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You need a PCV valve on one valve cover and a VENT on the other valve cover to allow your PCV to work correctly..
I am guessing your PCV is drawing a vacuum with NO source of air INTO the engine... I have seen this before..
Mostly correct. As written, that’s the typical arrangement for a mod motor. Locations don’t have to be on valve covers. A typical pushrod engine will have the PCV valve in the back of the intake manifold where it draws from the valley under the intake and the fresh air line to a valve cover (oil fill neck).

To generalize, a correct PCV system will have a PCV valve placed with access into the crankcase and have a hose running from it to a vacuum source. The fresh air tube will connect between a different crankcase location and a metered air source pre throttlebody (assuming MAF) that won’t see pressure if forced induction.
 

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Discussion Starter · #22 ·
I noticed that the engine sat for years. Could it have gotten cold, froze and cracked a head from having water in it?

ks
It did sit for some years…in and out of the car. I really feel like i am doing the gaskets well and heads only have 1200ish miles so i would think the cracked head could be a real possibility. It passed a leak down and compression test but it still could have a crack i guess? Is there a way to test or they would have to come off and go to a machine shop? I also appreciate all your input by the way!
 

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It did sit for some years…in and out of the car. I really feel like i am doing the gaskets well and heads only have 1200ish miles so i would think the cracked head could be a real possibility. It passed a leak down and compression test but it still could have a crack i guess? Is there a way to test or they would have to come off and go to a machine shop? I also appreciate all your input by the way!
A leak down/compression test would only test the integrity of the "seal" between the top of the rings to the valves it wouldn't catch a cracked head near a valve guide or ??...just tossing out ideas..

Once you retest the amount of vacuum within the block when all vacuum lines are off then we can think how to check ideas...take a video when you test the vacuum.
Pressurizing the block from the dipstick is a great idea, just need to make sure all other holes are completely plugged to hear where the leak may be coming from.

ks
 

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Discussion Starter · #24 ·
A leak down/compression test would only test the integrity of the "seal" between the top of the rings to the valves it wouldn't catch a cracked head near a valve guide or ??...just tossing out ideas..

Once you retest the amount of vacuum within the block when all vacuum lines are off then we can think how to check ideas...take a video when you test the vacuum.
Pressurizing the block from the dipstick is a great idea, just need to make sure all other holes are completely plugged to hear where the leak may be coming from.

ks
Ok great! I will work on capping everything off and do a video of it running.
 

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There is a thread floating around this sight about doing a smoke test to find leaks. I think it was more for testing turbocharger piping but this would also be a great way to find any vacuum leaks around the intake ports once you get that far.

ks
 

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Flow of the PCV system-
The PCV cycles Fresh metered air through the crankcase and into the intake, pulling blowby with it.

that fresh air enters at the passenger valve cover. You have removed that source of fresh air and instead supplied a vacuum source there, so that no air ever enters the crankcase.

that is your only problem.
not the gaskets, not the valves, rings, heads, intake or bottom end.
it is the missing supply of fresh metered air.

Metered air ENTERS the crankcase at the passenger valve cover, is then pulled throughout the crankcase, up through the PCV valve and back into the upper intake plenum (the vacuum source).

Do Not connect the valve cover inlet to the intake, that eliminates any source of metered air from entering the crankcase, instead it applies VACUUM to the crankcase in 2 spots, the PCV valve & the valve cover.

Everything behind the throttle body is VACUUM.
You have to connect the valve cover inlet to something before the throttle body AND after the MAF.
 
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Flow of the PCV system-
The PCV cycles Fresh metered air through the crankcase and into the intake, pulling blowby with it.

that fresh air enters at the passenger valve cover. You have removed that source of fresh air and instead supplied a vacuum source there, so that no air ever enters the crankcase.

that is your only problem.
not the gaskets, not the valves, rings, heads, intake or bottom end.
it is the missing supply of fresh metered air.

Metered air ENTERS the crankcase at the passenger valve cover, is then pulled throughout the crankcase, up through the PCV valve and back into the upper intake plenum (the vacuum source).

Do Not connect the valve cover inlet to the intake, that eliminates any source of metered air from entering the crankcase, instead it applies VACUUM to the crankcase in 2 spots, the PCV valve & the valve cover.

Everything behind the throttle body is VACUUM.
You have to connect the valve cover inlet to something before the throttle body AND after the MAF.
From what I can tell he has vacuum in the crankcase with EVERYTHING DISCONNECTED to the crankcase.

I can unhook the pcv and all vacuum lines and have it immediately. It builds as it’s running and then starts with the humming noise as it pulls through the lower intake gaskets. Have redone these things 8 times and once i put a different upper and lower to make sure its not the intake.
His posts are a bit confusing causing people to go off on tangents so hopefully if he does my testing we will find out more.

ks
 

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Discussion Starter · #28 ·
Flow of the PCV system-
The PCV cycles Fresh metered air through the crankcase and into the intake, pulling blowby with it.

that fresh air enters at the passenger valve cover. You have removed that source of fresh air and instead supplied a vacuum source there, so that no air ever enters the crankcase.

that is your only problem.
not the gaskets, not the valves, rings, heads, intake or bottom end.
it is the missing supply of fresh metered air.

Metered air ENTERS the crankcase at the passenger valve cover, is then pulled throughout the crankcase, up through the PCV valve and back into the upper intake plenum (the vacuum source).

Do Not connect the valve cover inlet to the intake, that eliminates any source of metered air from entering the crankcase, instead it applies VACUUM to the crankcase in 2 spots, the PCV valve & the valve cover.

Everything behind the throttle body is VACUUM.
You have to connect the valve cover inlet to something before the throttle body AND after the MAF.
Originally i didnt have anything hooked to the oil fill tube amd had this problem. I will unhook it and put it before my throttle body. I am going to unhook all the vacuum and start over. I hope i am not overthinking this but would love for that to be my only problem though for sure
 

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Originally i didnt have anything hooked to the oil fill tube amd had this problem. I will unhook it and put it before my throttle body. I am going to unhook all the vacuum and start over. I hope i am not overthinking this but would love for that to be my only problem though for sure
As you may be able to tell there is confusion on EXACTLY what is hooked up and how it is hooked up.
This is why I want EVERYTHING from the crankcase completely disconnected from the intake to verify that there is NO vacuum inside the crankcase....there shouldn't be.

1. If there is still vacuum then something serious is going on; Gaskets, cracked head, etc..I doubt it tho b/c "most" of the time the motor will blow oil, burn water, run like crap, etc...

2. If there is no vacuum then it's a matter of getting the lines hooked back up correctly and get you back on the road.

ks
 

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Discussion Starter · #30 ·
As you may be able to tell there is confusion on EXACTLY what is hooked up and how it is hooked up.
This is why I want EVERYTHING from the crankcase completely disconnected from the intake to verify that there is NO vacuum inside the crankcase....there shouldn't be.

1. If there is still vacuum then something serious is going on; Gaskets, cracked head, etc..I doubt it tho b/c "most" of the time the motor will blow oil, burn water, run like crap, etc...

2. If there is no vacuum then it's a matter of getting the lines hooked back up correctly and get you back on the road.

ks
Yes thank you!! The more i read the more nervous i get. I have family stuff tonight and tomorrow but will be on it and able to move to get all unhooked. Thanks again!!
 

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My Mechanic friend was having problems with a brand new rebuilt bbc that sounded like the engine bearings had NO lube to them... The screech was terrible...
He had nothing to do with the rebuild or install, it was just laid on his lap to fix the "screeching" noise.... This guy is one of the most competent mechanics I know and he could not figure it out....
Mechanic was just about to drop the oil pan to check the bearings when I showed up... No, I am not a master mechanic at all, but I had just read an article on PCV flow in an engine... I should say I am talking about carbureted engine here...
Car owner had a PCV in one valve cover and an airtight rubber plug in the other one that sealed it tight... I reached down and tried to pull out the rubber " oil fill " plug but it was being sucked so tight from vacuum I could not... Turned off engine, pulled the rubber plug, wallah it was fixed.... Installed a vented oil fill cap where the rubber plug was....
The screeching was the engine sucking at any spot where it could get air as the PCV valve was creating a vacuum within the entire engine..... When you say you have sucked in gaskets it reminds of this same engine as it would have surely sucked in gaskets eventually......
 

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Discussion Starter · #32 ·
As you may be able to tell there is confusion on EXACTLY what is hooked up and how it is hooked up.
This is why I want EVERYTHING from the crankcase completely disconnected from the intake to verify that there is NO vacuum inside the crankcase....there shouldn't be.

1. If there is still vacuum then something serious is going on; Gaskets, cracked head, etc..I doubt it tho b/c "most" of the time the motor will blow oil, burn water, run like crap, etc...

2. If there is no vacuum then it's a matter of getting the lines hooked back up correctly and get you back on the road.

ks
As you may be able to tell there is confusion on EXACTLY what is hooked up and how it is hooked up.
This is why I want EVERYTHING from the crankcase completely disconnected from the intake to verify that there is NO vacuum inside the crankcase....there shouldn't be.

1. If there is still vacuum then something serious is going on; Gaskets, cracked head, etc..I doubt it tho b/c "most" of the time the motor will blow oil, burn water, run like crap, etc...

2. If there is no vacuum then it's a matter of getting the lines hooked back up correctly and get you back on the road.

ks
alright…so i have all vacuum lines unhooked from intake and all rhe ports capped off. Side not is that all the times i have done these intake gaskets i have been using my holley systemax set up and since i thought the lower intake was my problem i bought this polished gt40 and put it on the last time and had the same problem. Going to do a video now with a vacuum gauge hooked to my oil fill tube
 

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Discussion Starter · #33 ·
alright…so i have all vacuum lines unhooked from intake and all rhe ports capped off. Side not is that all the times i have done these intake gaskets i have been using my holley systemax set up and since i thought the lower intake was my problem i bought this polished gt40 and put it on the last time and had the same problem. Going to do a video now with a vacuum gauge hooked to my oil fill tube
This is not letting me post a video on here…just pics?
 

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This is not letting me post a video on here…just pics?
You may need a Youtube account or ?? to host the vid then you can link it here.
Pics will also work if needed. The pics are just so us viewers are assured that all the v-lines to the crankcase are removed..

If you vacuum tested the crankcase what did the vacuum read?

ks
 

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Discussion Starter · #35 ·
You may need a Youtube account or ?? to host the vid then you can link it here.
Pics will also work if needed. The pics are just so us viewers are assured that all the v-lines to the crankcase are removed..

If you vacuum tested the crankcase what did the vacuum read?

ks
You may need a Youtube account or ?? to host the vid then you can link it here.
Pics will also work if needed. The pics are just so us viewers are assured that all the v-lines to the crankcase are removed..

If you vacuum tested the crankcase what did the vacuum read?

ks
You may need a Youtube account or ?? to host the vid then you can link it here.
Pics will also work if needed. The pics are just so us viewers are assured that all the v-lines to the crankcase are removed..

If you vacuum tested the crankcase what did the vacuum read?

ks
You may need a Youtube account or ?? to host the vid then you can link it here.
Pics will also work if needed. The pics are just so us viewers are assured that all the v-lines to the crankcase are removed..

If you vacuum tested the crankcase what did the vacuum read?

ks
Alright…here are some pics. You can kinda see that all is plugged off and unhooked. I fired it up and it has no vacuum now!?!
Watch Analog watch Gauge Clock Measuring instrument
 

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PERFECT! That's what I expected so the intake is sealed with no issues.

The "excessive" vacuum that you were experiencing was due to a vacuum line pulling a vacuum on the crankcase. From here it's a matter of getting the lines connected CORRECTLY to where they are supposed to go.

Question: At this time we will need to know what modifications to the intake and throttle body there are in order to know if the vacuum lines can be installed EXACTLY like a factory car has them or what aftermarket parts are on it so the lines can be connected correctly.

What I suspect, and what others have posted, is the PCV hose, the PCV itself, and a "fresh air vent" are not correct. So a pic of the PCV hose, PCV valve and the "fresh air" vent will help us see how the PCV system is set up.

ks
 

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Discussion Starter · #37 ·
PERFECT! That's what I expected so the intake is sealed with no issues.

The "excessive" vacuum that you were experiencing was due to a vacuum line pulling a vacuum on the crankcase. From here it's a matter of getting the lines connected CORRECTLY to where they are supposed to go.

Question: At this time we will need to know what modifications to the intake and throttle body there are in order to know if the vacuum lines can be installed EXACTLY like a factory car has them or what aftermarket parts are on it so the lines can be connected correctly.

ks
This is crazy!! I can’t believe i have been doing this to myself!? I am a body/paint guy by the way lol. I should probably go back to the systemax intake that i had on here in the first place. But i have only the fuel regulator, brake booster, charcoal canister actuator, line that goes to dash, pcv, and oil fill that have vac lines. I do have the factory vac tree i use on the driver side apron too.
 

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So where are you routing the hose from your Trick Flow fill tube on the valve cover?

What is your Vacuum gauge connected to? If you are connected to the crankcase and have no vacuum now, your issue is not within the intake gaskets.


As stated, the PCV system requires a LOOP with vacuum only being pulled from one side (at the PCV valve on the back of lower intake on an EFI 5.0).

Carb'ed vehicles with PCV systems simply had a breather on one valve cover (or a hose from the valve cover to the lower air filter housing), and a PCV valve on the other valve cover, with a hose from the PCV valve to the carb or intake vacuum source.

The 5.0 PCV system runs a hose from the PCV valve on the back of the lower intake to a vacuum connection on the upper intake. The inlet side is typically connected from the oil fill tube on the passenger side valve cover to a connection on the throttle body itself, or the intake tube prior to the the throttle body.

Either way, one side of the LOOP pulls vacuum, and the other side is just filtered air.


FYI, in the case of excessive vacuum in the loop pulling crankcase oil into the intake tract, oil/air separators can be installed in-line.
 

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This is crazy!! I can’t believe i have been doing this to myself!? I am a body/paint guy by the way lol. I should probably go back to the systemax intake that i had on here in the first place. But i have only the fuel regulator, brake booster, charcoal canister actuator, line that goes to dash, pcv, and oil fill that have vac lines. I do have the factory vac tree i use on the driver side apron too.
I would separate the reassembly of the v-lines into two areas:
1. PCV lines ONLY. I would leave all the other lines disconnected but only route/attach the lines for the PCV system, then test it. Take pics of these lines, fresh air vent hole and the PCV valve used so we can verify that the routing and valve are correct. Test it to see how much vacuum is pulled like you just did.
If the above test passes then the PCV is good to go.

2. Reattach the rest of the v-lines.

I have no idea how the PCV lines are supposed to run on your car so I would find a pic somewhere and make sure I follow that diagram. It should be very simple and maybe someone on here can post a pic of the FACTORY routing on a factory motor for comparison.

ks
 
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