TOPIC: Modification of the PCV System

I did this about a year ago on my '09 2.4L Toyo Camry...

The engine setup made it fairly easy. The PCV valve is on back of valve cover, closest to windshield; the intake manifold inlet is just 6-8'' below the valve cover. The OEM setup has a 6-8'' hose with a 3/8'' id at the PCV end and 1/2'' id at intake-manifold inlet.

I removed the OEM 6-8'' 'pcv hose' connecting them completely.

I capped off the 1/2'' id inlet on the intake-manifold (the sucking end) & used a 2'' length piece of rubber/fuel-line hose (3/8'' id) and old extra 1/4'' socket-nut that I lodged into 1 end of the hose to make the cap which has not failed me. It's air-tight and easy to remove for carb-clean injection treatment.

As for the PCV-valve end, (the end that is ejecting the crankcase vapors), I've experimented w/ a few different setups/location, upstream of throttle body, to vent the PCV crankcase vapors. Right now it vents through a hose from pcv valve into one of the air-intake resonators which connects to the main air-intake tube about 3-4'' upstream of throttle body.

Also, I drilled out the washer-ball/check-valve mechanism of the PCV valve. I had too many issues w/ pcv valves clogging and getting stuck within 1-200 miles.

not sure if this helps anyone; just thought I'd share my end of the stick.

PS the camry now has just over 350,000 miles; pcv reroute was done ~290,000 & it seemed to fix all oil-burning issues it had prior (along w/ liqui-moly treatment, wd40 injection & crankcase-cleanings (w/ yes, wd40!)

Claudio,

Would you mind editing your post (ABOVE) and re-attaching the picture?

Thanks!

Ron

This is something all California residents will want to pay attention to, as well as all you Gadgetmen out there!

The MAIN purpose of capping off the vacuum source is to STOP THE FLOW through the engine. This is done most quickly by applying a vacuum cap, but if CARB (California Air Resources Board) sees that cap, they're going to fail you!

So (and this works with ALL engines so equipped) you may simply remove the PCV valve, clean it, and fill it up with our OLDEST and most TRUSTED friend, JB-Kwik!

Claudio, this also applies to engines where the PCV system is self-contained, as in the newest Hondas et al.

I'm editing the original post next to include VITAL information as to WHY the PCV system should be capped on EVERY engine that has one!!!

So go back to the first post in this thread and read it!

Just a hint, boys and girls.

Just a hint...

Ron

I recommend people to simply use the CHEAPEST plugs they can find for their engine, as increasing the gap will force the system to deliver far more energy to the air/fuel mi8xture than any of those fancy, $10 or $20 plugs will!

And you won't have to worry about your posts showing up after three have been approved. This was done to stop the SPAMMERS, and it worked!

You won't find any Russian Babes here, or sexy, hungry Pilippino sex machines, either!



Ron

Hey Ron I put the attachments back on. Check them out. I will put a picture of the capped ends in about a hour.

Hi Claudio, to make it simple, the ONLY end you want to cap-off is the one that's sucking air IN.

Hose can be left hanging from PCV-valve or removed entirely. Generally this does not matter. And generally this is all you need to do..

If you cap-off the end where vapors are coming OUT (usually where the PCV-valve is) it will likely cause slight decrease in performance, hotter running temp and oil consumption since you're merely blocking off an exit for the heat/exhaust.
RON'S NOTE: There is no risk of losing power at this point. But it will violate EPA mandates of routing blow-by gases into the intake, as it will allow these caustic vapors into the atmosphere.

Now, Ron has said (correct me if I'm wrong Ron) that on most vehicles you can just leave the PCV valve open to vent into atmosphere. And if that works for you, hurray! Wish my setup was that simple...
RON'S NOTE: The PCV is a valve which is "Normally Closed" and requires force to open. No vapors will issue here.

However, on my '09 2.4 Camry, I cannot do this because first of all the car does not like PCV valves. I've gone through several and the one-way pressure mechanism of the PCV-valve (the inside ball-washer that you're supposed to hear move when you shake it) always gets stuck after a hundred or so miles. So I drilled out the check-valve mechanism inside the PCV-valve to make it completely hollow.

With the pcv-valve completely hollow, there is more venting, and leaving it out by itself creates too much vapor under the hood & travel through cabin air-vents and the smell is not so great, albeit probably not good to breathe...

So, I just connected a 3/8'' id hose to the hollow-pcv valve and the other hose end to air-intake (via drilled-hole & barbed fitting into plastic resonator before throttle body, after MAF). This way all of it vents properly, but under much lower vacuum than the intake-manifold (now capped-off). It's the high-vacuum of the intake-manifold shooting this into the air-mix/pistons/rings at high-temp each round maintaining the perfect condition for blow-by that ultimately kills your engine...
RON'S NOTE: All that was really necessary was filling the valve itself with JB-Kwik. That being said, you did exactly right in connecting the hollowed valve to the intake. Further, you grasp the system VERY well! The below atmospheric pressure will help further draw the vapors out of the crankcase. Good work! Great Sharing!

Hey Ron, when I heard of this mod my first reaction was that I may do more harm than good to my engine. So I watched some YT videos on what the purpose of the PCV system is. Then I got even more nervous about doing this modification.

One thing I'm not clear on: If the purpose of the PCV valve is to prevent pressure from building up inside the crankcase, then what happens if there is pressure in the crankcase? Won't it blow out seals and gaskets?

If you have the groove, I understand that combustion is more efficient and you're less likely to have pressure build up in the crankcase. But I don't want to turn my crankcase into a pressure cooker and blow out the seals.

If i'm understanding this mod correctly, we cap or plug the vacuum side of the PCV system, but leave PCV valve in place so that if pressure builds up it would be vented through the PCV valve into the engine bay.

I'd appreciate some clarification for those of us not as familiar with how our engines work. Is putting a cap on the PCV the same as sealing completely as a JBKwik plug?

Thanks!

You're concern is very common as most mechanics haven't got a complete understanding of the system and how it works.

Go back to the original post in this message thread and read them all. You'll see this whole fear thing about blowing seals is just fear based on propagation of mis-information that keeps people from messing with this system.

And what's the worst case scenario? You lose a little oil and put in a new PCV valve (or reconnect the hose if you used a vac cap)

And yes. Plugging the PCV has the same effect as putting on a vac cap as the goal of stopping the flow through that system to STOP. It's just KILLING your oil, increasing waste (pollution) and dropping your fuel efficiency.

Try it, Rudy.

You'll see.

Then, come back here and post a follow-up message!!!

Ron

Claudio, from the 2 pics- the lower cap is the PCV valve, the upper one is the one on the vacuum nipple. Leave the upper one as is, take the cap off the lower one. Ron and others like to just leave it open, or maybe leave the hose on the PCV valve, and just leave the hose end open.

What I prefer, like Wes spoke of here- is take the hose that's on the PCV valve, and connect it in some way to the incoming air stream. Sometimes it's easy to tee the PCV hose into the crankcase breather hose. Or to add a hose nipple to the main air inlet duct and attach the PCV hose there. Do it as you think best- and you could post pics of the result if ya like!

Tracy G

Yo Rudy--at the risk of muddling things up with my own explanation of the PCV system...I'll have yet another go at it.

The intent of the PCV valve and crankcase ventilation system is to provide a way for crankcase vapor to escape the crankcase, and prevent pressure buildup. And do it in a way that prevents the crankcase fumes from escaping to the atmosphere.

Problem is- this system also will suck in oil vapors and oil mist INTO the intake manifold. Fouling EVERYTHING from the PCV valve itself- all the way thru the intake tract, combustion chambers, exhaust system, cat. converters, all the way to the tailpipe tip. Long-term, this guarantees a shorter engine and vehicle life.

PLUS by using intake manifold vacuum to "power" this setup- it robs the engine of much of the critical pressure drop or Vacuum that's needed to vaporize the fuel.

WE reverse these bad things.

Once one understands how the PCV and crankcase vent. system works, the Light should turn on about all this.

You must understand FOR YOURSELF how this works--then you can think, understand, and then do this mod. Mechanics are taught to fix what "already is there". Not to do mods of this sort. But, the more enlightened of them should understand it as we do.

So, Please read, think, and try to visualize how this system works. IT really is simple.

Tracy G

REAL IMPORTANT UPDATE!

It has been brought to my attention that on some vehicles, especially with older engines with higher blow-by that excessive oil is being drawn into the throttle body, and may be causing the throttle plate to stick under normal operations.

Add to this that some systems have a MAF that is DOWNSTREAM from the breather hose connection and may experience oil vapor decay and possible destruction of the MAF sensor element (all it is is a heated piece of resistor wire or tiny resistor in most cases), it is important to be prepared to circumvent these issues.

If either of these systems are modified in this way, it will be strongly advised to install some type of vapor separation device such as a "Condensator" or "Catch-Can" as they're called in the breather hose line.

I'm just sayin....


IMPORTANT SOLUTION FOR BLOW_BY!!!
Now we have 100% Pure Snake Oil, we can fix excessive blow-by by adding less than a tablespoon of something to the crankcase.
Please visit 100% Pure SnakeOil, anti-friction for engines up to Big Rigs and read all about it.

Ron

I think the brilliant things about re-routing the PCV gasses to the upstream side of the throttle body are numerous:
1 - you're remaining compliant with generally widespread environmental laws
2 - you're making sure you're getting the most bang for your hydrocarbon buck
3 - the water vapour present in the blowby that's getting recycled actually HELPS combustion and keeping your intake tract clean; further, that vapour displaces some of the oxygen in the intake stream, making the 02 sensors more likely to see a rich condition and trim fuel delivery back
4 - because of the upstream relocation of the PCV vapour return, the manifold vacuum presented to it is variable with throttle plate angle; theoretically, at low throttle angles, the manifold vacuum is near peak and PCV recycling is low, while the reverse is true when the throttle plate is more open...yet the engine still gets its feed regardless of where the throttle is.

I can understand excessive oil fouling of the TB being a concern, but if you're going through THAT much oil, you probably have bigger problems (have you tried opening up the diameter of your hoses so that the gunk doesn't move through them as quickly but the lighter and hotter stuff does?), but once the engine adjusts to the flow and everything gets cleaned out, you'll likely be better off.

On my car, I had a BMW cyclone seperator on the PCV system, and after the first oil change, when I cleared all of the gunk out of the pipes and catch bottle, all that I found in the catch can subsequently was water that smelled like gasoline. At that point, I removed the seperator and the engine gets all the vapours now. Mileage is consistent or improving. I hope that remains the case as the weather turns cooler in a month or 2.