I did a complete manifold swap on a 2000 today and had a chance to take a close look at the crankcase venting on the gen II Lightnings. Since every manifold I've taken off and every intercooler I've looked at was an oily, ugly mess, I think it is time to take a look at how the system actually works, rather than just patching it by using different PCV valves or putting an industrial grade air compressor filter in the line. The early PCV systems were pretty simple. They had a tube running from inside the air cleaner to a valve cover. That tube provided filtered air which was to flow into the engine. The other valve cover would then have a PCV valve which hose attached to it that ran to a vacuum port and hence into the intake system. The theory was that under low load, fresh air flows in, picks up the oil vapor and is then sucked into the combustion chambers and burned. Under heavy load, if the blowby of the negine was greater than what the PCV valve couod handle, the excess flow went backward up the fresh air pipe and into the air cleaner, where it was sucked into the engine and burned. As long as the engine was in decent shape, the air cleaner and carburetor stayed pretty clean. If the blowby got too bad, then the carb became an oily mess, but the manifold would stay fairly clean because of the fuel flow washing it. So much for the theory of Positive Crancase Ventilation.

Now we get to the Lightning. Here, the game changes, because there are times when the manifold is seeing pressure rather than a constant vacuum. The Lightning system is strange, at best. Let's start at the bottom. At the bottom rear of the intake manifold is a 90 degree fitting with a hose on it. That fitting is so far down the back of the engine that you can't see it. It is about two inches from the top of the transmission. A hose runs from it up to a tee fitting above the right hand valve cover. That tee fitting has a PCV valve in the bottom of it and a tube running to the intake plenum. Interestingly, all of those tubes (or hoses) have thick foam insulation on them like the factory is worried that they'd freeze or get too hot. Now then, in the bottom of every manifold I've looked at, there has been a few tablespoons of oil - and it pools right where the hose fitting comes into the manifold. So, while are cruising along under vacuum, there will be oily air flow is out the right hand PCV valve and some clean air flow out of the plenum. That air flow will meet at the tee and be sucked down the hose to the back of the manifold where that nifty pool of oil will be bubbling like a jacuzzi as the combined clean and oily air flow passes through it. But....... Now: You hammer the throttle and the boost comes up. Suddenly there is 10 or more PSI in the manifold. So the direction of flow changes and you have 10 or more PSI shoving that nice pool of slime up the pipe and toward the tee. When it gets to the tee, it has to go one way or the other. Since the PCV valve is a check valve it can't go back into the valve cover, so instead, the nice gob of slime heads right into the plenum. From there it goes to the blower and then is hurled at the intercooler, where it slowly coats everything, hurting heat transfer, and then drips back into the manifold to collect and wait for its next trip up the pipe and into the plenum. I don't know about you, but I'm not impressed. But, wait, there's more....... There's a whole other PCV system on the left side of the motor. It is much simpler. It has a PCV vavle stuck in the valve cover grommet and a tube leading to the bottom of the intake elbow. It is that PCV valve that proceeds to fill the intake elbow with oil and also makes sure that the throttle blades get nice and slimy as well. So, how do we fix it? Well, there are lots of folks selling revised PCV valves which have more positive check valves in them. The factory ones do not. So are check valves a good thing? Let's look at the right side first. If it is not a check valve, then the oil gob coming up the pipe under boost can go where it belongs: into the valve cover. But the same 10PSI that sent it there is now flowing full bore into the crankcase - where it then goes to the only place it can get out. Do you know where that is? Why, it is the left hand PCV valve that then sends all the slop it has available to the intake elbow and throttle body and then though the blower, intercooler etc. only to collect in the bottom of the manifold just waiting to be sent out the tube to the right side. The manifold can never drain because it is forever being re-loaded. The poor intercooler does not stand a chance, cause it has slime being thrown at it from two sides.

Ok, so you buy the kit and install the check valve type PCV valves. Then as soon as you hit boost, the crankcase doesn't pressurize, but instead the wad of oil gets shot right into the plenum. I don't think it matters if the left side is a check valve or not. I think it is only there to give the flow under boost a place to go.

The whole problem here is that there is no place in the system that always sees vacuum and as a result everything has to pass through the intercooler. The "drain" at the bottom of the manifold can't just be run to the pan, because as soon as you hit boost, the engine is pressurized. I think the manifold "drain" should have had a valve that opens when the engine is off and lets the oil drain and the PCV port should have been higher so it was out of the slime pool. Putting a one way valve in the line would then prevent the crankcase from being pressurized and only blowby would reach the plenum. There is a high port on the manifold. It is on the left side toward the front. It is actually in the intercooler plate and it is a 3/8 tube. I think that might be a better spot for the left hand PCV to feed, rather than the intake elbow. Run the drain hose to a catch can and eliminate the tee in the right hand line so the right hand PCV valve only runs to the plenum. The system would stay much cleaner, but there's a big problem because under boost, there is no place for blowby gases to go.

So I'll leave you with the theory and my thoughts while I try to invent some real solution to the problem. Any and all input on the matter will be appreciated.

Kern

 

Isn't the problem the baffle, which was removed from the valvecovers creating a stright-on vacum to the PVC causing the oily inercooler ? If Ford put back it should solve the problem !

 

Great write up! The only way to ensure that no oil gets into the IC or the throttle body is to disconnect the lines that run to the plenum, galley and air intake boot. Additionally Clay (Red 92) pointed out the fact that all of that oil mixing with the fuel entering the cylinders is diluting the fuel and lowering the octane which is causing motors to blow on hard acceleration. I agree with him. I would really like to know what the fuel octane rating is once it's diluted by oil. I would be willing to bet the results would be shocking.

As you mentioned the intercooler performance is also affected by the oil saturation.

Here are a couple of threads where the PCV system is discussed in good detail. The first one has photos of my intercooler after Clay removed my blower and there are some posts by other members showing their IC's as well.

The second one gets into more detail on how to disconnect the PCV system so there is "0" oil entering the IC and throttle body.

Hope this is the sort of info you were looking for.

https://www.f150online.com/forums/sh...hreadid=170680

https://www.f150online.com/forums/sh...hreadid=172065

 

Thanks for the links to the other posts. I've seen several suggestions on how to help the problem, but never I really never had a chance to see how the system was actually plumbed. I'm tempted to run the low manifold fitting into a catch can, the right pcv valve to the plenum and set up the left with an oil separating filter . We all hate the mess, but the big factor is the oil coating the intercooler. That hurts heat transfer a whole bunch. I want to keep both the chassis and the intercooler clean!

 

just an fyi, our PCV valve is not really a valve. There is no restriction or one way valve. People are adding those to the L to help keep from pressurinzing the crankcase and sending oil up the drivers side valve cover vent into the intake tube.

The only real way to solve this problem is to install some sort of real baffle on the valve covers or completely remove the PCV system as Red92 has suggested. With the PCV system completely eliminated and installing valve cover vents, there is absoulutely no way for oil to enter the intake. Seperators work to a point but still don't remove all the oil mist from the pcv system.

If Ford had invested some time installing real baffles even the steel wool kind on the fox mustang, it would solve a lot of problems.

 

I have to agree. In spite of my best efforts to engineer a way around it, other than using a single check valve type PCV valve on the right side going to the plenum, a catch can on the "manifold drain" and a vented breather on the left side, I can't come up with a "smog legal" way of fixing the problem. I may put 2 large coalesing filters somewhere down low and plumb the lines through them, but other thats to only solution I can come up with. Catch cans work, but I'd like to be a little more smog compliant if possible...........

 

Simple. Just run the breathers 99.999999999% of the time and revert back to the PCV system for the inspection.

 

there are better ways to be smog compliant....or if I can put words in you mouth...not add to air pollution.


letting crankcase vapors vent is not one of them..... maybe 20 years ago on less efficient engines, but not on our 5.4

think of it this way... whats better, breath the crankcase vapors before or after they are burned in the combustion chamber....

 

Good point, Red 92! I'd much rather breathe 'em before they go through the chamber. And I also agree that with the compromises in the system, breathers look pretty appealling.

But I was trying so hard to be "politically correct".

The trucks are good, but the whole PCV system is a cobbled mess. It is like they designed it to foul the intercooler. Got HP is correct in his statement about the factory PCV valves. They are really only restrictors, because they flow both ways. I can understand why the factory did it, looking at the right side "drain" system. I installed the check valve type on the right and took it out once I realized that it actully made the mess go into the intercooler rather than the valvce cover. I'm thinking a vacuum pump and catch can system. Do the pleated breathers catch enough of the oil to keep the engine compartment clean?

 

No inspections in OK!

 

By just ripping it all off like most of you are saying, you will lose vacuum on your rings. We could learn alot from Kerno if he does a clean instal of the vacuum pump and a catch can that drains the oil back into the engine.

Your on the right track Kerno! Now make one for us so you can become a thousandaire!

 

I have seen a million posts on the subject and I like the way this thread is going. Being skeptical by nature, some of the solutions are very simplistic and potentially could cause problems in the future.

By my observations, a stock vehicle with exactly the right amount of oil (5.7 litres) will not have a big issue with oil. Even going up to 6 litres will be an issue. When the boost goes up, the amount of oil in the intercooler goes up dramatically.

Why doesn't the 03-04 Cobra have this problem even with significantly higher boost? I know the design is different, but is there anything that can be applied to the Lightning to solve our problem?

TB

 

03-04 Cobras do have the same oil ingestion problem, those cars get a lot of oil in the intake.

They have an oil separator mod and they also clean there intercooler when they remove the blower for porting.....many posts on the subject.

http://www.svtperformance.com/forums...splay.php?f=81

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every car with a PCV has the problem at one time or another.
When I had my C5 I had an oil separator set up on the LS1....corvetteforum.com.....


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That is not true at all. Go to some of the forums for the 03/04 Cobras and you will see they have the same problems with oil in the throttle body, intercooler, etc.

You may get every other Lightning or Cobra guy to say they have no problems at all with oil, but most and even mine in stock trim does the same thing.

I tried to also be PC but there is no way unless you install a seperator (that actually works) or install a real baffle in the valve cover. I had thought about putting a baffle underneath the oil fill opening on the pass valve cover and running the pcv valve to the fill tube. That way the oil would have to make a hell of a journey past the baffle and up that tube before it got anywhere near the pcv valve. I would also like to install a one way pcv valve and remove the restriction on the lower intake galley line (at the fitting). This way under normal driving conditions and at idle, the pcv system would work just the way it is supposed to. At boost, the crankcase would not get fed pressure and no oil in the intake boot. You would also eliminate any oil in the intercooler and if any oil does get sucked up, however slight that might be, it would be after the intercooler.

So far the dual breathers idea has been working just fine and have noticed no ill effects as of yet.

 

Has anyone tried one of these from SHM?

SHM oil breather separator