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PCV Catch Can

2000StreetRod

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The excessive build up of crud on my throttle body and intake air plenum concerns me and I'd like to prevent it. There are numerous threads on this forum about adding a crankcase breather and plugging the intake hose PCV inlet. Being somewhat of an environmentalist I'm seeking a more earth friendly solution.

Has anyone tried an oil catch can similar to those used on Saabs and Volvos?
 



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celly

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I'm pretty sure there are many "oil separator" threads on the site. I seem to recall both Aldive and Rick had threads on the subject. Might want to search around and see how they made out.
 






corkey

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why not put a catch can kind of deal inline fromthe pvc to the throttle body, like the way a fuel filter fits in ?
all it has to be is hollow ,and bigger around than the hose, and all the oil will fall in, and stay in,. just mount it sideways, or horizontal,
 






2000StreetRod

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I'm pretty sure there are many "oil separator" threads on the site. . .

Thanks! I did a search but called it the wrong thing. From the threads it appears to be stock on some or all of the Rangers. I'm adding an oil separator to my list of planned mods.
 












celly

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Anyone ever done this mod on the 5.0? I see a lot of info on OHV and SOHC 2nd gens.
 






storlied

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Oh I wouldn't ask that question...
 






celly

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storlied

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Everyone, mainly Aldive flipped out on me when I brought this up for the 5.0L stating I don't need to worry about it because I don't have a SOHC... something to that nature, it was awhile back.
 






celly

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Everyone, mainly Aldive flipped out on me when I brought this up for the 5.0L stating I don't need to worry about it because I don't have a SOHC... something to that nature, it was awhile back.

Methinks you "misinterpreted" their responses. Let's just leave it there. ;)
 






storlied

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Heh, alright.. enough said on that matter. Anyways, I think it would be a benificial mod on any of these engines really, I've seen just how messy the TB can get from the oil. It's been said that the oil that runs through there can actually help the engine and TB, I don't know how much truth there is to that statement though.
 






celly

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Anyways, I think it would be a benificial mod on any of these engines really, I've seen just how messy the TB can get from the oil.

Agreed.
 






2000StreetRod

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Valve Cover Vent Flow Direction

On my SOHC there is a hose connecting a port on the passenger side valve cover to a port on the main air intake hose. I assumed that oily fumes (blow-by gasses) from the crankcase flowed from the valve cover to the intake hose to be burned and these gases were responsible for the crud accumulated on my throttle body and the walls of my intake air plenum. If so, then an oil separator inserted in the hose path would be beneficial. Further investigation (search for a pcv valve) revealed that the valve cover port is intended to be an inlet instead of an outlet and an oil separator would be of no benefit. According to my Haynes Repair Manual "If abnormal operating conditions arise, the system is designed to allow excessive amounts of blow-by gasses to flow back through the crankcase vent tube into the air cleaner . . ." That may be the case for my Sport but the solution is to continue my quest to locate and replace the PCV valve.
 






storlied

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How would it be an inlet unless it was designed to take the air sucked by the engine though the intake? But the way its all setup it only works as an outlet for gasses and pressures.. air flow in the intake, in any part isn't ever gonna just reverse.. an oil seperator Will help.. the evidence is all over your TB.. it's sucking all the oil through the air intake, and even worse when you have your engine at WOT a lot.. You could always use a breather filter, and seal the hole in your intake.
 






2000StreetRod

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SOHC PCV Air Flow

How would it be an inlet unless it was designed to take the air sucked by the engine though the intake? But the way its all setup it only works as an outlet for gasses and pressures.. air flow in the intake, in any part isn't ever gonna just reverse.. an oil seperator Will help.. the evidence is all over your TB.. it's sucking all the oil through the air intake, and even worse when you have your engine at WOT a lot.. You could always use a breather filter, and seal the hole in your intake.
The PCV system on my SOHC is designed to draw filtered and metered air from the air intake tube which enters the crankcase via the passenger side valve cover port. The air flows thru the crankcase and exits thru the PCV valve located at another port somewhere near the top rear of the engine. After exiting the PCV valve the blow-by gasses enter the intake air plenum. I believe the PCV valve closes when vacuum is high (idle) preventing the normal flow. Installing a breather at the valve cover port would allow the flow using poorly filtered and unmetered air from the atmosphere. Except possibly at idle, under normal conditions, you would not see fumes exiting from the breather like in the old days before PCV valves. If my PCV valve is clogged, then the normal flow would be blocked and the valve cover port would act as a vent. That's why I'm trying to find my PCV valve (it's location varies by year and model) and replace it.
 






2000StreetRod

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SOHC V6 PCV Valve Location?

I have reviewed the various PCV valve locations identified in posted threads but could not find mine in the corresponding location on my 2000 Sport. This morning I noticed a photo in my Haynes Repair Manual that shows the lower intake manifold with the upper intake air plenum removed. There appears to be a PCV valve with a T or V splitter exposed. It would be located directly below and aft of the 1997 variable induction system (VIS) intake manifold tuning (IMT) valve vacuum diaphragm connection (I don't have this on my 2000). Below is a photo taken from the passenger side of the area. The possible valve is marked with an arrow.
VALVE.JPG

Can anyone confirm that this is the PCV valve?
 






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On my SOHC there is a hose connecting a port on the passenger side valve cover to a port on the main air intake hose. I assumed that oily fumes (blow-by gasses) from the crankcase flowed from the valve cover to the intake hose to be burned.......... According to my Haynes Repair Manual "If abnormal operating conditions arise, the system is designed to allow excessive amounts of blow-by gasses to flow back through the crankcase vent tube into the air cleaner . . ." That may be the case for my Sport but the solution is to continue my quest to locate and replace the PCV valve.

That is a very common misconception. And as usual, Haynes is full of crap. Horrible source of information.

The PCV system is designed to take FUMES from the crankcase that can (1) pollute the atmosphere and (2) harm your engine. It then re-introduces them to the combustion chamber to burn off. Remove your PCV and watch all kinds of problems pop up...including a milkshake substance on the insides of the valve covers, etc from moisture that is not boiled off and removed by the vacuum process of the PCV. This also is true from resulting acids that develop in the crankcase and can eat bearings and pit surfaces such as camshaft lobes. The PCV system is a very critical part of an efficient engine and manufactures have had them since every member of this forum was in diapers. They used to be called draft tubes...

The tube you see on the valve cover (on a 5.0 for example) that goes from the oil fill spout to the air inlet ducting is NOT a breather. However, it can tend to work out that way. Remember...if your PCV is drawing air OUT of the crankcase...that air needs to be replaced or you have a vacuum in the crankcase. A crankcase under vacuum is a good thing...but not necessarily in this case. What we want is airflow through the crankcase. So air must come in the crankcase from somewhere...and that tube is it. If you will notice...that air is metered. In other words, it is taken AFTER the MAF sensor. That is because we want the ECM to know ALL the air that the engine is seeing. Remember...the PCV is taking that air and introducing it to the combustion process via the intake manifold.

Where things really get screwed up is when you (a) get a bunch of blow by from poor piston ring sealing, or (b) your pcv picks up a bunch of oil in suspension. The second is usually poor design by the OEM. In this case, a catch can is very beneficial. If you get one designed for the purpose, you will see it's more than just a place to hold oil. It actually has provisions to help drop the oil out of suspension. These cans are becoming more and more popular as horsepower levels increase...especially in supercharged cars such as the Cobra. If you are getting a lot of oil in the tube from the oil filler to the air intake, I would suspect another problem such as excessive blow by or a faulty or missing PCV system. That tube should have air pulling AWAY from the intake...not towards it. (in most situations)

In summary, if you feel you are having oil passed through your PCV system, install a well designed catch can in the line between the vacuum source and the PCV valve. Do NOT install a breather in the fresh air line between the inlet tube and the valve cover. You will introduce unmetered air to the combustion process.
 






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Catch can is a common mod on the Machs and Cobras. I did a writeup on how to install one here near the end of page 2.
 









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2000StreetRod

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I think we agree

That is a very common misconception. And as usual, Haynes is full of crap. . . .
The PCV system is designed to take FUMES from the crankcase that can (1) pollute the atmosphere and (2) harm your engine. It then re-introduces them to the combustion chamber to burn off. Remove your PCV and watch all kinds of problems pop up. . .
The tube you see on the valve cover (on a 5.0 for example) that goes from the oil fill spout to the air inlet ducting is NOT a breather. However, it can tend to work out that way. Remember...if your PCV is drawing air OUT of the crankcase...that air needs to be replaced or you have a vacuum in the crankcase. A crankcase under vacuum is a good thing...but not necessarily in this case. What we want is airflow through the crankcase. So air must come in the crankcase from somewhere...and that tube is it. If you will notice...that air is metered. In other words, it is taken AFTER the MAF sensor. That is because we want the ECM to know ALL the air that the engine is seeing. Remember...the PCV is taking that air and introducing it to the combustion process via the intake manifold.

Where things really get screwed up is when you (a) get a bunch of blow by from poor piston ring sealing, or (b) your pcv picks up a bunch of oil in suspension. The second is usually poor design by the OEM. In this case, a catch can is very beneficial. If you get one designed for the purpose, you will see it's more than just a place to hold oil. It actually has provisions to help drop the oil out of suspension. These cans are becoming more and more popular as horsepower levels increase...especially in supercharged cars such as the Cobra. If you are getting a lot of oil in the tube from the oil filler to the air intake, I would suspect another problem such as excessive blow by or a faulty or missing PCV system. That tube should have air pulling AWAY from the intake...not towards it. (in most situations)

In summary, if you feel you are having oil passed through your PCV system, install a well designed catch can in the line between the vacuum source and the PCV valve. Do NOT install a breather in the fresh air line between the inlet tube and the valve cover. You will introduce unmetered air to the combustion process.

I believe that you misunderstood the purpose of the Hayne's quote. It was to point out that during normal operation the air flow is from the main intake tube to the passenger valve cover via the connecting hose. It is only during abnormal circumstances that the flow is in the opposite direction. As you point out, "So air must come in the crankcase from somewhere...and that tube is it."

There is at least one thread on this forum that debates the impact of plugging the hole in the main intake tube and installing a breather on the valve cover port. In my opinion, under normal circumstances, this does not result in air pollution since the port is an inlet. I agree with you that the air entering the crankcase via the breather is unmetered and could result in a leaner mixture. However, it is very possible that during closed loop operation, the O2 sensor feedback will cause the PCM to compensate.

I'm not familiar with the 5.0L but for the SOHC the photo in my previous post indicates the PCV valve. There is a Y connection at the top of the valve. One hose goes to a port on the bottom of the left intake air plenum and the other goes to a port on the bottom of the right intake air plenum. The absolute air pressure in the intake plenum is less than the ablsolute pressure in the main intake hose resulting in the desired flow direction. If the PCV valve is blocked (which may be my situation as you accurately point out) then the least resistance path to relieve crankcase pressure is from the valve cover to the main intake tube.

I agree that adding a catch can (oil separator) is a worthwhile endeavor but it should be between the PCV valve and the two intake air plenum ports - not between the valve cover and main air intake tube ports.
 






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