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Alex - you need to have the vacuum line hooked to the tank to relieve pressure build up from crank case. I tried this (what you want to do) and had blow by oil coming out top tank vent (little "U" hose)
You need to run prebutterfly to filter catch can and post butterfly (vacuum) line to a nonvented catch can that is designed to catch oil and allow only air to be drawn into intake manifold.
@gus, got it. i have non vented catch can - beer can size. so use this for the small intake correct? for the large one, i can just plug the intake and vent the large intake hose to atmosphere or into a different catch can? thanks for clarifying
@gus, got it. i have non vented catch can - beer can size. so use this for the small intake correct? for the large one, i can just plug the intake and vent the large intake hose to atmosphere or into a different catch can? thanks for clarifying
Alex, I don't think that will work as you will have vacuum leak from the larger hose to the oil tank and to the smaller hose connecting after the throttle.
I think that we can only do it in 2 ways:
1. maintain all stock but just add an oil catch can in the middle of the smaller hose from oil tank to intake after the throttle
2. plug both hoses at the intake, vent both of the small and big hoses from the oil tank to open air.
Any comment if my think is correct please?
Cheers
@95993 i got a cheapie oil catch can that i will use and it should be perfect to reduce / minimize the oil in the intake... will have to be a spring job...
Ok - am rebuilding my engine so I have some good pictures of my oil line system from the crank case etc. First picture shows the crank case breather line that goes directly to the oil tank. Am going to install a one way valve in this line to restrict back flow of air. The second line shown is the line from the top of the oil tank to the vacuum intake on the manifold after the butterfly. This line is connected to a sealed oil catch tank with a visible exterior line to see oil level in the catch tank. The silver canister is the vent to outside air for the tank to reduce tank pressure and catch any oil vented out from the tank. System seems to work well, you can see a little oil level in the check line on the vacuum return tank side. Hope this clears up some questions.
Ok - am rebuilding my engine so I have some good pictures of my oil line system from the crank case etc. First picture shows the crank case breather line that goes directly to the oil tank. Am going to install a one way valve in this line to restrict back flow of air. The second line shown is the line from the top of the oil tank to the vacuum intake on the manifold after the butterfly. This line is connected to a sealed oil catch tank with a visible exterior line to see oil level in the catch tank. The silver canister is the vent to outside air for the tank to reduce tank pressure and catch any oil vented out from the tank. System seems to work well, you can see a little oil level in the check line on the vacuum return tank side. Hope this clears up some questions.
Gus, really appreciated your explanation and pics.
The line that now goes to your sliver tank, it was connected to the intake before the butterfly but after the MAS, so all the air in or out that hose is measured by the MAS in a stock closed venting system.
In your current setting, will it introduce any unmeasure air into the system to make the engine running leaner?
Does anyone know why 2 hoses (before and after butterfly) are needed in the stock venting system?
No, the hose (air) that goes to the silver tank now that was connected to the manifold prior to the butterfly, but after the MAS did not have its air flow measured. The air flow in the hose came directly from the tank and in reality was just an open line to the static out side air, but captured within the intake air flow. In a way I have duplicated this by venting to the outside air but controlling or capturing what oil is pulled or forced from the oil tank. This is at a minimum. The more critical line is the smaller hose that is wafted the butterfly and used to create a vacuum on the tank pressure. Here I believe it is critical to keep this line but have a closed system that can capture in oil drawn through the hose from the tank into a remote reservoir that allows air flow, but holds the oil. I get about 1/2 to 3/4 inch of oil in the tank i use after a full DE weekend.
I need to point out that I am running a vary or am with a after market ECU that does not need a MAS. But either way the air that passes through the hoses is not measured by the MAS.
Gus, really appreciated your explanation and pics.
The line that now goes to your sliver tank, it was connected to the intake before the butterfly but after the MAS, so all the air in or out that hose is measured by the MAS in a stock closed venting system.
In your current setting, will it introduce any unmeasure air into the system to make the engine running leaner?
Does anyone know why 2 hoses (before and after butterfly) are needed in the stock venting system?
Cheers and Merry Christmas to you all.
The hose before the butterfly is the source of filtered air drawn into the system. The hose after the butterfly is a vacuum source. IIRC the tank has a much smaller hole than the hose size. It is essentially a metered air leak around the butterfly. An engine with excessive blowby would push air out both hoses instead of filtered air being drawn into the system. These hoses are the source of the "never keep the oil tank full advice". Because there is a constant suction towards the intake, oil sloshed into the vent hose gets sucked towards the engine. My fix was to use a Mann ProVent air oil separator that is originally designed for Diesel engines. I ran across it when I saw it being used by Lingenfelter on really high horsepower supercharger vettes. They sell it, but it can be found for about half price from various diesel parts suppliers. Mine is the smallest size, plumbed into the suction hose. It is black, and some type of high heat plastic that fits in with everything else in the engine compartment. Looks like it could have been a stock Porsche part. Best part is that it is meant to be self draining, with a low pressure one way valve that I plumbed into the crankcase vent cover.
I keep my oil tank full now and never leak a drop.
This is what it looks like, I used a ProVent 100. I would have liked to use a larger size, but space is severely limited. The unit has a drain nipple on the bottom, which is funnel shaped. It is primarily intended to drain into a sump, below oil level, but that isn't possible on our engines without adding a connection to the oil tank. The other way to drain it is to used their low pressure one way valve in the drain line. The column of oil in the line will open the valve and drain it into the engine, but not allow crankcase pressure to go back into the drain line. This method requires a minimum distance that the separator be installed above the valve, which is why I have it so high. I put a nipple on the crankcase vent cover to attach the drain hose. Installed as it is, it is at the minimum distance above the valve, but seems to be working fine. The hose nipples on the ProVent are pretty large, but I found a brass reducer at a hardware store that is made for Pex pipe that pressed into the nipple and fits the factory hose perfectly. It fit where I have it without cutting any of the factory hoses, I only had to add a hose from the unit to the intake, and a hose to the drain valve.
If I were starting from scratch with the engine out, I would use a larger size, and add a return line to the oil tank. It could be easily hidden behind the intake. If you look at the Mann manufacturer website, they have many configurations with different mounting styles and hose outlet directions. There is a replaceable filter element inside. The style I have has moulded in mounts, but they aren't needed. If I had clamps that matched the factory, and removed the sticker, it would match the normal rats nest of hoses on a 3.6 and not even be noticeable. My engine hasn't dripped a single drop of oil since I installed this.
06-21-2017, 12:23 AM
