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What is this filter for and why would someone do it?

2K views 21 replies 7 participants last post by  semperfido 
#1 ·
Ive owned my car for about a month now..can someone tell me what the purpose of this filter would be for? there is a line that goes from the bottom of air filter, to this small little filter in the line, then the other end goes to the right side (left side view) valve cover.

the in-line filter then dumps out the bottom of the car, and there are portions of the frame covered in the gunk that this dump valve releases.

is this filter necessary or on there for a reason? if removed, what could i put in the valve cover instead? and would i then need to change the air filter so that it does not have the hole associated with the hose seen here?

thank you!
 

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#2 ·
i have learned that the valve on the passenger side valve cover is called a PCV. this PCV runs to this filter put on by a previous owner, the filter then runs to the bottom of the air filter.

the driver side valve cover has a breather cap that goes to the intake, which i believe is normal. what i am questioning is this passenger side with the filter in-line.
 
#3 ·
The hose from the bottom of the air cleaner to the driver side valve cover is for fresh air to go into the engine. The passenger side is the PCV valve to release excess pressure and blow by. The picture is small so difficult to tell what it is but I believe it's an oil catch can. The blow by is made up of oil and gas, well, that's what my blow by is consist of anyways. The catch can is there to trap the blow by. If you don't want to use the catch can, you can just have the hose go directly from the PCV to the carb or spacer with PCV port, whichever setup you have. I have a catch can on mine because I have excessive blow by. Hope that helps.
 
#4 ·
As QBUI stated the hose from the pcv valve should run to the pcv port on the carb or spacer plate. I believe you are saying it runs to the air cleaner and that is wrong. The driver side should have a breather in the valve cover. Plug the hole on the air cleaner or if the breather on the driver side has a provision for a hose run that to the air cleaner. The filter should no longer be needed as it looks like an attempted cure for the improper pcv routing.

Rick
 
#8 ·
So here is how it is setup...it is a 302 in a 65 coupe (someone converted it from a 6 cyl)....the drivers side oil breather cap hose is connected to the back of the carb (just underneath, so probably the spacer)...the passenger side valve cover has a PCV valve, connected to an in-line filter that dumps out of the bottom, and then continues to be connected to the bottom of the air cleaner.....

from looking at other photos and some suggestions, is this opposite? should the drivers side breather be connected to the air filter, and the passenger PCV be connected to the back of the carb/spacer valve?
 
#9 ·
Yes, I believe it's backwards on your car. The passenger side PCV should be connected to the carb spacer. On the driver's side valve cover, breather oil fill cap or fill cap with a connection to the air filter (to create a "closed" PCV system).
 
#10 ·
is it as simple as just removing the connecting tubes and reversing them? or is there more to this than that?

also, switching them back the way they should be, will this allow me to remove the in line filter the previous owner installed? maybe they were unaware the connections were backwards.
 
#11 ·
the in-line filter then dumps out the bottom of the car, and there are portions of the frame covered in the gunk that this dump valve releases.
It sounds like your oil separator/oil catch can is actually trapping a significant amount of oil. You might want to keep it... though I'd fit it with a drain petcock or replace it with a unit that incorporates a manual drain. Empty it at each oil change. It's bad to dump that gunk back into your intake.

Of course, some members will surely "express their opinions" and beat you up for even considering an oil separator. I will say that too much oil out of your passenger side valve cover could be indicative of a problem... it's either excessive "blow-by" or valve covers with poor (or no) baffles.
 
#12 ·
It has been on there for some time, at least 5-10 years.
The gunk build up does not seem excessive for the amount of time it has been on the car.

My main question/concern is whether this whole system is hooked up properly or not. From my observation, and others, it seems to be it is backwards? the air filter is connected to this filter (with the dump valve, and it does have a manual option to empty it), and then the other end goes to the PCV on passenger side valve cover.

the oil filler cap is connected to the intake/carb spacer.

is this setup correct or backwards?
 
#13 ·
Ford talks about oil separators used with PCV systems in this article

http://www.mustangtek.com/Library6/PDF/ShopTips6-10.pdf

You'll have to decide for yourself. Looking at your posted pic, I think that catch can might just be an air compressor filter. If it's fitted with 1/4" hose barbs, it's not sized ideally to your lines (3/8" ID, I believe). Also, most of those compressor filters use polycarbonate bowls; also not ideally suited to a harsh automotive application. If you choose to use an oil separator, you should probably look for a better one. I'd get a baffled unit with a glass or metal bowl, 3/8" hose barbs, and a drain petcock.
 
#15 ·
I believe that your setup is backwards (passenger side valve cover/PCV should go to carb spacer and driver's side valve cover should got to air filter housing).
 
#16 ·
show us a pic of the oil filler cap. I have a memory of an engine pic posted in the past week that showed a PCV valve in the top of the oil filler cap. It might have been your car. In which case the hose from the filler to the carb space would be correct. Backwards from how Ford did it but not wrong.
 
#19 ·
look at that photo closely, it looks to be a PCV in the oil filler cap...but if this is correct, and it is connected to the correct valve, why would i be having blow by be dumped out of the filter on the other valve cover tube, when it should be flowing the opposite direction?
 
#20 ·
Grab the hose on the filler cap and pull. Confirm there is a PCV valve there.

When I first got my 66 it had the "Open" PCV system. There was all kind of oil and grunge on the valve cover below the Oil fill cap. The mesh in the cap was soaked with oil and would drip out.
The engine had 90k miles and was a bit tired and had a good amount of blowby.

Guess that is a way of saying the catch can is there because the motor is wore out.
 
#22 ·
Guess that is a way of saying the catch can is there because the motor is wore out.
Not necessarily, but it would be nice to see if the PO installed the catch can as a preventive maintenance measure or if he/she was trying to fix a worsening problem with a "band-aid." Maybe some vacuum tests are in order and running the catch can for a couple hundred miles to see how much she scavenges?
 
#21 · (Edited)
I believe it doesn't matter if the filler cap is on the passenger or driver side as long as the other side has the PCV valve. It's just more normal to have the filler on the driver and PCV on the passenger but either way will work. The PCV needs to connect to the spacer underneath the carb. If there's a catch can in the middle of it, your choice to remove it or keep it. From under the air cleaner, it needs to go to the filler cap or block it off at the air cleaner if you get a cap with an air filter on top of it.

BTW, your pictures are tiny! Are you uploading from a phone? Usually tiny when you upload from phone.
 
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