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Discussion Starter · #1 ·
This truck is my daily driver. I don't really want to take off the valve cover (and replace gasket and intake gasket in the process) just to see what I'm dealing with to figure out what kind of catch-can/vent setup I'm going to do.

Of all the talking that we do on these boards about the valve cover vents, has anyone actually taken a picture of the underside of the valve cover? Specifically on an '05 3.5L? Do these mysterious "baffles" that we keep hearing about acttually exist? Do both ports just open to the head, or is there some kind of routing between the two underneath the cover?

So how bout it, anyone have pics of the underside of the valve cover?
 

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Discussion Starter · #3 ·
Awesome, thank you. This looks metallic (mine is the polymer one in 2005), but I bet it's similar. How the heck can those baffles move enough to let a lot of oil through? I could see how a little might escape, but I was not expecting it to look like that.

Thanks for the photos!
 

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Awesome, thank you. This looks metallic (mine is the polymer one in 2005), but I bet it's similar. How the heck can those baffles move enough to let a lot of oil through? I could see how a little might escape, but I was not expecting it to look like that.

Thanks for the photos!
Same question. HOW does oil flow like a faucet through that. How does oil in engine defy gravity?
 

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Same question. HOW does oil flow like a faucet through that. How does oil in engine defy gravity?
Excessive blow-by can cause a steady stream of air to flow out of the breather. At that point, the oil is just along for the ride.
 

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Discussion Starter · #6 ·
I'm guessing under that metallic shield, it's an orifice? There's no check valve or anything, right?

I'm still really confused as to why both sides (which are connected inside the head) are needed. Can I plug one side, put a T-connector on the other, and run one hose to the intake before the TB, and one hose to the intake manifold?

I've heard so many conflicting things about this system. I'm thoroughly confused. I recently heard (here) that the intake tube picks up air inside the intake manifold (like a Pitot tube) and air flows from the intake manifold to the valve cover, then air can vent from the valve cover to the TB.

It's confusing. And also getting a thin film of oil in my intake, so I want to solve it. I need a way of figuring out air flow direction in an air line. Seems like a good science project.
 

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Excessive blow-by can cause a steady stream of air to flow out of the breather. At that point, the oil is just along for the ride.
Yea I know, you helped with my problems I was having haha. Sometimes the amount I was losing seemed unreal.

I'm guessing under that metallic shield, it's an orifice? There's no check valve or anything, right?

I'm still really confused as to why both sides (which are connected inside the head) are needed. Can I plug one side, put a T-connector on the other, and run one hose to the intake before the TB, and one hose to the intake manifold?

I've heard so many conflicting things about this system. I'm thoroughly confused. I recently heard (here) that the intake tube picks up air inside the intake manifold (like a Pitot tube) and air flows from the intake manifold to the valve cover, then air can vent from the valve cover to the TB.

It's confusing. And also getting a thin film of oil in my intake, so I want to solve it. I need a way of figuring out air flow direction in an air line. Seems like a good science project.
The direction of air flow is from passenger side (fresh air inlet) to driver side (dirty air). Some guys have vented it to atmosphere, which if you dont have excessive blow by is okay. If you have low compression on any cylinder causing blowby you will end up with the entire bottom side of of your pickup (and maybe even the side of your truck) coated in oil.
 

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Discussion Starter · #8 ·
Ok, thanks. That helps. Why do I have oil in my breather then? What conditions would cause crankcase pressure to be higher than intake pressure?

I'm thinking (now) that I'll add a catch can on the intake side, and put a check valve on the exhaust side, that only allows airflow from intake to valve cover.

If it needs to relieve pressure from that line (I can't see why unless the other side was clogged, though), maybe I can put another check valve that vented positive pressure to the air (through another can that wouldn't get oil everywhere), just in case it needs airflow in both directions on the exhaust side.
 

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Here is a pic of the orifice. The one on the exhaust side is the restricted one that replaces a PCV vale.

The exhaust side


The intake side
 

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Ok, thanks. That helps. Why do I have oil in my breather then? What conditions would cause crankcase pressure to be higher than intake pressure?

I'm thinking (now) that I'll add a catch can on the intake side, and put a check valve on the exhaust side, that only allows airflow from intake to valve cover.

If it needs to relieve pressure from that line (I can't see why unless the other side was clogged, though), maybe I can put another check valve that vented positive pressure to the air (through another can that wouldn't get oil everywhere), just in case it needs airflow in both directions on the exhaust side.
If you are getting excessive oil usage check compression.
 

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3.5 Crankcase Ventilation System description, from the 2005 Service Manual:

A crankcase ventilation system is used to consume crankcase vapors created during the combustion process instead of venting them to the atmosphere.

Fresh air is supplied through a filter to the crankcase, the crankcase mixes the fresh air with the blow-by gases and then passed through a positive crankcase ventilation (PCV) orificed tube into the intake manifold.

The PCV orificed tube restricts the flow rate of the blow-by gases using a 2.5 mm (0.098 in) orifice located in the camshaft cover tube. If abnormal operating conditions arise, the system is designed to allow excessive amounts of blow-by gases to back flow through the crankcase ventilation fresh air tube into the air cleaner resonator in order to be consumed by normal combustion.
 

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^ that is spot on. Thanks for sharing!

There's always a lot of confusion around breather/pcv systems. I feel like that post would make a good sticky on how the system actually works.
 

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Discussion Starter · #13 ·
Here is a pic of the orifice. The one on the exhaust side is the restricted one that replaces a PCV vale.

The exhaust side
(image removed)
The intake side
(image removed)
You say it's the exhaust side (connects resonator to valve cover exhaust side) that's restricted, but cart7881 says it's the intake side (connects valve cover intake side to intake manifold) that's restricted with an orifice.

3.5 Crankcase Ventilation System description, from the 2005 Service Manual:

A crankcase ventilation system is used to consume crankcase vapors created during the combustion process instead of venting them to the atmosphere.

Fresh air is supplied through a filter to the crankcase, the crankcase mixes the fresh air with the blow-by gases and then passed through a positive crankcase ventilation (PCV) orificed tube into the intake manifold.

The PCV orificed tube restricts the flow rate of the blow-by gases using a 2.5 mm (0.098 in) orifice located in the camshaft cover tube. If abnormal operating conditions arise, the system is designed to allow excessive amounts of blow-by gases to back flow through the crankcase ventilation fresh air tube into the air cleaner resonator in order to be consumed by normal combustion.
At least I think we have the direction correct, judging from everyone's posts (thanks!). I'm assuming the orifice side will be the most likely to become clogged and cause problems, so I'm curious to know which side is restricted. I'm using about a quart every 7000 miles, and I think most of it is deposited on the back of the motor, just by looking at it. That's not bad for a motor with 170k miles on it, I think.
 

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You say it's the exhaust side (connects resonator to valve cover exhaust side) that's restricted, but cart7881 says it's the intake side (connects valve cover intake side to intake manifold) that's restricted with an orifice.

At least I think we have the direction correct, judging from everyone's posts (thanks!). I'm assuming the orifice side will be the most likely to become clogged and cause problems, so I'm curious to know which side is restricted. I'm using about a quart every 7000 miles, and I think most of it is deposited on the back of the motor, just by looking at it. That's not bad for a motor with 170k miles on it, I think.
That just sounds like a rear main seal leak to me. I would replace seals and change my oil every 5k instead of 7k especially on high mileage trucks, but that's just my personal preference. catch can wouldn't hurt either, I have been wanting to do this.
 

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Discussion Starter · #15 ·
That just sounds like a rear main seal leak to me. I would replace seals and change my oil every 5k instead of 7k especially on high mileage trucks, but that's just my personal preference. catch can wouldn't hurt either, I have been wanting to do this.
It might be. I should say I meant the oil is on the top rear, on the valve cover (and I have a decent film in my resonator box). I cleaned the TB two years ago and it still looks pretty good, so it's not excessive. My plugs don't look great but I had the MAP sensor go bad about a year ago and I didn't diagnose it properly (I assumed it was the head issue, stupid to not investigate). It's possible it could be rear main seals. Not sure I want to know what's involved in replacing them.

I want to get the catch can mounted and get the intake oil figured out before I replace plugs.
 

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I went back out to my garage this morning and Cart7881 is correct the orifice is on the intake side. I was looking at the whole openings only but when I looked down into the opening I see the restriction. Sorry for the misinformation and confusion I may have caused. here is a pic of the orifice.
 

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Discussion Starter · #17 ·
I went back out to my garage this morning and Cart7881 is correct the orifice is on the intake side. I was looking at the whole openings only but when I looked down into the opening I see the restriction. Sorry for the misinformation and confusion I may have caused. here is a pic of the orifice.
Hey no apologies, you've helped a lot! Thanks!
 

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Legen..wait4it..Dary!
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It might be. I should say I meant the oil is on the top rear, on the valve cover (and I have a decent film in my resonator box). I cleaned the TB two years ago and it still looks pretty good, so it's not excessive. My plugs don't look great but I had the MAP sensor go bad about a year ago and I didn't diagnose it properly (I assumed it was the head issue, stupid to not investigate). It's possible it could be rear main seals. Not sure I want to know what's involved in replacing them.

I want to get the catch can mounted and get the intake oil figured out before I replace plugs.
Yeah its probably not a rear main seal then, Changing the seal is easy when the transmission is out lol. Word of advice, if you ever have any tranny work done, or a shop needs to pull it for any reason. Ask them to change the rear seal while its out! They will usually do it for the price of the seal (maybe$20 max) or for free. Its always a good idea to change it if you have that chance.

I would wait on changing plugs until the other stuff is taken care of as well. You say the leak is on the top rear, so maybe you can get away with just changing the valve cover gasket? you probably have already done that if you pulled the cover though.. best of luck I hate leaks.
 

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Discussion Starter · #19 ·
Yeah its probably not a rear main seal then, Changing the seal is easy when the transmission is out lol. Word of advice, if you ever have any tranny work done, or a shop needs to pull it for any reason. Ask them to change the rear seal while its out! They will usually do it for the price of the seal (maybe$20 max) or for free. Its always a good idea to change it if you have that chance.

I would wait on changing plugs until the other stuff is taken care of as well. You say the leak is on the top rear, so maybe you can get away with just changing the valve cover gasket? you probably have already done that if you pulled the cover though.. best of luck I hate leaks.
Haven't pulled the valve cover yet, thanks to having to remove the intake manifold. I'm glad I found rockauto's $10 manifold "gasket", because AC Delcos' is $30.

I just made another post asking if I could replace rocker arms (or whatever they're called on an OHC engine) and lifters without removing cams, while I'm in there.

My main goal is to look and see how the top part of the engine looks. That, plus an oil analysis, plus a leakdown test when I get my front-end alignment will give me an idea of how well the engine is doing. I'm almost ready to order one of those $20 2mm snake cameras on amazon, the ones with the LED's built in. I can inspect the cylinders then, through the spark plug hole.
 

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Legen..wait4it..Dary!
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aww man ive always wanted one of those! for uhh... research purposes..

as far as the rockers and lifters, without removing the cam...no clue.
 
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