Hello, first post. My question is about pcv systems, specifically why other than convenience is the air inlet usually located in the valve/rocker cover? It seems a better location for inlet air is into the crankcase to more easily sweep up blow-by gases.
pcv systems
- Thread starter jldcol
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Welcome!! I don't know.
The referenced article does support my theory that v engines that use this air inlet into one valve cover and drawn out through the other are better cleaned because the air must flow from one side of the engine down through oil drain holes across oil sump and up and out the other side.Whereas inline engines have the air in/out very close together, less than 2 feet apart usually and even with baffles the air will short circuit most of the engine and really only ventilate the valve cover volume.
My bad.
The purpose of the PCV system is not to flush the engine with air.
It primarily relieves crankcase pressure through the PCV valve, and recirculates the blowby gasses into the intake manifold. It operates on manifold vacuum, which is pretty high. Only on low blowby conditions does the inlet really have to supply any flow.
So if you need it, it will work fine even with the inlet and outlet on the same VC.
It primarily relieves crankcase pressure through the PCV valve, and recirculates the blowby gasses into the intake manifold. It operates on manifold vacuum, which is pretty high. Only on low blowby conditions does the inlet really have to supply any flow.
So if you need it, it will work fine even with the inlet and outlet on the same VC.
I would submit that there is alot of air flow thru the pcv system. Most sources i read say 1/4 to 1/3 of the air thru the engine at idle is through pcv system. By flush I mean to replace the high unburned HC's with less corrosive air. Suction requires flow. Blow by gases in an inline engine would have to get to the top of the engine via oil drain passages from the lower crankcase. Once up there the would have to get between the inlet and outlet to get caught up in the flow. pretty roundabout. Now if air were let into the lower crankcase then the flow would push these fumes up into the valve cover area and out. Definitely more direct.
In my engine it uses a Crank Case Breather into the Intake Throttle Body, and a PCV on the Valve cover also running to the Throttle Body. When idling my cars PCV is open and allowing gases to flow into the throttle body. When under-load the PCV is closed and the breather is venting all the pressure and gases into the throttle body itself. This is whats stated in my vehicles Technical Manual that I bought from the dealer.
If air from intake were routed to the crankcase, then under high load conditions the reverse PCV flow would pickup oil-laden crankcase vapor and pull it into the intake duct. You would lose a lot of oil. As it is there is still some oil in the vapors in the valve cover and the oil causes grime buildup in the IACV, throttle body and plate, and eventually requires cleaning,...at least on Hondas and probably others as well.
regards
regards
This is gonna sound STUPID, but. . . . I have been wondering for a while, and no one can give me a good answer.
My 04 LS has the 3.9L AJ-V8. Whenever I look to see if I can replace the PCV I allways get "you do not have one" Both Lincoln and Jaguar dealers told me this. And all the parts stores say it is not made for this motor.
So what the story. Is my PCV just non servicable?
My 04 LS has the 3.9L AJ-V8. Whenever I look to see if I can replace the PCV I allways get "you do not have one" Both Lincoln and Jaguar dealers told me this. And all the parts stores say it is not made for this motor.
So what the story. Is my PCV just non servicable?
Surely there is a part number for the pcv valve. Can you locate the valve on the engine? Is it in a hose or sort of built into the valve cover or similar part? If in a hose should be able to change easily enough. If it's in valve cover it may be part of the cover and thus need to repalce whole cover. If there is a part number for it should be able to order one.
Originally Posted By: rg200amp
This is gonna sound STUPID, but. . . . I have been wondering for a while, and no one can give me a good answer.
My 04 LS has the 3.9L AJ-V8. Whenever I look to see if I can replace the PCV I allways get "you do not have one" Both Lincoln and Jaguar dealers told me this. And all the parts stores say it is not made for this motor.
So what the story. Is my PCV just non servicable?
PCV may be built into the PCV hose. See Rockauto.com for your vehicle. PCV hose only is avialable at $18.95, which sounds like hose and PCV as a unit.
good luck
This is gonna sound STUPID, but. . . . I have been wondering for a while, and no one can give me a good answer.
My 04 LS has the 3.9L AJ-V8. Whenever I look to see if I can replace the PCV I allways get "you do not have one" Both Lincoln and Jaguar dealers told me this. And all the parts stores say it is not made for this motor.
So what the story. Is my PCV just non servicable?
PCV may be built into the PCV hose. See Rockauto.com for your vehicle. PCV hose only is avialable at $18.95, which sounds like hose and PCV as a unit.
good luck
Originally Posted By: rg200amp
This is gonna sound STUPID, but. . . . I have been wondering for a while, and no one can give me a good answer.
My 04 LS has the 3.9L AJ-V8. Whenever I look to see if I can replace the PCV I allways get "you do not have one" Both Lincoln and Jaguar dealers told me this. And all the parts stores say it is not made for this motor.
So what the story. Is my PCV just non servicable?
Some cars DO NOT use a normal PCV valve in the PCV system. There is still a valve of some sort, but it will usually be built in to an evap hose or something similiar. Not easily or cheaply replaced when compared to the regular PCV valve.
This is gonna sound STUPID, but. . . . I have been wondering for a while, and no one can give me a good answer.
My 04 LS has the 3.9L AJ-V8. Whenever I look to see if I can replace the PCV I allways get "you do not have one" Both Lincoln and Jaguar dealers told me this. And all the parts stores say it is not made for this motor.
So what the story. Is my PCV just non servicable?
Some cars DO NOT use a normal PCV valve in the PCV system. There is still a valve of some sort, but it will usually be built in to an evap hose or something similiar. Not easily or cheaply replaced when compared to the regular PCV valve.
There is air flow, of course. But that is no the intent. It does no good on it's own.
The changing pressure/vaccum in the crankcase area could affect the free-flow of oil from the valve area adversly. This way pressure is purged from all areas.
Also -as mentioned- outtake is intake at different speeds. Changing flow direction also have benefits against dirt trapping. (Reminds me filter systems of industrial vacuum cleaners.)
'72 Chrysler manual is quite concise about then-new PCV.
Also -as mentioned- outtake is intake at different speeds. Changing flow direction also have benefits against dirt trapping. (Reminds me filter systems of industrial vacuum cleaners.)
'72 Chrysler manual is quite concise about then-new PCV.
Originally Posted By: rg200amp
This is gonna sound STUPID, but. . . . I have been wondering for a while, and no one can give me a good answer.
My 04 LS has the 3.9L AJ-V8. Whenever I look to see if I can replace the PCV I allways get "you do not have one" Both Lincoln and Jaguar dealers told me this. And all the parts stores say it is not made for this motor.
So what the story. Is my PCV just non servicable?
You may have a heated PCV, and it may be located before the throttle body. It won't be apparent, either. My recommendation is to follow any vacuum lines/tubes from the valve covers. If you find that one goes to the throttle body with some coolant hoses on it, then you have a heated PCV.
This is gonna sound STUPID, but. . . . I have been wondering for a while, and no one can give me a good answer.
My 04 LS has the 3.9L AJ-V8. Whenever I look to see if I can replace the PCV I allways get "you do not have one" Both Lincoln and Jaguar dealers told me this. And all the parts stores say it is not made for this motor.
So what the story. Is my PCV just non servicable?
You may have a heated PCV, and it may be located before the throttle body. It won't be apparent, either. My recommendation is to follow any vacuum lines/tubes from the valve covers. If you find that one goes to the throttle body with some coolant hoses on it, then you have a heated PCV.
or- it may be a fixed opening as mentioned in the article
Steve
Steve
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