I just bought a couple of PCV valves one for my 03 tacoma (V6) and a ford focus (zetec) Well I was wondering how do I tell if the Valve is bad or needs replaced? I changed the one on the focus, I could not tell a difference between the new and old (I could blow through both sides of the valve and air passed through) the Tacoma though, I tried blowing through the OEM valve and it would only blow through one way, while the new replacement I could blow air through both directions. I am guessing the replacement valves (and the OEM Ford PCV) are defective because air should not pass both ways, correct?
how to check your PCV?
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You probably have carbon built up inside the old PCV valve. Some people try and clean them with gasoline......but it is best to install a new PCV valve.
Don't worry, I bought a new PCV valve for my wife's 98 Civic EX .....and I also noticed that air 'passes' both ways if I blow on the valve. No need to worry.
JHZR2
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Dont think that air should pass through both ways. Ill bet its not a perfect seal, but it ought to flow much better one way, per the design.
In my truck, I had a little engine shake at hot idle. I replaced the PCV Valve, and the idle smoothed perfectly.
It was an aftermarket part - maybe it wasnt the best quality, though it was a good deutsch one.
About 500 miles after replacement, the idle has began to get a little shaky again. Not as bad as before, but I can tell its coming back. Valve looks like new still... Maybe it gets a little oil in it with use.
Just a bit of info...
JMH
In my truck, I had a little engine shake at hot idle. I replaced the PCV Valve, and the idle smoothed perfectly.
It was an aftermarket part - maybe it wasnt the best quality, though it was a good deutsch one.
About 500 miles after replacement, the idle has began to get a little shaky again. Not as bad as before, but I can tell its coming back. Valve looks like new still... Maybe it gets a little oil in it with use.
Just a bit of info...
JMH
it's a spring loaded check valve. It seals one way (albeit not a perfect seal) and flows freely the other. Attach a hose (or not if you really like the taste) and blow. Should be free flowing one way and almost sealed the other. A *slight* leakage in the non-free-flowing direction is fine. Shake it, it should rattle easily as well.
or just replace it if in doubt they are awfully cheap.
or just replace it if in doubt they are awfully cheap.
the pcv for my expy is a motorcraft and they both blow both ways
looked at it and they have slits that let air thru
looked at it and they have slits that let air thru
my vic does not blow thru both ways...its the design of the system
Only for a check valve.
I believe most PCV valves will allow air to flow in only one direction. I don't know what cars have a different design than that or why it even matters.
I've had PCV valves that still rattled but the spring inside seemed to be so weak that I figured it would be best to replace it anyway, 50,000 miles and $10, seems it was about time in that car.
While this thread is up, on the other side of the valve cover, there is a tube about the same size as the PCV tube and goes into the air intake, that is part of the PCV system too, right? Is there anything that needs checking there?
While this thread is up, on the other side of the valve cover, there is a tube about the same size as the PCV tube and goes into the air intake, that is part of the PCV system too, right? Is there anything that needs checking there?
A simple RPM drop test well tell you if your PCV valve is working correctly on a variable control PCV valve.
There are also fixed orifice PCV valves on some older motors. Toyota for one used to use a fix orifice PCV system on some motors.
With the motor fully warmed up. Hook up a good tach. Set RPM to factory spec. Take note of the RPM. Pull the PCV valve and plug the end with your finger. Note RPM again. If the PCV valve is functioning correctly the RPM should slow down a MINIMUM of 50 RPM. If it does not replace the PCV valve with a OEM one.
Aftermarket ones are a crap shoot. As the OEM ones are a very calibrated and controlled leak.
Beware PCV valve hoses can also build up deposits on higher mileage motors. They should be replaced if they accumulate very much deposits. Because the inside diameter of the hose is also very important.
In general higher mileage motors will need to be replace more often because of increased blowby.
There are also fixed orifice PCV valves on some older motors. Toyota for one used to use a fix orifice PCV system on some motors.
With the motor fully warmed up. Hook up a good tach. Set RPM to factory spec. Take note of the RPM. Pull the PCV valve and plug the end with your finger. Note RPM again. If the PCV valve is functioning correctly the RPM should slow down a MINIMUM of 50 RPM. If it does not replace the PCV valve with a OEM one.
Aftermarket ones are a crap shoot. As the OEM ones are a very calibrated and controlled leak.
Beware PCV valve hoses can also build up deposits on higher mileage motors. They should be replaced if they accumulate very much deposits. Because the inside diameter of the hose is also very important.
In general higher mileage motors will need to be replace more often because of increased blowby.
It depends on how the PCV system was designed for the motor in question. Generally there will be more restriction one way than the other. A test like this does not tell you much IMO.
The Motorcraft the dealer sold me for the '92 Aerostar 3.0 V6 has the slits (or cuts) around the edge and blows both ways. It's part number Ev-228-B. The Motorcraft PCVs for my other Fords are not like that.
Lately I try to replace the PCV every 10,000 miles. When I do, the old one still shakes, but not as freely as the new one.
PCV valve replacement is probably a function of driving cycles. More short trips equals more sludge/condensation deposits in the PCV valve.
Regardless, for my GM 5.3L engine, I pay about 2 1/2 bucks for Purolator's at Advance Auto.
At that price, annual replacement is not a problem, especially since replacement is only about a 30 second job!
Regardless, for my GM 5.3L engine, I pay about 2 1/2 bucks for Purolator's at Advance Auto.
At that price, annual replacement is not a problem, especially since replacement is only about a 30 second job!
I don't really understand why PCV valve replacement is considered a regular maintenance item. I've never seen an owner's manual recommend PCV replacement at a certain time. If it sucks air, idle is good, and it functions as a check valve (if necessary for your vehicle), then it's fine. Sure, it's cheap. But there's a lot of other cheap things on your car you could constantly replace too.
I read somewhere that, at least for Hondas, a positive test for proper PCV valve function is to pinch the hose and listen to the PCV valve- if it 'clicks' when you pinch the hose, it's working OK.
I still think it's a good idea to replace them a minimum of once every two years but that's just my opinion. I think a lot of it depends on the engine itself.
I still think it's a good idea to replace them a minimum of once every two years but that's just my opinion. I think a lot of it depends on the engine itself.
How I check PCV vallves.
Remove old pcv valve and throw in trash van.. Place new PCV valve in its place.. all for less than the cost of a quart of quality motor oil.
Remove old pcv valve and throw in trash van.. Place new PCV valve in its place.. all for less than the cost of a quart of quality motor oil.
On both of my vehicles ('97 Mazda B2300 and '00 Honda Civic) the PCV valve is a royal pain to get to. Since Purolator replacements are something like $3, if I bother to remove it a new one goes back in its place.
I think I've removed and tossed out several perfectly good valves on the truck, but the Civic seems more prone to gumming. It started having a rough idle that went away when I replaced the PCV valve, and the one I took out looked pretty gooped up.
I think I've removed and tossed out several perfectly good valves on the truck, but the Civic seems more prone to gumming. It started having a rough idle that went away when I replaced the PCV valve, and the one I took out looked pretty gooped up.
Because it is a cheap part that if improperly working can cause many headaches. Such as fuel in the oil, sludge, and gaskets leaks. Many are also designed to prevent a crankcase flash fire in the event of a intake backfire. For best motor life it should be replaced before it goes bad.
According to Toyota information. During a normal compression stroke a small amount of gases in the combustion chamber escapes past the piston. Approximately 70% of these blowby gases are unburned fuel (HC) that can dilute and contaminate the engine oil, cause corrosion to critical parts, and contribute to sludge build up. At higher engine speeds, blowby gases increase crankcase pressure that can cause oil leakage from sealed engine surfaces.
The purpose of a PCV is to remove these harmful gases from the crankcase before damage occurs.
Never seen a test on flow rates on PCV so I can't really say. I can say OEM ones in some cases last much longer in my experience. This seems especially true of Japanese cars. I have had aftermarket ones start acting up in under a 1000 miles more than once. I no longer use aftermarket PCV valves. In my Toyota the aftermarket ones are not even the same design as the OEM. My Toyota OEM use a tapered steel valve vs a flat tin plate for the aftermarket valve to adjust the flow. The difference in price is only $2.99 for the aftermarket vs $5.99 for a OEM Toyota. Its a no brainier in my case.
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