How common is it for a PCV valve to be clogged on older car?

[aacaac]

ie 240sx. Want are the consequences?

[GSXRJJordan]

I've run into clogged PCV's on a couple SRs and KAs I've had - usually I notice that even though there's no boost/vacuum leaks, the car still doesn't come down to idle correctly, or has a slightly rocky idle, even after cleaning out the IACV. Replace the PCV and/or 1-way check valve, and you're golden.

I find that turbo cars have more of a problem with clogged PCV's, probably because there's more oil blowing through the piping/manifold.

[socal_kouki]

I don't think anything bad happens if it's stuck closed. Stuck open is a little more serious.. It can cause failures over time and your car wont run as well while the problem persists.

[aacaac]

I've run into clogged PCV's on a couple SRs and KAs I've had - usually I notice that even though there's no boost/vacuum leaks, the car still doesn't come down to idle correctly, or has a slightly rocky idle, even after cleaning out the IACV. Replace the PCV and/or 1-way check valve, and you're golden.

I find that turbo cars have more of a problem with clogged PCV's, probably because there's more oil blowing through the piping/manifold.

Good stuff. I guess I will have to move my alternator out of the way. Hope I dont have to take alt all the way out. Hard time shoving it back in with nothing else removed.

[Drftr915]

Mine is stuck closed or something, all i know is, is that my car dies when i decellerate and put it in neutral have to rev it up a little lightly to keep it alive. HELP!

[GSXRJJordan]

yup stuck open, creating a vacuum leak - replace it (and the check valve on the vac line to the brake booster) and it'll be golden.

[Bigsyke]

I don't think anything bad happens if it's stuck closed. Stuck open is a little more serious.. It can cause failures over time and your car wont run as well while the problem persists.

Wrong, do a little more research, the PCV is vital to engine longevity and operation. Besides windage in the crankcase, oil/fuel vapors need to be evacuated durring startup and shutdown. If the valve is stuck closed they cling to the walls of the crankcase and wash down to your oil. Also more importantly is the routing of your pcv. you want vacuum in the crankcase to also evac the vapors and pressure. The pressure can still work its way out via the valve cover, however then the fuel vapors will contaminate the oil. When the valve is open, and the crank case is in vacuum, the valve cover will suck in air via the intake tract. Durring WOT and high load usually the intake will extract the pressure from the valve cover.

You can easily blow out gaskets and seals with a clogged PCV valve. It is VERY important to make sure you change it every other oil change esp if your car is in colder climates because I have seen the pcv clog easier when the car is idled for longer periods and also durring cold startups because of the increased fuel. Usually the PCV valve getting clogged looks like butter.

Good stuff. I guess I will have to move my alternator out of the way. Hope I dont have to take alt all the way out. Hard time shoving it back in with nothing else removed.

Remove the alternator, its like 6 bolts and should only take about 5 minutes. Also remove the oil filter.

Mine is stuck closed or something, all i know is, is that my car dies when i decellerate and put it in neutral have to rev it up a little lightly to keep it alive. HELP!

yup stuck open, creating a vacuum leak - replace it (and the check valve on the vac line to the brake booster) and it'll be golden.


Doesnt your IACV compensate for this? You can crimp your PCV valve on just about any car and it usually doesnt die as far as I remember correctly, it may stumble, but there is enough vac sources to keep it running aka IACV/EGR

[GSXRJJordan]

Doesnt your IACV compensate for this? You can crimp your PCV valve on just about any car and it usually doesnt die as far as I remember correctly, it may stumble, but there is enough vac sources to keep it running aka IACV/EGR

IACV can compensate for the PCV, but not the 1-way check valve. My guess is that usually, PCV gets stuck and check valve starts having to do the job of both, then dies out too. Then you start having idle problems, which are magnified when you run a BOV to atmo. :angel:

You really replace your PCV every 2 oil changes? :coolugh:

[sidewayz240]

Replace PCV valve every two oil changes?!?! Wow, I'd like to see your list of things you replace every two oil changes if thats on it.

[S14DB]

As long as you keep the pcv intake on the VC behind the maf you shouldn't have a vac problem.

Like said before a stuck PCV is ether going to blow oil into your intake or rust out your block from the inside out as the contaminates burn off.

I would inspect it every 15k(5 oil changes) and replace it every 30K(10oc's). Sort of like when you check your plugs and gear oil. Just remove it and shake it. It should rattle back and forth. Air should only flow from the block to the intake manifold and it should seal if air is put on intake side. Replace it if it is gummed up.

[steve shadows]

PCVs are extremely cheap and you can get one for replacement on SR anywhere.

Make sure you are running appropriate crank and engine evac systems (ie vacuum lines from the head and bottom end back into the catch can and then back into vacuum in front of the turbo).

Especially important on more tired bottom ends (plus you will pick up about 20-40 hp from this)

[aacaac]

IACV can compensate for the PCV, but not the 1-way check valve. My guess is that usually, PCV gets stuck and check valve starts having to do the job of both, then dies out too. Then you start having idle problems, which are magnified when you run a BOV to atmo. :angel:

You really replace your PCV every 2 oil changes? :coolugh:

Good discussion, everybody. Which check valve are you referring to in the above comment?

Stupid question but what causes my idle to plummet upon decelleration? I assume decelleration deprives the iacv of air but what is supposed to compensate? Is it just a matter of the idle adjustment valve being too tight setting a low floor for the idle? Is the aac valve supposed to act as a check valve . My aac valve definitely doesnt idle up or anything.

[Bigsyke]

on my civic every oil change. 3 buck is nothing when u drop 50 on some amsoil. I buy them in bulk OEM ONLY ppl! after 8 years and hundreds of pcv valves THERE IS A DIFFERENCE a big fucking difference...even if its just a check valve. the fram ones clogg in a week. oem has always lasted and idles perfectly. on the civic it took 30 seconds to change. s14 not so much, but I would like my oil to last...