Is AN -4 too small
Thread Starter
Staging Lane
Joined: Nov 2008
Posts: 82
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From: Mile High City
Is AN -4 too small So I drilled both of my fabricated valve covers and put AN -4 bulkhead fittings in. The fittings had npt threads so I epoxied a standard cap that I drilled a hole in to try and limit the amount of oil that it would be allowed to suck in.
Then ran AN -4 hose from each valve cover to a tee under the throttle body. Then out of that to the intake tube.
Now I've been having a crapload of problems with my valve covers sealing. I just thought it was my covers and how crappy the rubber seals were. So I finally gave up on those and got a set of Mr Gasket to glue in. Everything went well until I took it for an hour drive. I totally babied it, just cruised. But when I got to where I was going, it smelled like oil and on further inspection both the cover gaskets had pushed out. They separated in the middle.
Anyone else thinking the AN -4 is too small and I'm building up too much crankcase pressure and thats why I'm having these type of gasket troubles?
Thanks,
Jay
Then ran AN -4 hose from each valve cover to a tee under the throttle body. Then out of that to the intake tube.
Now I've been having a crapload of problems with my valve covers sealing. I just thought it was my covers and how crappy the rubber seals were. So I finally gave up on those and got a set of Mr Gasket to glue in. Everything went well until I took it for an hour drive. I totally babied it, just cruised. But when I got to where I was going, it smelled like oil and on further inspection both the cover gaskets had pushed out. They separated in the middle.
Anyone else thinking the AN -4 is too small and I'm building up too much crankcase pressure and thats why I'm having these type of gasket troubles?
Thanks,
Jay
Hard to believe it is crank case pressure. My only vent is the stock 3/8 inch line on the passenger's side. I do have a fairly low mile motor.
Try running with some type of breather on the fill cap for a while and see if that helps. My guess is the valve covers are coming unsealed from the heat cycle, especially since both covers are doing it I assume in the same place.
Are you getting much oil residue in the vent lines?
Try running with some type of breather on the fill cap for a while and see if that helps. My guess is the valve covers are coming unsealed from the heat cycle, especially since both covers are doing it I assume in the same place.
Are you getting much oil residue in the vent lines?
TECH Fanatic
Joined: May 2010
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From: Atlanta, Ga
Do you have any other sort of venting to atmosphere? Typically you need to have an in and an out just like the HVAC system in a house. The intake would be the line fitting in the air inlet and the out would be the pcv back to the engine side of the throttlebody.
What size hole did you drill in that cap and is it lined up with the AN opening?
Also I would run a larger hose from the T to the intake. Air can only move as fast as the smallest opening will allow. Think of it as adding the two 1/4 hoses together, you would ideally need a 1/2 hose for full eficiency. But I bet a 3/8 would do just fine.
Also I would run a larger hose from the T to the intake. Air can only move as fast as the smallest opening will allow. Think of it as adding the two 1/4 hoses together, you would ideally need a 1/2 hose for full eficiency. But I bet a 3/8 would do just fine.
Thread Starter
Staging Lane
Joined: Nov 2008
Posts: 82
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From: Mile High City
This is essentially a brand new motor; it only had 500 miles on it when I got it and I’ve only put about 300 on it since I got it started a couple weeks ago.
When I took the covers off, they were still held down REALLY well. So the gaskets should not have moved at all, let alone being pushed completely out like they were. The driverside pushed out on the bottom and the top of the long side, while the passengerside only pushed out on the top. So it was the driverside that was dumping oil on the header.
The hole I drilled in the caps is pretty small. I don’t remember off hand what size it was. It’s about the same size as the holes in the baffle that’s in the factory covers, but I guess there are about a half dozen in those. I could try and open that up to the same size as the fitting.
There doesn’t seem to be any oil residue in the lines. But I’m guessing that if I’m going to go thru and make all the lines bigger, than I should add an air/oil separator at the same time.
As for adding a breather, I thought we weren’t supposed to introduce 'unmetered' air into these motors.
Thanks,
Jay
When I took the covers off, they were still held down REALLY well. So the gaskets should not have moved at all, let alone being pushed completely out like they were. The driverside pushed out on the bottom and the top of the long side, while the passengerside only pushed out on the top. So it was the driverside that was dumping oil on the header.
The hole I drilled in the caps is pretty small. I don’t remember off hand what size it was. It’s about the same size as the holes in the baffle that’s in the factory covers, but I guess there are about a half dozen in those. I could try and open that up to the same size as the fitting.
There doesn’t seem to be any oil residue in the lines. But I’m guessing that if I’m going to go thru and make all the lines bigger, than I should add an air/oil separator at the same time.
As for adding a breather, I thought we weren’t supposed to introduce 'unmetered' air into these motors.
Thanks,
Jay
Maybe take a straight edge and make sure your fabricated covers are not warped. or maybe start your torque sequence in the center andmove out. sounds like maybe there isnt equal clamping force in the middle?
Either way I would still increase those holes to a larger size and swpa the T hose out.
Either way I would still increase those holes to a larger size and swpa the T hose out.
Thread Starter
Staging Lane
Joined: Nov 2008
Posts: 82
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From: Mile High City
Thanks,
Jay
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Or do you have that somewhere?
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Verdad Gallardo (If I read this right) Ha has a vent off each valve cover to a T splice then from that T to the intake tube. I Don't believe the T is tied into the throttle body, but just a means of joining the two vents to a single tube.
This is pretty similar to the OEM PCV where it uses a cross-over tube and then connects to the intake manifold.
This is pretty similar to the OEM PCV where it uses a cross-over tube and then connects to the intake manifold.
Thread Starter
Staging Lane
Joined: Nov 2008
Posts: 82
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From: Mile High City
You would be correct jmespe1.
Maybe I’m thinking of this system in reverse. But I thought the connection at the intake tube, which is before the throttle body but after the MAF sensor, created the vacuum on the two ports in the valve covers. So that any unburnt gases go back thru the motor’s combustion process again. Do I need a valve to stop any air from going back the other way?
I thought this was simple and that I understood it till I started spitting gaskets out and now it's got me second guessing everything.
Thanks,
Jay
Maybe I’m thinking of this system in reverse. But I thought the connection at the intake tube, which is before the throttle body but after the MAF sensor, created the vacuum on the two ports in the valve covers. So that any unburnt gases go back thru the motor’s combustion process again. Do I need a valve to stop any air from going back the other way?
I thought this was simple and that I understood it till I started spitting gaskets out and now it's got me second guessing everything.
Thanks,
Jay
You need a vacuum source. All you have connected is the fresh air source.
Thread Starter
Staging Lane
Joined: Nov 2008
Posts: 82
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From: Mile High City
Thanks for the diagram Pop n Wood. I see it says LS1 on it. I guess I didn’t mention it, but this is an LS3. So there is a vent on the front of the valley cover that is routed into the intake manifold behind the throttle body. Which I don’t believe the LS1’s had.
Edit
Sorry just went back and reread your earlier post and saw that I didn't see that you had already asked that.
I guess I need to get it started back up and see which way the air is moving in these AN -4 lines; if they are sucking or blowing. Because I guess I was thinking of this system backwards.
Thanks,
Jay
Edit
Sorry just went back and reread your earlier post and saw that I didn't see that you had already asked that.
I guess I need to get it started back up and see which way the air is moving in these AN -4 lines; if they are sucking or blowing. Because I guess I was thinking of this system backwards.
Thanks,
Jay
Last edited by Altitude 65; Oct 23, 2012 at 08:43 AM.
Here is a link to the LS3 set up (they are huge figures). That vent on the passenger side valve cover is only 3/8 inch. I would think your two 1/4 lines should provide more than enough air flow. Catch cans are always a good idea.
http://www.andersonperformance.net/L...e%20NA_PCV.jpg
http://www.andersonperformance.net/L...e%20NA_PCV.jpg
Thread Starter
Staging Lane
Joined: Nov 2008
Posts: 82
Likes: 0
From: Mile High City
Nice!
I am going to get and air/oil separator. But for now I’m going to pick up new gaskets on the way home. Drill out my restrictive caps on the fresh air side. Get it started up and pull the oil fill cap to see if there is vacuum there. It was one of the suggestions on that Anderson Performance site. If there’s vacuum there, I’m going to call the AN -4 lines good and then just add the separator on the dirty side. But if there’s not vacuum there, that is a whole new set of problems.
Thanks for all your help,
Jay
I am going to get and air/oil separator. But for now I’m going to pick up new gaskets on the way home. Drill out my restrictive caps on the fresh air side. Get it started up and pull the oil fill cap to see if there is vacuum there. It was one of the suggestions on that Anderson Performance site. If there’s vacuum there, I’m going to call the AN -4 lines good and then just add the separator on the dirty side. But if there’s not vacuum there, that is a whole new set of problems.
Thanks for all your help,
Jay
