Instead of catch can, why not delete PCV?

VdellaV · December 2, 2019

30 minutes ago, SquireSCA said:

So I would have 3 lines total, right? The crankcase vent line, plus one each from the valve covers... The one going back to the manifold, the vacuum line, gets the cap.

Correct? I can use my current catch can, where I can simply take the "exit" line that was connected to the manifold vacuum line, and put one of those pod filters on that...

Yes, Correct.

I dont see the need of using the 3rd little line, you can just get rid of that and only use the other 2

Using it or not won't make a difference, but deleting it just simplifies the installation

SquireSCA · December 2, 2019

49 minutes ago, VdellaV said:

Yes, Correct.

I dont see the need of using the 3rd little line, you can just get rid of that and only use the other 2

Using it or not won't make a difference, but deleting it just simplifies the installation

What 3rd little line? You have one line from the crank case, the vent line... Then each valve cover has a vent line. Which one are you talking about?

VdellaV · December 3, 2019

4 hours ago, SquireSCA said:

What 3rd little line? You have one line from the crank case, the vent line... Then each valve cover has a vent line. Which one are you talking about?

Im talking about the 3/8 Crank Vent line that goes to the intake manifold. You can remove it and cap both ends and only run the breather lines from the valve covers to the catch can I posted above. Its so small that there is no point in keeping it and running it to the catch can.

green02crew · December 3, 2019

Im talking about the 3/8 Crank Vent line that goes to the intake manifold. You can remove it and cap both ends and only run the breather lines from the valve covers to the catch can I posted above. Its so small that there is no point in keeping it and running it to the catch can.

If there is any pressure in the crank, how will it be relieved?

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VdellaV · December 3, 2019

13 minutes ago, green02crew said:

If there is any pressure in the crank, how will it be relieved?

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It will blow off to the catch can and then to the atmosphere, instead of the intake box

SquireSCA · December 3, 2019

10 hours ago, VdellaV said:

It will blow off to the catch can and then to the atmosphere, instead of the intake box

How will it do that, if it is capped off, as you suggested? I feel like we are losing something here, in translation... LOL

VdellaV · December 3, 2019

3 hours ago, SquireSCA said:

How will it do that, if it is capped off, as you suggested? I feel like we are losing something here, in translation... LOL

There are 3 PCV Breathers on Gen V engines:

-One small 3/8" line that goes from under the throttle body to the manifold

-Two bigger 5/8" lines that go from the valve covers to the Air Box

Since the small line doesn't flow nearly as much as the other two lines, there is no point on keeping it around. You can Remove it and cap both ends.

All of the PCV vapors will now flow out of the valve covers, as normal. Instead of going into the Airbox, you route them to The Catch can and ventilate to the atmosphere.

SquireSCA · December 3, 2019

Hmmm... that little one under the throttle body is the one that pukes out the most oil... So you are saying just cap that one, and it won't build any pressure in there, because it's all connected internally to the valve cover areas and it can just vent from there?

Doug_Scott · December 3, 2019

9 minutes ago, VdellaV said:

There are 3 PCV Breathers on Gen V engines:

-One small 3/8" line that goes from under the throttle body to the manifold

-Two bigger 5/8" lines that go from the valve covers to the Air Box

Since the small line doesn't flow nearly as much as the other two lines, there is no point on keeping it around. You can Remove it and cap both ends.

All of the PCV vapors will now flow out of the valve covers, as normal. Instead of going into the Airbox, you route them to The Catch can and ventilate to the atmosphere.

If you vent to atmosphere you will notice a strong oil smell in the cabin.

I don't understand what you are trying to accomplish in venting to atmosphere. Why not just drill a large hole in the plate under the intake and bolt in a road draft tube?

Grumpy Bear · December 3, 2019

35 minutes ago, Doug_Scott said:

If you vent to atmosphere you will notice a strong oil smell in the cabin.

I don't understand what you are trying to accomplish in venting to atmosphere. Why not just drill a large hole in the plate under the intake and bolt in a road draft tube?

Two things we know about oil in the intake. It's plaques valves and it causes detonation. That is what is trying to accomplish. Saw it straight away.

The bigger question would be, "Why do you feel it is needed"?

IMHO? Glad you asked. Because people like to spread FEAR because FEAR sells things...like catch cans. The OEM has gone to great lengths to prevent the things he fears already. Not well at first, granted, but it has improved remarkably so. Well enough that under reasonable use and conditions one is not needed NOW. Yet...people, once fearful, have a hard time letting that fear go...don't you think? Think how much TEL substitute was sold when the US went unleaded. How many hardened valve seat jobs were sold and neither, as it turns out, were required. UNDER REASONABLE conditions.

SquireSCA · December 3, 2019

4 minutes ago, Grumpy Bear said:

Two things we know about oil in the intake. It's plaques valves and it causes detonation. That is what is trying to accomplish. Saw it straight away.

The bigger question would be, "Why do you feel it is needed"?

IMHO? Glad you asked. Because people like to spread FEAR because FEAR sells things...like catch cans. The OEM has gone to great lengths to prevent the things he fears already. Not well at first, granted, but it has improved remarkably so. Well enough that under reasonable use and conditions one is not needed NOW. Yet...people, once fearful, have a hard time letting that fear go...don't you think? Think how much TEL substitute was sold when the US went unleaded. How many hardened valve seat jobs were sold and neither, as it turns out, were required. UNDER REASONABLE conditions.

So you are saying that valve carbon buildup on modern gdi motors is a non issue? It’s FUD and nothing more?

Doug_Scott · December 3, 2019

56 minutes ago, Grumpy Bear said:

Two things we know about oil in the intake. It's plaques valves and it causes detonation. That is what is trying to accomplish. Saw it straight away.

The bigger question would be, "Why do you feel it is needed"?

IMHO? Glad you asked. Because people like to spread FEAR because FEAR sells things...like catch cans. The OEM has gone to great lengths to prevent the things he fears already. Not well at first, granted, but it has improved remarkably so. Well enough that under reasonable use and conditions one is not needed NOW. Yet...people, once fearful, have a hard time letting that fear go...don't you think? Think how much TEL substitute was sold when the US went unleaded. How many hardened valve seat jobs were sold and neither, as it turns out, were required. UNDER REASONABLE conditions.

I was referring to the venting to atmosphere part. I have been running a catch can for 10 years, and it will catch 6 or 7 ounces by the time it is due for oil change. Running a q-tip inside the manifold hose at the cannister comes out clean and dry. Probing the other line doesn't soak or show much more than dampness.

The oil hard clumps of crap on the intake valve stem won't cause detonation simply because it is not in the combustion chamber. A WOT run up to the highway speed limit will do wonders for any carbon deposits in the combustion chamber. PCV systems on Chevrolet small blocks with a carburetor would pull enough oil it would rot the inside of the PCV line where it attached to the front of carburetor at the base.

I started my apprenticeship in the early 70s, with the move to unleaded fuels started shortly after that. To this day I have never been asked to, and do not know of anyone being asked to install hardened seats. Even race engines that I saw being built did not bother with hardened seats.

Speaking of selling fear, in Canada we got air pumps (AIR system) on some engines, mostly manual transmission vehicles in the early 70s. Straight away many younger new car owners would cut the belt while car was under warranty, and then remove the entire system. The most common reason I heard was that the air pump took hp to run. Air pumps had the lowest drag on the engine of all the accessories. The water pump used more hp to drive compared to air pump. Every time manufacturers made a change, owners would do their damndest to disable it. The first thing sons would do to the family GM car was flip the air cleaner lid. Back then there was no internet. It was pretty impressive how fast the new mods spread. There was a lot of bullshit back then as well.

VdellaV · December 3, 2019

3 hours ago, SquireSCA said:

Hmmm... that little one under the throttle body is the one that pukes out the most oil... So you are saying just cap that one, and it won't build any pressure in there, because it's all connected internally to the valve cover areas and it can just vent from there?

Exactly !

The Valve Cover breathers and center breather are all like a Bottle with 3 openings

Cap one and the vapors will go out the other 2. Most of the PCV vapors go out the two valve cover breathers anyway

2 hours ago, Doug_Scott said:

If you vent to atmosphere you will notice a strong oil smell in the cabin.

I don't understand what you are trying to accomplish in venting to atmosphere. Why not just drill a large hole in the plate under the intake and bolt in a road draft tube?

Yes, but you can place the catch can anywhere you like, like under the bed or so.

2 hours ago, Grumpy Bear said:

Two things we know about oil in the intake. It's plaques valves and it causes detonation. That is what is trying to accomplish. Saw it straight away.

The bigger question would be, "Why do you feel it is needed"?

IMHO? Glad you asked. Because people like to spread FEAR because FEAR sells things...like catch cans. The OEM has gone to great lengths to prevent the things he fears already. Not well at first, granted, but it has improved remarkably so. Well enough that under reasonable use and conditions one is not needed NOW. Yet...people, once fearful, have a hard time letting that fear go...don't you think? Think how much TEL substitute was sold when the US went unleaded. How many hardened valve seat jobs were sold and neither, as it turns out, were required. UNDER REASONABLE conditions.

This is correct.

Catch cans are condensers. Once they get hot, they stop working and all the vapors fly past them. Its something popular people spend hundreds of dollars on, but if installed in recirculatory mode, do little to nothing to prevent carbon buildup

2 hours ago, SquireSCA said:

So you are saying that valve carbon buildup on modern gdi motors is a non issue? It’s FUD and nothing more?

Its a problem, but you can manage it. I have videos on how to remove carbon buildup every oil change, to keep the problem at bay:

15 minutes ago, Doug_Scott said:

I was referring to the venting to atmosphere part. I have been running a catch can for 10 years, and it will catch 6 or 7 ounces by the time it is due for oil change. Running a q-tip inside the manifold hose at the cannister comes out clean and dry. Probing the other line doesn't soak or show much more than dampness.

The oil hard clumps of crap on the intake valve stem won't cause detonation simply because it is not in the combustion chamber. A WOT run up to the highway speed limit will do wonders for any carbon deposits in the combustion chamber. PCV systems on Chevrolet small blocks with a carburetor would pull enough oil it would rot the inside of the PCV line where it attached to the front of carburetor at the base.

I started my apprenticeship in the early 70s, with the move to unleaded fuels started shortly after that. To this day I have never been asked to, and do not know of anyone being asked to install hardened seats. Even race engines that I saw being built did not bother with hardened seats.

Speaking of selling fear, in Canada we got air pumps (AIR system) on some engines, mostly manual transmission vehicles in the early 70s. Straight away many younger new car owners would cut the belt while car was under warranty, and then remove the entire system. The most common reason I heard was that the air pump took hp to run. Air pumps had the lowest drag on the engine of all the accessories. The water pump used more hp to drive compared to air pump. Every time manufacturers made a change, owners would do their damndest to disable it. The first thing sons would do to the family GM car was flip the air cleaner lid. Back then there was no internet. It was pretty impressive how fast the new mods spread. There was a lot of bullshit back then as well.

Again, Catch cans only function when they're cold. Thats where the little oil you're seeing comes from

Once the catch can heats up due to hot pcv vapors going through it, it won't condense them and let them into the intake anyway

SquireSCA · December 3, 2019

So if I cap the smaller bottom vent and vacuum line, and take the valve cover lines to a catch can that then vents to the air, I would stop all the oil from entering the intake manifold, yes?

At that point I can simple do a proper Seafoam cleaning(I have 20k miles on my 2018 truck) and from there I would get much more in the way of deposits because no more are entering the motor's intake?

VdellaV · December 3, 2019

4 minutes ago, SquireSCA said:

So if I cap the smaller bottom vent and vacuum line, and take the valve cover lines to a catch can that then vents to the air, I would stop all the oil from entering the intake manifold, yes?

At that point I can simple do a proper Seafoam cleaning(I have 20k miles on my 2018 truck) and from there I would get much more in the way of deposits because no more are entering the motor's intake?

Yes, and Yes.

Sorry if I was explaining it very clearly at the beginning, but now you got it