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Lung Mustard Fix

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Old 09-13-17, 10:21 AM
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Lung Mustard Fix

I've ran into condensation and lung mustard in my oil filler tube. After reading several threads, it appears I've hooked up the filler tube fitting wrong - having ran it into the charcoal line. There is no vacuum. I have a K&N air filter, so there's no available vacuum or vent there, but I have a 5/16" fitting available on my RB intake that I'm going to tap. My plan is to run a line directly from the filler tube fitting, with a check valve, to the intake. Obviously, there's vacuum - but are there any concerns with pulling from the oil filler tube directly into the intake? Has anyone done this? Thanks in advance!
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Old 09-13-17, 12:41 PM
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I've read quite a few threads after realizing my car was setup in a goofy, likely non-functional way as well. The tube from my filler tube went to a hole in my (racing beat-style) air box, and the housing tube went to the charcoal canister, so there was no vacuum to create positive ventilation.

The solution that I used was to recreate the factory setup as best I could with parts from my parts car. The housing tube stays connected to the charcoal canister, the oil fill tube hose connects to the factory purge valve, the top line of the purge valve goes to manifold vacuum and the bottom goes to ported vacuum.

There are 2 issues with hooking directly to manifold that I can think of: It does not have any restriction so it will behave like a constant vacuum leak, and there is no protection in case of pressure change/backfire. PCV valves are designed for each engine to prevent these problems; they restrict flow at high vacuum to prevent vacuum leak/idle issues, and are check valves that prevent backflow.

If you can't or don't want to use the factory system, I would recommend getting a PCV valve that will fit inline between your filler tube and your vacuum source. It won't be tuned properly to your engine, but it will be better than not having one.
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Old 09-13-17, 01:31 PM
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Originally Posted by Joekaistoe View Post
I've read quite a few threads after realizing my car was setup in a goofy, likely non-functional way as well. The tube from my filler tube went to a hole in my (racing beat-style) air box, and the housing tube went to the charcoal canister, so there was no vacuum to create positive ventilation.

The solution that I used was to recreate the factory setup as best I could with parts from my parts car. The housing tube stays connected to the charcoal canister, the oil fill tube hose connects to the factory purge valve, the top line of the purge valve goes to manifold vacuum and the bottom goes to ported vacuum.

There are 2 issues with hooking directly to manifold that I can think of: It does not have any restriction so it will behave like a constant vacuum leak, and there is no protection in case of pressure change/backfire. PCV valves are designed for each engine to prevent these problems; they restrict flow at high vacuum to prevent vacuum leak/idle issues, and are check valves that prevent backflow.

If you can't or don't want to use the factory system, I would recommend getting a PCV valve that will fit inline between your filler tube and your vacuum source. It won't be tuned properly to your engine, but it will be better than not having one.
Thanks for the input - does the oil filler actually need a vacuum, or does it just need to be able to vent? It seems internal engine pressure would be enough to prevent build up, as long as it can breath with a check valve...

I've seen some run the line directly to air cleaner covers, including RB's setup. I'm assuming these hookups are outside the air filter itself and do not have a PCV valve (at least the RB hookups).
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Old 09-13-17, 02:04 PM
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I think the need for positive ventilation is just a matter of the effectiveness, the vacuum actively sucks the humid air out of the crankcase, removing more moisture in a predictable direction.

One of the main motivators for me to change the routing was the way the charcoal canister is supposed to work. The tank vent fumes are supposed to be stored in the canister, then those stored fumes are supposed to be sucked by vacuum through the PCV system into the intake when the car is running. No vacuum, no fume removal.
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Old 09-14-17, 03:00 PM
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Oil fill tube nipple should get one of those small cone filters you can get at advance auto/pep boys/etc. It is maybe $10.

Nipple on the center iron gets a 5/16th fuel/vacuum line and that goes to a port on the manifold for vacuum.

Some add a PCV on the iron line, I used one from a 90's dodge caravan.
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Old 09-14-17, 04:04 PM
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Originally Posted by Jeezus View Post
Oil fill tube nipple should get one of those small cone filters you can get at advance auto/pep boys/etc. It is maybe $10.

Nipple on the center iron gets a 5/16th fuel/vacuum line and that goes to a port on the manifold for vacuum.

Some add a PCV on the iron line, I used one from a 90's dodge caravan.
Thanks for the input! This has been confusing as **** - I suppose based on a million different setups...

I run a Weber with a K&N filter setup, there's nothing to mount a line to for the oil filler neck (which is one way I've seen it done).

I have a RB intake that has a secondary vacuum port. I'm inserting a Fram FV333 PCV there. I'm T'ing the filler and crankcase to this valve. I'm also T-ing the crankcase into the charcoal canister - so that ultimately all three run into the intake manifold.

I've read where this will create a vacuum leak, others some it won't. If it don't work - I'm going with the breather idea. I run primarily on the highway, so I think heat and venting alone will prevent the gunk buildup...
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Old 09-21-17, 10:13 AM
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So - the master plan did not work. I was able to pull vacuum from the RB intake manifold - and had it hooked up to the oil intake. BUT - with the crankcase hooked up to the charcoal canister, I believe the crankcase may not be able to breath and I'm still getting condensation.

To anyone who knows - for those of us who have no original carb, intake, emissions equipment left (or just simple idiots like me) - can the crankcase vent and oil filler vent be summed up in that the crankcase needs fresh filtered air and the oil filler tube needs a vacuum?
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Old 09-21-17, 03:11 PM
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I was trying to find the images of an installed setup, but what I did was install a tee in the vacuum line that goes to the intake manifold, run a line from the Tee to the lower nipple on the engine, i added a pcv valve in the line, and then added a little air filter for the nipple on the oil filler neck.

This way the air gets sucked in via the upper nipple on the oil filler tube and any condensation is then sent through the vacuum line with the pcv valve into the intake, no more yellow lung mustard. also I do not run the charcoal canister and it has been removed from my engine bay.

Last edited by rayadas; 09-21-17 at 03:13 PM.
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Old 09-21-17, 04:44 PM
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Originally Posted by rayadas View Post
I was trying to find the images of an installed setup, but what I did was install a tee in the vacuum line that goes to the intake manifold, run a line from the Tee to the lower nipple on the engine, i added a pcv valve in the line, and then added a little air filter for the nipple on the oil filler neck.

This way the air gets sucked in via the upper nipple on the oil filler tube and any condensation is then sent through the vacuum line with the pcv valve into the intake, no more yellow lung mustard. also I do not run the charcoal canister and it has been removed from my engine bay.
That actually helps - filtered air in one line, the other line vacuumed out. Thanks!
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