive had very little so far in the passenger side can, driverside pulls a ton of oil/crap out. i turned my valvecovers around to put the bungs toward the front of the engine to hopefully cut some oil its trapping

the checkball is in the fitting that threads into the catchcan, may want to pull it apart and make sure it isnt gummed up in there

 

[Dantheman1540]

ok i got ya, that is the same catchcans i went with. I have their gen 5 pcv can on the driverside. valvecover>can>back of intake and the filter has a "float" in it under vac is pulls from the valvecover. underboost is pushes the float up releasing out the filter (checkball in the line to the intake)

i however added an open catch can to the passenger side, acts like the fresh air side to the crank under vac. under boost it will vent to atmosphere.

ive had very little so far in the passenger side can, driverside pulls a ton of oil/crap out. i turned my valvecovers around to put the bungs toward the front of the engine to hopefully cut some oil its trapping

the checkball is in the fitting that threads into the catchcan, may want to pull it apart and make sure it isnt gummed up in there

Glad we are on the same page, there is so much conflicting info about catch cans and crankcase venting its hard to figure out what's right, wrong or some troll hahaha. There was a good debate thread on pt.net about them a few weeks ago.

So you are still using the factory tubes on the valve covers you just spun the driver side around? I was going to do that but I wanted to convert to all AN fittings and had -10 fittings welded into the covers and the factory tube removed/welded over. Kind of a pain to be honest I have to connect the fitting to the valve cover before I tighten down the fuel rail.

 

[randeez]

nah, ive got aftermarket valvecovers with baffled -10 on them

what truck are you talking about? i missed how this all got started.

with both valvecovers going to the can and then to the intake its sealed at that point. whatever vac the intake hose is seeing is sucking on the crankcase all the time. whether the fresh air side is necessary or not i really dont know but i just wanted to have a 10an off each to its own can.

 

[Dantheman1540]

nah, ive got aftermarket valvecovers with baffled -10 on them

Was gonna say wow that's a lot of POWA through a little hole.

 

[randeez]

lol yea, talking with MM they said the setup im on now should be good for 1500hp

actually have an -8an to the back of the intake but the catchcan restricts it way down and they said dont worry about it

 

[Dantheman1540]

lol yea, talking with MM they said the setup im on now should be good for 1500hp

actually have an -8an to the back of the intake but the catchcan restricts it way down and they said dont worry about it

I think mine is -8 back as well its been a while since I've looked at it. I don't even want 1,000hp so I should be setup for good on that truck. This budget can was more of something to do than anything.

 

[BlackedOutHoe]

Another 3k, another oil change. Also swapped my silverado ECU out and the original Tahoe one back in after the almost bricked accident. Even put in a budget catch can finally and some cool incognito decals a buddy whipped up for me.

The catch can bracket is temporary to see if I like it there. If I do I'll clean it up and make it look good.
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this is the same place i put my CC, just have it facing the radiator vs firewall. Great minds, I tell ya.

 

[iamdub]

that's a lot of POWA through a little hole.

 

[randeez]

 

[Dantheman1540]

View attachment 256131 View attachment 256132 View attachment 256133 View attachment 256134

That is a beautiful setup! #catchcangoals

 

[Rocket Man]

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That damn snail is huge.

 

[iamdub]

That's interesting I didn't know there was a fresh air intake for the valve covers. Seems to me it ends up being a second source of oil in the intake as the hose was full of oil when I removed it.

That port on the PS valve cover should be sucking IN, not blowing out, so the oily air inside of it should not be able to flow out and into the intake duct. It's supposed to let the crankcase pull in filtered air from the intake duct. I'd imagine this to only really work at idle/closed throttle when vacuum is at a minimum. I've never investigated, but maybe there's a check valve in it (I don't see how it'd work without a check valve) and it's stuck open, letting intake vacuum suck oily air out of it and into your clean air intake tract?

I was planning to connect both sides to the can and eliminating the port on the top of the intake and having them both run back to the intake tube.

This wouldn't work. Well, it'd kinda work, but only cuz the PCV outlet (the port on the DS valve cover) and the vacuum in the intake tube would overpower the PS trying to draw air in. If anything, you should route it to the port on the manifold so it'd be behind the TB. If you route it going into the intake tube, ahead of the TB, that oily air would eventually gunk up the TB.

If one side is for fresh air then why do most people vent both valve covers to a single can then back to the intake?

I've never polled the masses, but I'd have to guess that if most people do this, it's because most don't know how the system is supposed to work. It'll still mostly work, but not as efficient as it could, as it was designed. The factory design works very well at evacuating the crankcase and reprocessing the gases without venting to atmosphere so you have to smell the oil- why screw with it? The problem is that the LS moves excess oil through the PCV system. You just need to filter this oil from the air as it flows in it's originally designed form, not try to completely change the flow characteristics.

My Silverado has dual -10an to a single can then -10 back to the intake but also has the ability to vent to the atmosphere under heavy boost.

Sounds like the same as outlined above- lesser efficient due to the PCV overpowering the fresh air inlet. With boost, all bets are off and everything changes. So, the "lesser efficient" tied-together valve covers only comes into play when not in boost.

The previous owner had the passenger valve cover connected directly to the intake tube so I did the same just because it was easy and I didn't feel like doing a catch can at the time.

This is how it is from the factory. So, the PO didn't change anything here or take any shortcuts.

Main reason I got a catch can was to stop oil getting in the intake tube and the TB and since that was the only connection in front of the TB that could allow oil to enter I figured I'd start with putting the can there and later route the driver side to it aswell

IMO, I'd stick to the factory design and just filter that one circuit- the dirty side that SHOULD have oil in it (although it's a lot/too much). If the other side is blowing oil into the intake, then I'm inclined to think there's a problem over there, like the stuck check valve theory previously mentioned. My system is stock but with a catch can on the dirty side. I run mine hard, so lots of engine load with WOT and high RPM. My intake tube is clean and dry and I consistently drain the same amount from my CC. I get no oily vapor smells after a hard run.

I do have a fairly significant oil consumption issue probably about a quart every 1,500 miles and the truck do not leak a drop so I thought maybe this would help that.

Either your engine is well-worn (or rings are just not sealing as well as they should) and/or you consistently drive like a bat outta hell and/or your PCV system has a problem. All of which are contributing factors to excess oil consumption.

 

[Dantheman1540]

That port on the PS valve cover should be sucking IN, not blowing out, so the oily air inside of it should not be able to flow out and into the intake duct. It's supposed to let the crankcase pull in filtered air from the intake duct. I'd imagine this to only really work at idle/closed throttle when vacuum is at a minimum. I've never investigated, but maybe there's a check valve in it (I don't see how it'd work without a check valve) and it's stuck open, letting intake vacuum suck oily air out of it and into your clean air intake tract?




This wouldn't work. Well, it'd kinda work, but only cuz the PCV outlet (the port on the DS valve cover) and the vacuum in the intake tube would overpower the PS trying to draw air in. If anything, you should route it to the port on the manifold so it'd be behind the TB. If you route it going into the intake tube, ahead of the TB, that oily air would eventually gunk up the TB.




I've never polled the masses, but I'd have to guess that if most people do this, it's because most don't know how the system is supposed to work. It'll still mostly work, but not as efficient as it could, as it was designed. The factory design works very well at evacuating the crankcase and reprocessing the gases without venting to atmosphere so you have to smell the oil- why screw with it? The problem is that the LS moves excess oil through the PCV system. You just need to filter this oil from the air as it flows in it's originally designed form, not try to completely change the flow characteristics.




Sounds like the same as outlined above- lesser efficient due to the PCV overpowering the fresh air inlet. With boost, all bets are off and everything changes. So, the "lesser efficient" tied-together valve covers only comes into play when not in boost.




This is how it is from the factory. So, the PO didn't change anything here or take any shortcuts.




IMO, I'd stick to the factory design and just filter that one circuit- the dirty side that SHOULD have oil in it (although it's a lot/too much). If the other side is blowing oil into the intake, then I'm inclined to think there's a problem over there, like the stuck check valve theory previously mentioned. My system is stock but with a catch can on the dirty side. I run mine hard, so lots of engine load with WOT and high RPM. My intake tube is clean and dry and I consistently drain the same amount from my CC. I get no oily vapor smells after a hard run.




Either your engine is well-worn (or rings are just not sealing as well as they should) and/or you consistently drive like a bat outta hell and/or your PCV system has a problem. All of which are contributing factors to excess oil consumption.

You sure get a cookie for the massive amount of replies.

The MM can in my silverado is setup exactly how they suggest for a boosted setup with a draft can and works fantastic so I'm not touching that.

Engine is likely well worn the PO said it was "Refreshed with the cam and heads upgrade" which likely means the bottom end is untouched. Really not concerned because it runs great and the oil/filter is squeaky clean. Might run a compression leak down test one day for fun. I'm leaning more towards PCV problems since there's oil in the intake and it's not leaking a drop. I have a driver side valve cover on my shelf and I looked at it today I see no check valve and there's certainly not one in the hose that was attached which could explain the oil issue.

I have yet to check the driver side PCV because I ran out of hose to attach it to the can but that will happen sometime soon.

I still don't see the point of the Clean air side when it could just suck oily air back in from the can when it's under vacuum not preasure and not have a chance of a check valve failing and causing oil back into the intake.

For now I will run the can on the passenger side only for a few weeks and record the following.

-amount of oil collected
-engine oil consumption/disappearance
-other notable irregularities


After those are determined I'll decide which way to hook it up next or if this can is total garbage just put it back to the way it was.

 

[Dantheman1540]

Also side project update. Crust caboose is officially usable. Besides a lack of registration but that's irrelevant. Still needs fenders and a few small patches in the deck then its paint time!