PVC valve - i need help.

[moshem74]

hi.

1). does the pvc valve is taking the fresh air into the engine or out?

2). can i connect PVC valve of other kind of subaru if its fit? like impreza?

i have a new PVC valve of impreza , and i chacked and it's the same size, and i can connect it insted the old one that i have now.

3). i disconnected the lines that comes from the 2 head's of the engine(each side) and connect each line to an small open filter, now, i disconnect also the line of the PVC valve from the air cleaner box and i don't know what to connect to it in it's end, does a normal fuel filter will be good for that and,if the PVC valve takes the oil gass out, it will distroy the fuel filter no?

do i have to connect something in it's end? does the fuel filter will do dhe job? or i have to buy another small open air filter? can i leave it without nothing in it's end?

the car is subaru leone auto 1993.

thank you all for your fast answer.

moshe.

[EmmCeeBee]

Hey moshe, keep 'em coming I'm learning a lot by reading the answers to your questions.

 

I'll try this one:

 

1) Well, the PCV valve ("Positive Crankcase Ventilation") does suck air into the engine, but it's not exactly fresh air. It sucks gases out of the left side valve cover (driver's side in the US); fresh air is sucked into the right side valve cover (passenger side in the US), and the whole flow is right-to-left so that the crankcase is ventilated. The "fresh" air to the right side comes through a hose that's connected to the fresh air intake (either carburetor or fuel injected systems), so that it's guaranteed to be filtered. The PCV valve itself leads into the combustion path (below the throttle body) so that the engine gases can be burned. Result: cleaner emissions.

 

That's all there is to it. Occasionally you might get oil sucked into the left-side hose (1993 models should have a design that prevents this). Of course, after a few years the hoses get rock hard and plugged up with deposits. So it's a good idea to clean them or replace them. You can also soak the PCV valve in solvent, because it can get sticky and not open properly. A PCV valve should rattle when you shake it. There's more to it than that, though, the spring should let it open at exactly the right vacuum level. They're cheap, just replace it after a few years.

 

I believe you can disable the whole PCV system and not affect the running of the engine (I haven't done this....) But it certainly will affect the emissions, and is probably illegal in any area that has emission standards.

 

2) For the same reason (that it won't affect the running engine), I bet you can plug in any PCV that fits. But why? They're only a few dollars (in the US anyway). Most people on the board swear only by an OEM part for the PCV valve. You can do an internet search to see if the part numbers are the same for 1993 Leone and Impreza, but I bet they're not....

 

3) Cars before the 1970's just dumped crankcase gases to the atmosphere, so that's what your new setup is doing (if I understand your description right). Shouldn't give you any problems, except excessive emissions. Just plug the fitting for the hose in the "air cleaner box". DON'T connect any of the PCV hoses to the fuel filter.... Don't even think of it, I don't see how you could do that anyway. Don't leave the "air cleaner box" fitting open, or you'll have a huge vacuum leak and screw up the air flow metering.

 

Hope this helps.

 

edit: Oh, if you take all the PCV stuff off, you'll have to plug the hole where the PCV valve itself was mounted, too.

 

-- Mark

[MorganM]

On my EA82 I ran the 2 lines from the heads to a T fitting. Then ran the single line that was supposed to go to the PCV valve to an small breather filter. I removed the PCV valve from the intake manifold and replaced it with a solid bolt; making sure the threads were correct and that the bolt was not too long. The intake manifold is now sealed. The crank case now vents to the atmosphere through a filter. I did this so I'm not sucking foul, oily, gases into my intake manifold and combustion chambers.

[NorthWet]

On my EA82 I ran the 2 lines from the heads to a T fitting. Then ran the single line that was supposed to go to the PCV valve to an small breather filter. I removed the PCV valve from the intake manifold and replaced it with a solid bolt; making sure the threads were correct and that the bolt was not too long. The intake manifold is now sealed. The crank case now vents to the atmosphere through a filter. I did this so I'm not sucking foul, oily, gases into my intake manifold and combustion chambers.

If this is what you have done, you are running a small risk of having a crankcase explosion.

 

The pre-PVC (BTW, mid-60's not 70's) engines used a road-draft tube to created a partial vacuum to draw off blow-by gases from the inside of the engine. If all that you have is something that kind of filters any air moving in/out of the engine, then you have a potential for build up of explosive blow-by gases.

 

A road-draft tube is simple to build: Just a tube hanging down to the underside of the car, with the tip cut at an angle opening the tube towards the rear of the car.

 

IMHO though, it is a bad idea to eliminate the PVC system. The car was designed/tuned to run with it, and it really does no harm IF the oil is separated/filtered from the blow-by. Doing without it is worse pollution wise than running with your gas cap off. Plus blow-by gases stink horribly and because they are oily will cling to fabric (interiors, your clothing).

 

Just my 2 cents.

[MorganM]

If this is what you have done, you are running a small risk of having a crankcase explosion.

 

The pre-PVC (BTW, mid-60's not 70's) engines used a road-draft tube to created a partial vacuum to draw off blow-by gases from the inside of the engine. If all that you have is something that kind of filters any air moving in/out of the engine, then you have a potential for build up of explosive blow-by gases.

 

A road-draft tube is simple to build: Just a tube hanging down to the underside of the car, with the tip cut at an angle opening the tube towards the rear of the car.

 

IMHO though, it is a bad idea to eliminate the PVC system. The car was designed/tuned to run with it, and it really does no harm IF the oil is separated/filtered from the blow-by. Doing without it is worse pollution wise than running with your gas cap off. Plus blow-by gases stink horribly and because they are oily will cling to fabric (interiors, your clothing).

 

Just my 2 cents.

I'll post pics when it blows up :-p

 

I'm interested in this draft tube but not quite sure about it. I'll read it a few more times but elaobrate if you could please.

 

Thx

[NorthWet]

Which part do you want me to elaborate on... the *EXPLODING* part?!

 

I assume the design, so: Dumb simple device, don't try to think too complicated here. All it does is uses air passing by the end of the tube to suck the fumes out. It usually points down so gases go under the car instead of into vents, plus any oil also drips out. (:mr yuck!) The rearward side of the tube's end is cut away to enhance the sucking effect (think of fuel discharge tube in carb venturi... same thing).

 

My '58 Triumph had a road-draft tube, and after a hard drive we smelled like blow-by.

[moshem74]

hi

thank you all for your answers.

i chacked today, i took out the PVC valve, i clean it and it's working great, also i chacked the impreza PVC valve, and it's look the same but , with the impreza valve, it can move air in or out, my PVC just air in,out it cant go-just one way.

today i'm gone connect it back and also i'll use T connection to connect it with the left side line , and to an open small filter.

it's better to put the open small filter near the PVC valve or near the engine head? it's make any difrent?

 

thank you all.

moshe.

[archemitis]

on cars that have excessive blowby, pcv routing is a must. my ea81 will foul plugs, because its got enough blowby to force oil down the intake... every v8 ever hotrodded has crank breathers and i have never heard of an exploded crank due to pcv gasses...

egrs are for suckers too! =]