View Full Version : Installed 2nd Separator on PCV and...

10-04-2006, 12:19 PM
...it is capturing the same amount of oil as the first one! With roughly 200 miles, the one separator caught, say 2 ounces of oil. Now with 200 miles again, both separators (inline with one another - perhaps I will try parallel)) caught 2 ounces each!


10-04-2006, 01:36 PM
I thought about doing that too. I have the steeda seperator and was going to add the jlt or make one. I am not getting near that much oil though.


10-04-2006, 04:10 PM
I don't know if being boosted makes a difference.

Those little air/oil separators are $12 at Home Depot, BTW. The tubing is 3/8" fuel line, which is also inexpensive, along with a couple of 1/4" thread x 3/8" barbs.

10-05-2006, 07:06 AM
I have a 98 and my oil has just started going away ( 75,000 miles ). The hose from the pcv valave was wet and I changed the pcv valve. The oil consumptiom slowed down but it still is going away slowly. I do not have a blower. Is this normal for NA engines too? Just a note, I put a new pcv valve on for maintainence purposes from Auto Zone. It started sucking up oil so I bought one from Ford and it slowed but still is drinking some.

10-05-2006, 07:26 AM
I have used the fuel line but was warned by Napa about its use where I was putting it. They claim that the heat and oil would cause it to break down or dry out. The same goes for the 5/8 heater hose for the breather side. I have seen at car shows where someone used transmission cooler hoses and since they are made for heated oil trasfer they will not become degraded and are more rigid than the fuel line or heater hose. If you use fuel line or heater hose, make sure you inspect them every so often as part of routine maintanance so you can prevent an issue down the road just in case NAPA was right about the brake down issue.

From my experience with my 01 Cobra, where I started use of the air/oil separator which seemed to work as it would fill up within 100 miles, I decided after getting the 04 not to wait until it becomes a problem so I installed the same type of seperator on the 04. One thing I did notice with the air/oil separator when used on the PVC line was an increase in oil in the intake pipe. After that I installed an SHM breather filter but that did not stop the oil pooling in the intake pipe, it was reduced but still an issue. At that time I had removed the air/oil separator and from that point onward I did not find oil in the intake side. I did not think of putting the two together but once you think about it, the air/oil separator will place a flow restriction in the PCV system. If you place one on the PCV line, you should also put one on the breather line to balance out the flow rates even if the secondary does not fill up with oil.

10-05-2006, 11:28 AM
Secondary, meaning the passenger side valve cover's breather line? Yes, that will be the very next thing I do!

10-06-2006, 07:09 AM
I have a 98 and my oil has just started going away ( 75,000 miles ). The hose from the pcv valave was wet and I changed the pcv valve. The oil consumptiom slowed down but it still is going away slowly. I do not have a blower. Is this normal for NA engines too? Just a note, I put a new pcv valve on for maintainence purposes from Auto Zone. It started sucking up oil so I bought one from Ford and it slowed but still is drinking some.
The issue with oil consumption through the PCV system has been an issue since it was first used in the mid 1970's. Probably not much of an issue then as it is now since the engine technology has changes and higher compression motors are finding their way into the automotive market. The industry has not evolved the PCV system so there tends to be a problem. This issue affects both push rod engines as well as overhead cam engines. Having overhead cams requires a high oil flow to lubricate the cam bearings so there are more oil jets involved. The other issue resolves around baffling and how the breather line is connected as well as the PCV line. This brings me back to my first overhead cammed vehicle which was a 1.9L HO Escort GT. I had found oil in the intake, in the plenum, and the breather line which came out to the air box and had its own filter and was usually saturated with oil. At that time I had no clue what could be done to correct the problem but one thing for sure I used alot of carb cleaner to flush it out at every oil change.

As far as our engines are today, the old PCV system does create a problem since it flows too much. I do believe that my NA 2001 Cobra had more of a problem with the oil entering through the PCV line than it did with the breather as a source. I did try using two on the 01 but the breather line did not seem to be the source for the oil passage like the PCV line was. When it comes to power adders, they tend to create more vacuum pressure on the low pressure side once they are supplying boost to the plenum. The type of blower used has an impact on how the oil will enter the intake. Terminators (roots type) develop boost pressure in the bottom plenum and once the boost bypass valve opens (when the throttle closses abruptly, as in shifting gears) the impules of air pressure in the upper plenum will force oil out through the breather line before the PCV valve has a chance to close. Roots style blowers tend to pull vacuum on the PCV line during boost and reverses flow once it dumps the pressure. Centrifugal types compress the air before the throttle body so the entire intake plenum (after the throttle body) is under boost pressure which tends to pressurize the PCV line which would force oil flow out through the breather line since it is seeing more of a vacuum created by the impeller of the supercharger. Once the throttle body closes, the boosted intake pipe needs to be dumped back into the metered low pressure pipe where the breather line is connected. At this point, the PCV system is flowing from breather to PCV valve. Any oil that was pulled out of the breather line will sit in the low pressure intake pipe and will be drawn to the source of vacuum (IAC line) or flow out to saturate the air filter.
The amount of oil movement out of the crankcase is not much at any given point in time, however over a period of time the small amounts of oil passing into the intake adds up to considerable amounts. A good PCV system is one that would only pull out combustionable vapors and equalize the crankcase pressure and leave the oil where it should be. The more advanced PCV systems which are extremely expensive do exist but are intended for use with piston powered aircraft since they experience variations in air pressure far greater than what you would encounter on the ground. In some cases, you may find some well designed PCV systems used in some exotic vehicles and in a few German vehicles they have developed some interesting valve cover baffle systems that will separate the air from the oil. I think I spent too much time searching the internet for a solution to the problem. The air compressor air/oil separators do work but only for a short time since the associated pressures of the PCV system are low in comparrison to air lines from compressors as well as the difference in the amount of oil saturation from the crankcase as compared to the oil saturation from an air compressor.

10-06-2006, 07:20 AM
Secondary, meaning the passenger side valve cover's breather line? Yes, that will be the very next thing I do!
That is what I meant. When you install one on the breather line, the arrow on the oil separator should be pointing toward the intake pipe so that the trapped oil stays on the side connected to the valve cover. Air will flow through the filter in both directions since it does not have a built in check valve. The PCV valve should be the only check valve in the system otherwise the pressure in the crank case would increase if you were to block off both valves at the same time. I thought about doing this but was warned of the concequences. Pressure build up in the crankcase would tend to increase the amount of oil passing the rings on the pistons.

This does not mean that you cannot use breather elements in place of the PCV system. If you go the breather element route on both valve covers, best method is a canister type breather that has a catch can at the bottom of it and the valve covers connect to the cannister. The problem with the small breather filters you can find at any autoparts store is that they tend to saturate with oil very easily which will find it way onto the outside of the valve covers. Not to mention the smell, it is a mess unless you spend the money on a catch can style system intended for racing. Just remember to return to the PCV system at time of state inspection since removal of the PCV system is not EPA compliant.

10-06-2006, 08:51 AM
These canisters...where do we get these? Also, I wonder how long these little filters will last? I guess simply monitoring the amount collected per tank of gas is one way.

And to correct an earlier post...the 3/8" tubing I am using is, in fact, transmission line, not fuel. My fault. It is certainly more rugged tubing!

10-07-2006, 11:18 AM
Here is what I found on the net for oil breather catch cans.





Considering if they are used with just the air filter, they will not be street legal. But so is changing the mid pipe or removing the cats.....

Since the breather canister uses an attachable air filter element, it could be removed and a hose connected to it that would connect to the breather line of the intake pipe. They come in many styles and fitting arrangements. If you opt for the dual connection type tank it would allow you to connect one tank to both valve covers. If you opt for that, you would have to cap off the PCV fitting on the plenum with a rubber plug and hose clamp.
The problem arises since the idle control speed may be affected without the PCV valve in place. Perhaps just one tank for the breather line with a single connection to the valve cover on the passenger side along with the air/oil separator on the PCV side would work and would reduce the amount of potential oil found in the intake. Based on the current PCV system, there could be an issue since the pressures associated with each valve cover is not the same. Since the block is not completely full of oil, the path of vapor flow from one side to the other is throught the timming chain cover as well as the oil passages throught the valve covers to the block. The thought comes to mind if there was a common external line connected to each valve cover would that reduce the ammount of oil entering the intake through the PCV line and breather line?
Also, how would that affect idle speed? This is under the assumption that the PCV valve will still be used. Only one PCV valve is necessary and should be connected to the plenum. I think I will do some experimentation to see what happens. I will come back with my results.

10-07-2006, 01:22 PM
Looked for the extra parts I had laying around and could only find one breather filter which was okay since the SHM breather line filter is essentially the same thing. Found the old original plastic PCV valve and removed the plastic elbo. I attached the PCV into the breather hose and connected a 4 foot section of 3/8 fuel line I had used with the air/oil separator. I removed one of the 90 degree brass fittings that was used on the air/oil separator and inserted the threaded end into the PCV line that enters the intake plenum and the other end of the brass fitting connected to the fuel line. Placed the small breather element where the PCV valve sat on the driver's side valve cover (did not fit all too well which was too loose to take a test drive.) Turned the car over and it started right up like it normally does. Let it warm up and and the idle speed was not affected by the change to the PCV system. Several shots of throttle did not seem to pose any problems and the idle speed returned to normal. Keep this in mind that the 04 has an improved dash pot setting so the RPM's will drop rapidly to idle speed as compared to the 01 which tended to wander a bit or hang slightly before dropping down to idle.

Without a doupt, a dual feed single breather canister could be used as long as you can fabricate a means to connect the breather line and PCV valve to it. In doing this, there still would be the EPA vapor management as well as keeping the oil where it belongs since the change in the PCV system would not be forcing air flow through the block. Any oil vapors that may flow out of the valve cover would be recovered in the catch can. :thumbsup:

10-08-2006, 10:22 AM
I did a bit of surfing this morning and found this article to be of interest which describes how the PCV system works . Even though it was based on Toyota, it is a good description of the PCV valve. Once you get beyond the first page, the functions of the PCV valve are described under no load, low cruise and full throttle high load conditions.


Technically, most of the blow by gasses contains unburned fuel. The PCV system is designed to draw that out of the crankcase and return it to the combustion chamber. Placing a restriction on the PCV valve may reduce the amount of vacuum applied to the valve which would increase the flow through the breahter tube. The air/oil separator does seem to work to some degree, but it may not be all that good if the PCV valve is not operating like it should. Also what I suggested earlier is to place the same restriction on the breather line to balance out the pressure differentials. The object was to trap oil but this could also lead to increase crankcase pressures. Once the element in the air/oil separator becomes saturated, the flow of gasses is reduced. In addition, the air/oil separator also increases in temperature and the associated gasses or hydrocarbons may not be compatible with the materials used in the separator.

A better method would be to employ a free flowing system that would trap fluids and still remove vapors as well as function as originally intended. Some of the breather filter canisters may be used to improve the PCV system and still remain EPA compliant. The missing part is a filtered coupler to connect to the catch can as well as the breather line and pcv line. A single port canister can be used if use a T or Y coupler to connect the two lines from the valve cover together. It would be nice if someone like moroso, Jeggs, Canton racing, or whomever would create such a canister. I think I will send at least one of them an email and see where that ends up......