PCV valve sucking oil GT40 intake

[Timmy390]

While tearing down my engine to fix the head gasket issue (see thread)
http://classicbroncos.com/forums/showthread.php?t=266011

I noticed I was sucking some oil into the intake via the PCV valve in the rear of my GT40 lower intake. My gt40 lower does have the baffle on the bottom. I do not have the small Crankcase Breather Element in the intake but have one on order. Could this be the issue?

Also, I'm running 2 PCV valves as the van valve covers I'm using had the PCV in it. I'm getting no oil from the PCV in the valve cover.

I have each PCV valve hooked up to a separate vacuum source on the upper intake. I'm pulling air into the engine via the other valve cover oil filler neck.

Is it possible I'm pulling too much vacuum?

Tim

 

[Viperwolf1]

You need to get rid of one PCV valve and find a way to let in fresh, metered air.

 

[Timmy390]

I'm pulling in fresh metered air from the intake hose between the MAF sensor and the throttle body. I've also tried pulling in unmetered air but that raises the idle due it being unmetered resulting in a vacuum leak.

So with 2 PCV's I'm pulling in too much fresh air thus sucking oil? I can cap the valve cover PCV easy enough.

Tim

 

[70_Steve]

I ran into the same issue with the GT40 manifold. There was a TSB about excessive oil consumption which included a new intake manifold baffle. The baffle is no longer available so I made my own. Didn't help...

As a test I installed one of my cheapie chrome stamped steel valve covers, with the PCV valve opening, on the drivers side and made a plug for the original PCV hole in the rear of the intake manifold. This all but eliminated my excessive oil consumption. I'm running stock Ford 5.0 cast valve covers, so I picked up another passenger side valve cover with the oil filler and modified the oil filler to take the stock PCV grommet. I've had no oil issues since.

 

[Timmy390]

Interesting.......my manifold has the larger baffle that was the "fix" per the pictures I've been able to find.

Guess the fix is to plug the one at the rear and use the other one in my valve cover.

I'll give it a try.

Tim

 

[Ourobos]

You should have a screen and grommet in the lower intake, with vacuum hose ran from PCV valve there up to the upper intake. Then you should have the fresh air you mentioned from valve cover nipple to throttle body. You should have NO valve cover breathers.. PCV is a simple closed system. If you have it the way the Ford engineers designed it, like I described, and you're still getting oil in there, I'd do a compression test and wonder about blow by at the rings.

 

[Timmy390]

My 96 explorer T-body does not have and perversion to hook up the PCV to it. The 96 explorer hooks to the air intake hose to draw metered air in and the vacuum source is the upper manifold. So I'm really stock but for adding an additional PCV attached to a separate vacuum source.

I've just ran a leak down test and do not have excessive blow by. Leak down was part of the head gasket troubleshooting.

Tim

 

[Ourobos]

How's the compression? Wet and dry? Leak down won't tell you how the rings are doing, just if you have a gasket leak or possibly a leaky valve.

 

[Timmy390]

Fresh build and I didn't do a compression test as I was hunting for a leak in the head gaskets into the water ports. Compression test would not have found my issue as the leak was very small. The above thread explains my HG issue and where it all went wrong during the build. hint, "just say no to the spray"

Once I get everything back together I can sure check compression.

Tim

 

[Ourobos]

Probably no need if it's a fresh build. What type of rings did you use, ductile iron, chromoly, etc? Was the block honed at a shop or with ball hone or what? Just trying to figure out how the oil is getting into the PCV, thinking out loud.

 

[Timmy390]

Block was punched 0.020 over, used Mahle Plasma-Moly Ductile Iron rings. All the block work was done at a machine shop. I assembled the engine per HTB SBF. Looking back at my build notes the gaps on the compression rings were 0.016 to 0.017.

I only see oil in the one PCV in the rear of the GT-40 intake. The other one in the valve cover is clean.

Tim

 

[chuzie]

I'd like to see pics of y'alls valve covers. I'm running ford motorsports covers without a filler. Had to modify a 1/4 turn breather to act as a pcv source. Not thrilled about it. Still have pcv valve in rear and she sucks a quart every 6 hours on the highway.

I want to fix this.



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[Ourobos]

If you're carbureted it's a simple solution.. Ditch the PCV and vent each valve cover.. That's what I did on my 408w.

Otherwise with EFI, I'd say it's a MUST to have the filter in the lower intake's PCV boss, then the grommet and PCV valve firmly on top of that.. Then the vacuum source to the upper intake PULLS the crank case pressure into the manifold. Of course you have to have a fresh air source in order to pull out, thus any metered air into the engine works.. Again, no vented covers ETC with an EFI PCV setup, or you'll be pulling unmetered air.. Do it just like Ford designed..

Chuzie, what does your system consist of exactly.. That's crazy oil usage.

 

[chuzie]

351w gt40 upper/lower

Explorer efi

Pcv valve on rear to intake (mesh installed)

Valve cover to metered air

I don't have any smoke or soot or leaks

She needed 2 quarts by the time i got to Townsend from tampa.

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[Ourobos]

Is there a baffle in the cover below the PCV valve? How fresh is YOUR engine?

 

[Timmy390]

I'm using stock ford parts. One 96 E350 van P-side cover with PCV grommet and one 90's F150 cover with oil filler neck and cap. Van P-side cover on the D-side and the F150 cover is on the P-side. Had to do this for clearance issues.

Both valve covers have baffles......

 

[chuzie]

I remember it having a flat plat on the bottom when i installed it. Is that what you ate referring to? If not, can i identify it by looking down into the pcv hole?

Tim, freaking awesome. I am going to junkyard tomorrow and grabbing those! Was the van cover easy to snag or a nightmare? I know they can be hit or miss.

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[Ourobos]

Yes Chuzie, that plate is the baffle.. If you pop the oil cap and see your rocker arms, you DON'T have a baffle.. I'll bet you'd see a steel plate. I'm wondering if you don't have other issue for you consumption..

 

[Ourobos]

Timmy390, I'd plug that other hole in the second valve cover..

 

[Timmy390]

The van cover is a pain because it's a van. I was using the 96 van as my donor for the 351W swap so after pulling the engine it was easy......

Tim