Stupid PCV question

[FORMONTOYA]

I've gone through 2 OEM PCV (read boost leak) valves in 1500 miles since the car came off jack stands December 05. I'm tired of buying and replacing them even though they are not that expensive. I was going to pull the nipple out of the intake and put a 1/8 BSPT plug in that location and use the nipple from the intake and replace the PCV valve, however, the nipple is a press-in fit so that's out of the question. I just capped off the nipple and used the PCV valve as my nipple to "T" into the vent line going to the intake before a G-2 gas filter (catch can).

My question is why do I have to hog out the PCV valve internals? There shouldn't be a differential pressure type of thing going on, therefore the PCV valve should remain open, shouldn't it?

Below is a half-a$$ drawing of what I propose and if someone can give me a legitimate reason why it should be hogged out, I'll just order a nipple for it.

 

[oldman]

Thanks Bruce ... the cover is slightly damaged and removed long time back

Well, get another, would you run your car without a valve cover? At least cover it up every time you open the hood.

 

[4wd-Eclipse]

Well, get another, would you run your car without a valve cover? At least cover it up every time you open the hood.

I'll get a new one ASAP

 

[Calan]

Hell... where is..... everything?

Definitely looks nice

 

[Calan]

I have the large can mounted up nicely. I removed the (non-functioning) draincock in the bottom (same as the one on the mini version) and replaced it with a SS press lock tube fitting. A tube then goes from there to a remote brass draincock mounted down on the sub-frame, below and just in front of the clutch line bracket.

The hole in the bottom of the bowl is just slightly less than 7/16, which is the perfect size for a 1/4 NPT tap... should anyone else need to replumb these things slightly . Just be sure to cut the threads slowly and carefully to avoid cracking the bowl.

Now we'll see if I create another oil geiser on the way to work in the morning

 

[Calan]

BTW - The bowls are made of polycarbonate plastic. When I read the fine print that came with these for some reason, under the heading "MATERIALS THAT ATTACK POLYCARBONATE PLASTIC (PARTIAL LISTING)" I found:

1. Gasoline
2. Methyl Alcohol
3. Ethylene Glycol
4. Brake Fluids
5. Refrigerants (Freon)

etc. etc.

I'm sure glad there isn't any of this stuff floating around in my engine bay!

 

[nightspeed87]

I kind of ghetto rigged my pcv set up because I have a cyclone intake mani and it has no intake mani port available for me to use for pcv on my cyclone. I currently have a gatorade bottle with a long pcv line and long valve cover breather vent line going into the top of the gatorade bottle ( two holes drilled in top of cap for both v/c, and pcv lines, its sealed, no unmetered air getting in ) and one line going into the side of the bottle going to the intake arm port... Kind of stupid but theoretically I dont see how its much different from a real catch can. I will eventually do this the right way and get a nice chrome shiney catch can but in the mean time will just bear with what I rigged up..

 

[Calan]

intake arm port ?

I could be wrong here (it happened once before a long time ago ) but...

If I'm reading that correctly, you aren't relieving crankcase pressure during vac conditons. You need the two air "circuits" isolated; the PCV vents CC pressure during vacuum, and the v/c when under boost. By having them tied together, I believe you are neutralizing one or both.

Bruce?

 

[romeen]

OK Bruce, Craig.....enough talk about who has the bigger "catch can." You guys should take your Geritol and go to bed. Matlock is on early tomorrow.

you must be a better blower than I.

I said stop with talk already! (Sorry Bruce, but you got to admit...you left the door wide open on that one).

And just so I can say that I actually said something pertinent to the thread in this post the plastic check valve is still holding strong. Pressurized system to 25 psi the other day and not the tiniest bit of air got past it.

 

[Calan]

the plastic check valve is still holding strong. Pressurized system to 25 psi the other day and not the tiniest bit of air got past it.

Big whoop.. I pressurized my stock PCV valve to 27 psi tonight without a leak..

Actually, it was about 23... still pretty good for a stock PCV valve though. I can live with that.

And I'm all out of Geritol... can I have some of yours?

 

[nightspeed87]

intake arm port ?

I could be wrong here (it happened once before a long time ago ) but...

If I'm reading that correctly, you aren't relieving crankcase pressure during vac conditons. You need the two air "circuits" isolated; the PCV vents CC pressure during vacuum, and the v/c when under boost. By having them tied together, I believe you are neutralizing one or both.

Bruce?

Hm.. Lets see here, the pcv works only under vacuum, and the v/c under all strong vacuum situations which Ive already concluded that much. The intake arm port should have constant vacuum or at least a strong vacuum under boost and I suppose even stronger "suction" the more boost that is ran. ( somewhat of a question)
But seems your saying that the pcv isnt suppose to be under any suction during boost
since the pcv wouldve regularly have been closed from positive pressure, therefore your saying it could be under a negative effect from both pcv and v/c ports being to the intake arm.... I mean it sort of makes sense, but how I have it set up didnt think it would suck enough that it would nuetralize anything, i mean its just one hose from the intake arm sucking out the pcv and v/c hoses crankcase that fills the gatorade bottle. can any one elaborate on that?

 

[95CarbonEclipse]

Big whoop.. I pressurized my stock PCV valve to 27 psi tonight without a leak..

Actually, it was about 23... still pretty good for a stock PCV valve though. I can live with that.

And I'm all out of Geritol... can I have some of yours?

...but for how long is that going to last??? The whole point of having the check valve isn't because the OEM PCV valves don't work. It's because they don't work for very long before needing to be changed. Typically they go bad before your oil needs changing.

 

[95CarbonEclipse]

intake arm port ?

I could be wrong here (it happened once before a long time ago ) but...

If I'm reading that correctly, you aren't relieving crankcase pressure during vac conditons. You need the two air "circuits" isolated; the PCV vents CC pressure during vacuum, and the v/c when under boost. By having them tied together, I believe you are neutralizing one or both.

Bruce?

No... that should work, as long as both ports are connected to the intake pipe. It's not neccesarily correct, but by eliminating the PCV valve to IM connection you won't ever have to worry about boosting the crank case. And during idle (the only time the PCV is allowing air through it) the turbo should generate enough vacuum (especially when connected to 2 sources) to effectively evacuate any CC vapors.

 

[oldman]

Hm.. Lets see here, the pcv works only under vacuum, and the v/c under all strong vacuum situations which Ive already concluded that much. The intake arm port should have constant vacuum or at least a strong vacuum under boost and I suppose even stronger "suction" the more boost that is ran. ( somewhat of a question)
But seems your saying that the pcv isnt suppose to be under any suction during boost
since the pcv wouldve regularly have been closed from positive pressure, therefore your saying it could be under a negative effect from both pcv and v/c ports being to the intake arm.... I mean it sort of makes sense, but how I have it set up didnt think it would suck enough that it would nuetralize anything, i mean its just one hose from the intake arm sucking out the pcv and v/c hoses crankcase that fills the gatorade bottle. can any one elaborate on that?

No... that should work, as long as both ports are connected to the intake pipe. It's not neccesarily correct, but by eliminating the PCV valve to IM connection you won't ever have to worry about boosting the crank case. And during idle (the only time the PCV is allowing air through it) the turbo should generate enough vacuum (especially when connected to 2 sources) to effectively evacuate any CC vapors.

You will not see consistent vacuum in the intake PIPE, only when the turbo is spooling will you see vacuum. The problem with your setup is just that, lack of vacuum unless you're boosting, imagine what happens to all the blow by/contaminates while you're stuck in traffic for 30 mins.

 

[95CarbonEclipse]

^^^ But, where does the air come from that the IM is sucking in during idle? I was thinking it'd be the same place that ALL the air comes from... the air filter/intake pipe. Am I wrong??

 

[oldman]

^^^ But, where does the air come from that the IM is sucking in during idle? I was thinking it'd be the same place that ALL the air comes from... the air filter/intake pipe. Am I wrong??

Yes but the biggest restriction is the throttle plate, you simply can not out flow your k&n while the throttle plate is closed or slightly open.

 

[nightspeed87]

^^^ But, where does the air come from that the IM is sucking in during idle? I was thinking it'd be the same place that ALL the air comes from... the air filter/intake pipe. Am I wrong??

No I see oldmans point, the vacuum is no were near as strong as it is inside the manifold right before the cylinders...

You will not see consistent vacuum in the intake PIPE, only when the turbo is spooling will you see vacuum. The problem with your setup is just that, lack of vacuum unless you're boosting, imagine what happens to all the blow by/contaminates while you're stuck in traffic for 30 mins.

Yea i was thinking that, but its actually better than it was, before it was two long lines ( one from the v/c and one from the pcv ) hanging down by the dp at the back of the engine towards the ground, which it was like that since the original owner of the car... On my cyclone theres no pcv port for me to use so Im stuck without having it working correctly during idle situations due to that unless I get a new manifold.
Luckily I dont do very much city/ traffic driving in this car. But thats not a justification.

One last thought, could an improper pcv set up ( like mines ) cause the car to try to die when coming to a stop.
( Rpms falling to low like the engine isnt catching itself in time.) Only boost leak I have is a very minor one at the tb so its not like a major vacuum leak , and I havent replaced the tps yet which is my main thought on why its doing that.
It was always doing that ever since I had the car and Ive gotten used to putting it in nuetral and letting engine rev down by itself before stopping.

( BTW I have a act 12lb flywheel if that matters.)

 

[95CarbonEclipse]

No I see oldmans point, the vacuum is no were near as strong as it is inside the manifold right before the cylinders...

Well thank God I still have mine hooked up in an OEM fashion.

I was wondering though (only because I still get the occasional puff of blue smoke during shifts) if using an OEM PCV valve in conjunction with a check valve has any benefit at all compared to an Autozone PCV valve used w/ a check valve?

 

[Calan]

No I see oldmans point...

Damn it.. it was my point originally!

J/king... Bruce has probably forgotten more about these cars than most of us will ever know.

 

[Calan]

...but for how long is that going to last??? The whole point of having the check valve isn't because the OEM PCV valves don't work. It's because they don't work for very long before needing to be changed. Typically they go bad before your oil needs changing.

I'm just giving Romeen a hard time... I've got a couple check valves on order

 

[Dream On]

No I see oldmans point, the vacuum is no were near as strong as it is inside the manifold right before the cylinders...



Yea i was thinking that, but its actually better than it was, before it was two long lines ( one from the v/c and one from the pcv ) hanging down by the dp at the back of the engine towards the ground, which it was like that since the original owner of the car... On my cyclone theres no pcv port for me to use so Im stuck without having it working correctly during idle situations due to that unless I get a new manifold.
Luckily I dont do very much city/ traffic driving in this car. But thats not a justification.

One last thought, could an improper pcv set up ( like mines ) cause the car to try to die when coming to a stop.
( Rpms falling to low like the engine isnt catching itself in time.) Only boost leak I have is a very minor one at the tb so its not like a major vacuum leak , and I havent replaced the tps yet which is my main thought on why its doing that.
It was always doing that ever since I had the car and Ive gotten used to putting it in nuetral and letting engine rev down by itself before stopping.

( BTW I have a act 12lb flywheel if that matters.)

You realize you could just drill and tap a barbed fitting into your IM right? You don't need to get another manifold, just fix yours. I'm not sure if you could remove the top part of the cyclone with the bottom part bolted on the car, but if so, it could be done pretty easily then I'd imagine. As for the dying, when did it start? My 8 lb fidanza never did that when the car was fairly stock. I don't know if it would be enough to cause it to die, but I'm sure you're losing metered some air if you just drilled into the gatorade cap and stuck some rubber lines in.

 

[AWDstylez]

Here's a suggestion for those of you more motivated than I: Put together about 5 options for *valid* DSM breather/PCV systems (with catch can, without, with nice check valve, with cheap-o, etc.) and start selling the kits on e-bay. Sending me a few bucks in proceeds would be appreciated .

Autozone sells all 5 options and more. It's vaccum hose cut to length, you have the option to buy as much as you want and dump it to atmosphere any place you choose. That makes the options unlimited. It also happens to be dirt cheap, extremely simple, guarantees no boost leaking into the crankcase and no oil/blowby in the intake air. Can't beat that with a stick.

 

[romeen]

Autozone sells all 5 options and more. It's vaccum hose cut to length, you have the option to buy as much as you want and dump it to atmosphere any place you choose. That makes the options unlimited. It also happens to be dirt cheap, extremely simple, guarantees no boost leaking into the crankcase and no oil/blowby in the intake air. Can't beat that with a stick.

I copied this post from a previous thread:

... if the hose is long enough to reach the bottom of the car then what you have setup is basically a road draft tube which is what all cars used to ventilate the crankcase before the advent of the PCV system (it's at least better than just a filter on the VC breather). The idea being that the airflow across the end of the tube while the car is in motion would create a little vacuum thus pulling blow by out of the crankcase. This does work to an extent but the question should be is it preferable or better than the stock configuration?

In my opinion it wont be as effective as a connection to the intake pipe in a TURBOCHARGED car. Although I don't know what kind of velocities the incoming air reaches when under boost I would be willing to bet that it is considerably more than any speed that your car will typically see while driving. More velocity=more vacuum effect. Of course the main downside to this is the oily buildup (which can be nearly negated with a catch can) as well as some contamination of the air charge leading to slightly less efficient combustion (probably not enough to make a significant difference unless you are racing professionally). The ideal system is of course a seperate vacuum pump but cost, space, added complexity and legality makes this not very practical for a DD.

As Bruce mentioned removing blow by gases which can get absorbed into the oil and form acids and other corrosive substances which break down the oil is the most important function. Not adequately removing these leads to a vicious cycle. The more the oil breaks down the more cylinder wall scouring you get. The more cylinder wall erosion the more blow by you get and on and on.

I can tell some personal experiences and you can draw your own conclusion. Over the years I have had:

1) Just a breather filter on the VC
2) Filter at the end of a hose
3) PCV disabled with both VC fittings leading to a vented catch can (RRE method)
4) And for the past year the stock configuration with the addition of sealed catch can and check valve.

Over the years of doing the first three methods my oil would come out looking very dark, thin, and smelling really nasty. Since going back to the stock configuration my oil comes out looking quite clean with good lubricity remaining and not smelling like something that belongs in a military bio weapon or something. And I just use regular (petroleum) Valvoline 10-30....nothing fancy at all. Again, draw your own conclusions.

I am always open minded and willing to listen to any argument. Unfortunately there really isn't much hard data to prove one vs the other. So we have to rely on basic principles and common sense. The laws of physics would seem to favor the stock configuration for reasons discussed above.

If I read something favoring the PCV elimination argument that has some sound principles backing it up and makes more sense than the above argument I will be the first one to admit that I was wrong.

 

[nightspeed87]

You realize you could just drill and tap a barbed fitting into your IM right? You don't need to get another manifold, just fix yours. I'm not sure if you could remove the top part of the cyclone with the bottom part bolted on the car, but if so, it could be done pretty easily then I'd imagine. As for the dying, when did it start? My 8 lb fidanza never did that when the car was fairly stock. I don't know if it would be enough to cause it to die, but I'm sure you're losing metered some air if you just drilled into the gatorade cap and stuck some rubber lines in.

No its sealed, no unmetered air coming out or going in the bottle. ( Might sound crazy but some electric tape and black silicone were involved . )
And no this cars idle has been dropping since i had it. Just got used to it.
The flywheel was in there before I bought it, but on my gst I had a fidanza 9lb flywheel also and the revs would fall faster but not to were it wanted to cut off...
This thing can be sitting still and rev it up and it will fall down to like 400rpm by itself, and then go back up, despite me having it set at 900. its like it doesnt catch itself to good.
Any ideas as to why?

 

[DSMunknown]

I thought I had a possible solution to Jim's (and everyone else's) problem. For shits-n-giggles I bought a Lancer Evoution VIII PCV valve. I thought that perhaps the performance of these valves would somehow be superior to the our own OEM valves. Keeping post #16 in mind, I wasn't completely sure if the Lancer valve would perhaps flow more than the DSM valve. But since many of us "borrow" parts from the EVO family anyways, () I thought "Why not give it a shot?" Ordered the parts from a very trusted vendor, and revieved them a couple days ago.

Just as a reminder, here are the parts numbers:

• DSM - MD024719
• EVO - MD152772

Yeah, the Lancer Evo valve is about 18 bucks, compared to our 5-6 dollar valve (which may in fact be better designed). Not completely sure the design of it is even superior to the DSM valve. So here are a few photos I took. BTW, the EVO valve is on the left, and the DSM valve is on the right.

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I don't know how the Lancer Evo family is handling any and all issues with the PCV system, but if what Steve said has any sense (which it obviously does), I can't image the frustrations they must be going through.

Maybe I'll try out the Evo valve just for kicks. Perhaps Jim will also give it a whirl?

Before I forget, I did my best to measure the inside diameter of the valve splash shield on the DSM and then on the EVO. They both seemed very similar, if not the same size. According to my measurements, the DSM valve measures 5.05mm (approx.) and the EVO valve measures 5.25mm (approx.). However, regardless of my measurements, I think if there are any differences regarding the inside diameter, the difference is probably closer to 0.10mm.

It is also noteworthy to tell you that the thread pitch is the same on both valves; I tested both on an old cracked valve cover I had lying around. I also noticed when doing this quick test that the threading inside the valve cover goes well beyond the reach of the threading on the PCV valve. Perhaps when considering alternative aftermarket options this would be taken into consideration. Perhaps someone can find a long fitting that can act as a self-made splash guard, instead of mocking up another type of shield.

 

[DSMunknown]

Granted it doesn't take long to clean or replace one, but how long is it leaking before you find out about it? With it NOT holding back the boost PSI, it allows it into the valve cover area, where I don't want it, makes the turbo work harder because of the leak.

I'm betting it's a sinch, but what do you (or others) clean the PCV valve with? I just picked up a can of Gunk Engine Brite and figured that would do just fine. And I'm sure it will. Probably just need to fill up a glass with the stuff and put a couple PCVs in there and let them soak for about 15 minutes or so.

A comment I forgot to mention in my above post - I'm wondering if there are any differences in the design of the spring and/or ball (the spring being the focus here) with the EVO valve that may be of use to us. Again, Steve's post must be taken into careful consideration. But still, I wonder....