Oil Breather Cap
10-05-2010, 05:00 PM
#1
Mopar Fan
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Oil Breather Cap
Do these things need replacing? The Cordoba's is all oily inside and was thinking of getting a new one. Also if I do should I get one that is set up for the hose to go to the air cleaner like it is. Or an open element type?
10-06-2010, 02:24 AM
#3
Admin
Yes, they do need to be replaced from time to time. I've seen them be run with a hose back to the air cleaner (the way I've always done it), but there are ones out there that just act like a vent.
10-06-2010, 07:33 AM
#4
Mopar Lover
Tim, et al -
I may be showing a lack of understanding here, but ... On an engine with a PCV system, are the breather caps (typically on the opposite valve cover than the PVC valve) supposed to allow air into the crankcase or help to vent out excess pressure?
My understanding was that the PCV line was to suck crack case gases (from ring leakage, etc) back into the intake plenum for "re-combustion" and the breathers were there to allow air back into the crank case so you didn't create too much of a crank case vacuum. If there's a lot of oil fouling in the breathers on a PCV system, that might indicate a PCV problem.
Obviously without a PCV system, the breathers would act as an (inefficient) exit port.
72 - Anyway, yes breathers and PCV valves do need to be replaced.
Archer
I may be showing a lack of understanding here, but ... On an engine with a PCV system, are the breather caps (typically on the opposite valve cover than the PVC valve) supposed to allow air into the crankcase or help to vent out excess pressure?
My understanding was that the PCV line was to suck crack case gases (from ring leakage, etc) back into the intake plenum for "re-combustion" and the breathers were there to allow air back into the crank case so you didn't create too much of a crank case vacuum. If there's a lot of oil fouling in the breathers on a PCV system, that might indicate a PCV problem.
Obviously without a PCV system, the breathers would act as an (inefficient) exit port.
72 - Anyway, yes breathers and PCV valves do need to be replaced.
Archer
10-06-2010, 08:19 AM
#5
Admin
The oil breather cap usually goes back to the air filter so that the excess pressure can be burned threw the motor. At least that is how AMC did it on their motors.
10-06-2010, 10:36 AM
#6
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Tim, et al -
I may be showing a lack of understanding here, but ... On an engine with a PCV system, are the breather caps (typically on the opposite valve cover than the PVC valve) supposed to allow air into the crankcase or help to vent out excess pressure?
My understanding was that the PCV line was to suck crack case gases (from ring leakage, etc) back into the intake plenum for "re-combustion" and the breathers were there to allow air back into the crank case so you didn't create too much of a crank case vacuum. If there's a lot of oil fouling in the breathers on a PCV system, that might indicate a PCV problem.
Obviously without a PCV system, the breathers would act as an (inefficient) exit port.
72 - Anyway, yes breathers and PCV valves do need to be replaced.
Archer
I may be showing a lack of understanding here, but ... On an engine with a PCV system, are the breather caps (typically on the opposite valve cover than the PVC valve) supposed to allow air into the crankcase or help to vent out excess pressure?
My understanding was that the PCV line was to suck crack case gases (from ring leakage, etc) back into the intake plenum for "re-combustion" and the breathers were there to allow air back into the crank case so you didn't create too much of a crank case vacuum. If there's a lot of oil fouling in the breathers on a PCV system, that might indicate a PCV problem.
Obviously without a PCV system, the breathers would act as an (inefficient) exit port.
72 - Anyway, yes breathers and PCV valves do need to be replaced.
Archer
Last edited by Polaradude; 10-08-2010 at 01:07 PM.
10-06-2010, 11:46 AM
#7
Mopar Lover
Tim -
Sorry, not really familiar with AMC motors, did they use a separate PCV valve? Yes, a lot of factory breathers are hosed back to the air cleaner. Never quite sure if that was to suck air out or in. Most of the "rods" have stand alone breathers and that's what I'm more used to, using the above mechanism. At least that was I was taught a while back.
Archer
Sorry, not really familiar with AMC motors, did they use a separate PCV valve? Yes, a lot of factory breathers are hosed back to the air cleaner. Never quite sure if that was to suck air out or in. Most of the "rods" have stand alone breathers and that's what I'm more used to, using the above mechanism. At least that was I was taught a while back.
Archer
10-06-2010, 04:09 PM
#8
Mopar Lover
in the 60's (from what i know)california cars, or cars around that area got them standard
the pcv valve then went on the passenger side
10-06-2010, 07:34 PM
#9
Admin
I remember back in school that one of my mechanical teachers told us a story about when he was working in a garage. He had just done a complete tune up on a car (can't remember the make or model) but when he went to go drive it out, the car was running wrose than when it came in. He checked and double checked the timing, points, spark plugs gaps, carb jets, etc., etc., etc.. One of the older techs came over to him afterwards and asked if he had changed the PCV valve and he said yeah. The old tech told him to find the old one and put it back on. My teacher did that and the car ran properly again. Turned out, the parts department gave him the wrong PVC valve for the car.
My understanding (if my memory serves me right) is that the PCV valve helps to keep a certain pressure balance in the oil "area" (pan and passages). I think they act a lot like a radiator cap, if you have the wrong cap, the system will not work properly.
10-09-2010, 11:49 AM
#10
Mopar Lover
the more pressure will act as a reserve compression, when the piston comes down, the pressure will fight its movement, something that is un-wanted
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