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PCV Valve Passing Massive Amounts of Oil into Intake

Past_Miner

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I have been having some vacuum problems on my 351W with EFI so I pulled my upper manifold and replaced gaskets, checked connections, etc. As a part of the vacuum line clean-up I installed the PCV valve in the lower manifold where it belongs, routed the passenger side valve cover vent to the throttle body and put a sealed oil fill cap in the drivers side valve cover.

I started it back up after reassembly and only made it a few minutes before I started getting blue smoke. I pulled the upper back off and it was full of oil. I don't mean it had residue, I mean it was pouring out of it when I lifted it off of the lower.

I searched the forum and found a few similar issues but I never saw any responses that the suggestions fixed the problem. Should I go back to the PCV in the valve cover with a vented cap on the other side? I have always read that this was incorrect for EFI but I never had any problems like this with that arrangement. I also read in one post that using a Motorcraft PCV valve instead of a cheapo Fram unit will stop this. I have the GT-40 lower with the Explorer upper.

Anybody have any suggestions?
 

bronko69er

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The most recent thread was involving an edelbrock lower where the oil baffle was not installed..... I'll see if I can find it.
 

chuck

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You need something to block the oil from splashing into the bottom of the PCV valve. If you don't have the metal shield inside you can use a rubber grommet for the pcv valve that has a bottom with a slit in it.
 
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You need something to block the oil from splashing into the bottom of the PCV valve. If you don't have the metal shield inside you can use a rubber grommet for the pcv valve that has a bottom with a slit in it.

I can't remember if the shield was missing from the lower when I received it or not. The upper is still off today so I will pull the grommet out and look down in there tonight when I get home. The grommet I have now has a metal screen in the bottom of it. Is there a different one that has a rubber bottom available or can I just cut a piece of gasket material with a slit in it and stuff it in the bottom of the grommet I have?
 

justinoshea

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.. I pulled the upper back off and it was full of oil. I don't mean it had residue, I mean it was pouring out of it when I lifted it off of the lower.

I had/have a similar issue with the TFS street intake. baffle installed but still sucks oil. TFS instructions said to epoxy the oil galley plug so that no oil could pool in it under that area. no change. better now that the rings seated but still not quite right. good luck.
 

bronco italiano

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I have a pcv from pass. valve cover to efi intake pcv to upper manifold to driver side valve cover with pcv. Have I overdone it, or just really screwed it up? Now I do not know where to put the throttle body tube to? Any ideas? Yes I bought the rear manifold screen/grommet/pcv from Ford too. Thanks, BI
 
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I have a pcv from pass. valve cover to efi intake pcv to upper manifold to driver side valve cover with pcv. Have I overdone it, or just really screwed it up? Now I do not know where to put the throttle body tube to? Any ideas? Yes I bought the rear manifold screen/grommet/pcv from Ford too. Thanks, BI

I read about a few people doing this on a couple of the Mustang forums. The theory was that the velocity through the PCV valves would be reduced so the tenedncy to pick up oil would be reduced. I never saw much in the way of comments about success. I have thought about doing exactly what you describe so let me know how your works.

BTW, I checked and I do have the baffle and screen under my manifold PCV valve. There is one under the valve cover vent grommet too. So much for wishing for an easy fix.
 

gddyap

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I have this same problem with my 351 GT40 upper and lower. I had read that long-time Bronco guru Coby Hughey had the same problem on his 427 stroker and Ford Racing had told him there were two different baffles on the GT40, a small and big. They had no other suggestions other than making sure the filter was clean. He figured out a way to use carburetor valve covers on his EFI so the PCV was moved to the valve covers. My solution that I think mostly works was to put a small round plate under the PCV filter with a hole drilled in it like an orifice. It reduces the amount of suction through the PCV. It reduces the oil being sucked up but it also reduces the amount of bad gases being sucked up as well. If I ever get around to redoing the engine, I'll look at switching to carb valve covers.
 

justinoshea

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One thing I did to understand my problem was to temporarily install a piece of clear hose to see how much oil is getting sucked up, and how fast (velocity). I also experimented with a piece of crimped steel tubing to alter the flow in the tube. I also tried catch can, filters, separators and such but didn't find anything worth using. there are oil/air seperators out there but they are very exspensive for a good one.
 

COBlu77

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I had the same issue at first and was told by a friend that owns a shop that all PCV valves are not created equally. He suggested getting a Motorcraft PCV for a 86-93 Mustang along with a new screen and grommet. It worked. I was using an Autozone PCV prior. A little oil is normal.

If you restrict your PCV it will casue blow by to the path of least resistance. The whole PCV system can't be open to the atmosphere (ie, a breather cap etc) or you will have a vacuum leak that will mess with the EFI and cause you to run lean, pop, etc.
 

DirtDonk

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I have a pcv from pass. valve cover to efi intake pcv to upper manifold to driver side valve cover with pcv. Have I overdone it, or just really screwed it up? Now I do not know where to put the throttle body tube to? Any ideas? Yes I bought the rear manifold screen/grommet/pcv from Ford too. Thanks, BI

Clear this up for me BI. You're running just a tube/hose from the pass. side valve cover to the intake tract near the throttle body, correct? Is it on the air-filter side of the TB or the engine side?

And you're running a tube from the intake upper manifold/plenum to an actual PCV Valve in the driver's side cover?

What do you have in the stock location at the rear of the lower manifold? You said you bought the screen/grommet/pcv from Ford. Does that mean that you have a PCV valve in the stock location too? Or just a tube? Either way, where is the other end of that one connected?

If you have a second PCV valve, then yes, it's plumbed wrong. Doubt it would actually hurt anything in the short term, but it's not right. Should only be ONE actual valve, and ONE return line that would be attached near the Throttle Body.
Seems to me that it should be ahead of the TB, but I've heard others say that it's just behind the TB so that it's part of the measured air into the engine. That sounds fishy to me though, since anything behind the TB is in a vaccum and that would mess with the whole system's function.
I would think that your tube would attach to the plastic air inlet tubing between the TB and the air filter, so that it can pull clean air through it and not be fighting a vacuum.
But who am I to argue with others that have actually done the EFI swap. I'm not there yet myself, but it still sounds fishy to me. All the PCV does is to use engine vacuum (at one end) to suck bad gasses out of the crankcase through the PCV Valve and to pull clean air into the crankcase from the filtered air stream.
And all the valve itself does is to control the amount and timing of that suckage. Kind of a controlled vacuum leak if you will.

So I'm curious how yours is hooked up exactly.

Thanks

Paul
 
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I think DirtDonk has it right. Theoretically, the PCV valve should be in the rear of the lower manifold and the valve covers should be of sealed design. There should be an open (meaning no check valve) supply line to one or both of the valve covers so that the PCV valve doesn't just end up putting the whole block under vacuum. For EFI those open lines need to pull air from a metered source. Anyplace after the Mass Air Meter would be a source for metered air. Anyplace after the TB itself would be under the same, or nearly the same vacuum as the PCV valve so it would not create any real flow. I'm using an Explorer TB that has a connection for the valve cover vent between the butterfly and the MAF.

This is exactly how I had mine plumbed the other day when it started sucking oil. Previous to that it was basically a carb setup under full vacuum. I switched to a Motorcraft PCV last night and it doesn't seem to be blowing blue smoke anymore. I now have the PCV in the lower manifold, a sealed fill cap in the drivers side valve cover and another PCV valve in the passenger side that is hooked to the TB. After about an hour of really romping on it last night I noticed that the engine was searching for a good idle point when I would stop at a light. I remember this used to happen with my old carbeurated Mustang when the PCV valve got stuck closed. I would bet that I can solve that problem by putting an open elbow in the place of the PCV valve in the valve cover. Early in the run it ran smoother than it ever has, which I am now assuming was because it hadn't had time to build up pressure yet.

My only concern is that open elbow will create enough volumetric flow to start carrying oil into the intake again. However, the comment about all PCV's not being created equal is probably true. The Motorcraft one looks and operates completely different than the cheap AZ valves I have.

I got my wisdom teeth pulled yesterday, all four at 39 years old. I'm just sitting around feeling sorry for myself anyway so I will make this change and let everyone know if it starts working correctly.

BTW, thanks to everyone for the comments and the help.
 

DirtDonk

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Bummer on the teeth buddy. I only had one side done at a time so that I could still eat while recovering.
The doc argued with me that if I didn't do them all at once I'd never come back for the second batch. Hell no. I'd rather eat!
If I really needed them out (I did) I'd be back for the second round (I was).

Still not fun though. Hope you like soup and fruit-smoothies!
Now, what were we talking about again? Oh yeah, Broncos.
Yeah, if there were supposed to be two PCV valves in the system, Ford would have put two in. But they only work in one direction and are supposed to have vacuum pulling them. The "pill" inside is different for different engines too, so they open and close at differring vacuum signals based on the characteristics of that engine.
Putting two in just pits one against the other and defeats the purpose.
So you shouldn't have too much flow with just a tube on one side since they work fine that way stock. So if it's sucking oil through it then there's another issue at work.
Seems to be a common problem though, so it will be interesting to track them all down and give a cure that we can all refer to when it crops up in someone's new EFI conversion.
Good luck with both. The PCV and the teeth, that is.

Paul
 
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I put the elbow back into the valve cover and connected it to the TB. Then I managed to find a good, sealed oil fill cap that fit my valve covers. The Motorcraft PCV valve seems to be working and it quit sucking oil. It seems to me that the solution is a combination of the correct (in this case meaning Motorcraft) PCV valve and getting the vent connected right. It is definately running better now.

Now...to get back to some soup
 

kirkallen143

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You need something to block the oil from splashing into the bottom of the PCV valve. If you don't have the metal shield inside you can use a rubber grommet for the pcv valve that has a bottom with a slit in it.

X2. This is an easy one fellers, baffled rubber grommet.
 
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X2. This is an easy one fellers, baffled rubber grommet.

It's only easy if you can find a baffled one that fits into the manifold opening. The ones for the valve covers are on the shelf in every parts house. They have too small an OD to fit into the manifold so they won't seal. I have not been able to find one for the manifold anywhere. If you have a link to one I can buy please share it.
 
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