I am having a hell of a time trying to remove the PCV valve on my 90 b12. Since the valve itself is down below the intake manifold, it makes it that much more difficult to remove with all the hoses and such in the way. I have tried spraying the valve with wd40 but to no avail. I doubt the PCV valve has ever been changed on the car as far as I know and it is clogged with gunk, as well as the hose that connects to the valve cover. Besides hesitation, what would a clogged PCV valve cause? Also, any advise what I could try and do to remove it, besides taking it to a garage???
I don't know how to help you. I replaced mine also and it is not easy getting to the thing. Once I got to it though, mine came right out, but not without me playing contortionist! I think I had to use a "breaker bar" to get it loosened, actually. As long as you've removed the hoses connected to it and you're using the right socket (you don't want to round it off!), try using different length extensions or maybe one (or two) of those u-joint adapters. The kind that lets you drive a socket around a bend.
If you're having hesitation problems, I'd look for other causes (timing/ignition/fuel-delivery), but changing a clogged PCV valve is always a good thing to do and it might help some with the hesitation.
This may sound like a really dumb question but does the lefty loosey righty tighty rule apply to the pcv valve? I know there are some exceptions and I would feel really stupid if I were turning the valve the wrong way. Also, do I have to worry about shearing the valve right off if it is truly stuck? That would pretty much ruin my car I'd imagine.
I believe it is the positive crankcase ventilation valve, it lets the crank case breath so that pressure doesn't build up inside of it. There's much more to its use I'm sure...
dschrier, try using a deep well socket with a 1/2 inch breaker bar. if that don't do it, use a pipe to go over the breaker bar as a cheater bar. remember, leverage is the key.
Someone correct me if I'm wrong here, but I think the only symptom of a faulty/plugged pcv valve is increased oil consumption. I doubt that replacing your clogged up pcv valve will cure your hesitation problem.
PCV - what does it stand for? Positive Crankcase Ventilation. Let's pick that apart a word at a time and see just what this little piece of hardware does. Let's
start with the word Crankcase. The crankcase of an internal combustion engine is that portion of the engine that contains the crankshaft (no duh), the
connecting rods, the under side of the pistons. It is also connected via passages in the casting of the engine block to the upper engine, the valve train, the
camshaft and the timing gears and chain. The most critical part of the above components regarding the PCV is the pistons. Fuel and air enter the combustion
chamber on the top side of the piston where the fuel burns and forces the piston down. That motion is converted into rotary motion of the crankshaft via the
connecting rods and the crankshaft. That is what drives your car.
I mentioned that the combustion takes place in the combustion chamber. Ideally all the combustion gases which are in the combustion chamber stay there
until they are exhausted via the tail pipe, however as engines get older (and even in brand new engines) some of the combustion gasses get past the sealing
hardware on the pistons, the piston rings. As the engines age, the clearances between the rings and the cylinder walls increases and more of the combustion
gasses escape into the crankcase. These combustion gasses contain acids and other harmful by-products of combustion which used to escape from the
crankcase via a breather tube which exited into the environment. All that garbage going into the atmosphere makes smog and other breathing problems in
our environment. In addition, the moisture in those gasses also caused sludge to build up in the engine, so the PCV system also helps reduce the sludge build
up. So the engineers decided to capture all that stuff from the crankcase and ventilate it in a way that it becomes less harmful. Notice I said less harmful, not
pristine. Notice also that we have covered the second word, Ventilation.
What's so positive about Positive Crankcase Ventilation?
It is called positive since there is a positive force that removes the combustion vapors from the crankcase. That force is vacuum - just like the vacuum that
sucks the dirt out of your rugs and furniture only this vacuum is derived from the engine, not from a Hoover. Vacuum derived from the engine is a rather
sensitive resource, that is you don't want to steal any vacuum from the intake manifold when the engine is idling. However, when the engine is running at
highway speed the engine can afford to allow a "vacuum leak" to occur via the PCV Valve. It is a metered flow of air, controlled by a needle valve inside the
PCV Valve. When the engine is at idle and vacuum is high the force of the vacuum overcomes the force of a spring inside the PCV Valve and it is closed down
to allow a flow of about three cubic feet per minute. When the throttle is opened and the intake manifold vacuum is reduced (closer to atmospheric) then the
spring in the PCV Valve forces the valve to open allowing up to six cubic feet per minute of flow to occur.
So, what goes wrong? First, the spring can become weak or break and the valve will not open at all. This results in no removal of engine vapors and a build up
of pressure in the crankcase. The air will actually flow backwards into the air cleaner. One symptom of this is oil in the air filter housing at the entrance of the
PCV tube. This can also occur if the Blow-By is too high. Second, the valve can get gummy and stick in the open position allowing too much flow at idle
conditions. This results in a rough idle or a stalling condition. In either case, just whip out the Visa card and spring for a new one! They only a few bucks.
A quick check to see if it is faulty is to shake it rather violently and see if the ball inside rattles - if it does then it is probably OK. Then with the engine running, put your
finger on the end of the valve. You should feel a strong vacuum. If you don't then the valve is clogged and/or the tube is leaking. Fix or replace as necessary.
Doesn't help with removal, but helps explain the function of and symptoms of a faulty PCV valve.
now i know i must change mine ... duh was thinking the sludge was cumming from bad head gasket (before i bought the engine)... now i know better !! thanks a lot !
__________________
Crazy !
Sentra Sport Coupe 87 Turbo
14.850@97.454mph
H&R Spring, 15psi, TMIC, 370cc, Nismo mount and pulley, Almasi tuned ecu...
definetly need to change man. ironically ive had a brand new one for about a year but bein as though i was use to seeing f/i motors all the time i thought i didnt have one. .......and knowing is half the battle, GIJOEEEEEEEEEEEEEE!
I have a 85 200sx, fuel injected, non-turbo. I cannot find the pcv valve. What parts and/or hoses do you have to take off to be able to see the pcv valve? If you have a picture or a diagram it would be most helpful.
More car is using oil, and I see liquid coming down from the number 1 and 2 plugs. What is the a symptom of?
The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.
AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.
Thats all it does.
Linear Mode
