3100/3400 PCV Delete for Breather

[Michael Savage]

This was surprisingly easy to do and I was wondering if there is anything to watch for with this breather setup.

 

I removed:

1. The Throttle Body Bracket

2. The PCV Hose from Front VC to Evap

3. Intake to Rear VC

Next:

4. Unplugged EVAP and tucked the wire

Then Plugged:

Rear VC

5. Intake Under TB Bracket

6. Hole in Intake Hose

And Finally:

7. Add the Breather into the Front VC

 

So far the car has a better idle and seems to accelerate better. I'm sure somewhere there was a vacuum leak the setup is so flawed at that aspect. There's no easy way to prevent it from leaking air causing problems. So I deleted everything and so far it runs better and to me looks better and no check engine lights.

My friend bought it for his truck but he forgot to see if his valve was removable which it wasn't. So he gave it to me I plan on getting a red or black one to match better. Let me know what you guys think.

[Imp558]

PCV removes potentially corrosive blowby vapors and moisture from the crankcase so it's actually not a bad thing. When I was a kid there was a class in shop where we discussed the low pressure caused by vacuum through the PCV aiding with ring seal, but that may be a load of shit like most everything that teacher told us.

The breather does look cool though.

[Michael Savage]

It's a 50/50 honestly because the trade off is injecting oil and unmetered air into the engine. So either way it's bad but IDE rather have lower pressure than a consistent vacuum leak.

[RobertISaar]

PCV "air" is metered.

 

and it's only a vacuum leak if your valve is stuck open at idle or the tube that connects the valve to the intake isn't sealing.

[Michael Savage]

The intake tube to rear valve cover never seals on anyone's 3100/3400 that's the most common issue and unmetered air comes in because it's a vacuum leak. That's what I was saying by it's a consistent vacuum leak.

[RobertISaar]

unmetered implies unmeasured. the MAP sensor measures absolute pressure in the manifold, hence metered.

 

unfiltered air? maybe. stick the breather on that valve cover and if it seals against the grommet in the valve cover you solve that problem and can still have a functioning PCV system, which keeps all kinds of trash out of the oil in addition to lowering crankcase pressure.

 

with a breather on one valve cover and the other plugged, the only way for blowby/moisture/etc to escape the crankcase is via heat and blowby increasing pressure in the crankcase. it's nowhere near the amount of trash that could be removed by a functioning PCV system(which works via constantly replacing crankcase "air" with filtered air). it will act like a plugged PCV system, anything that gets out is actually pushed out through what is normally the draw side of the system. you'll normally see evidence of that by finding a pool of oil in the intake tube near where the tube that runs near the valve cover is attached to the intake tubing.

[Michael Savage]

Never seen oil in my intake tube or well anything. Also you can't put a breather on the back because of the coil packs only location is the front.

[Schurkey]

Why is it that every thread you start makes me live up to my signature line? It's not like I hate you or have something personal against you.

 

Honestly, sometimes I think you're starting threads just to bait us.

 

Deleting the PCV is not a smart move. Better to figure out what if anything is actually wrong, and fix it rather than disable the PCV system.

Edited June 29, 2014 by Schurkey

[GP1138]

Honestly, sometimes I think you're starting threads just to bait us.

 

I've thought this since his first thread.

[skitchin]

I guess the main debate people have over this is whether the crankcase pressure is great enough to efficiently vent the blow-by. The HC's from blow-by are corrosive(and not to mention can dilute oil). So why route these corrosive gasses to the intake instead of the atmosphere? I guess it comes back to which method can remove the HC's more effectively and a PCV system seems to have the upper hand. Adding a catch can to the PCV system seems to be the best solution. Beyond that I'm in over my head

[RobertISaar]

consider that the breather attempts to filter anything going in AND out of it..... it can trap exactly what you're attempting to remove from the oil on the inside, which is going to hurt the operation of removing airborn junk from the oil even further.

 

a catchcan isn't a bad idea if you want to keep the intake tract cleaner.... allows stuff to be evacuated from the crankcase, MOST of it getting trapped in the can(with certain designs working better than others) and the EPA probably won't stomp a hole in your face if/when there is a visual emissions inspection.

[George]

I think the main reason most people delete the PCV breather system is to NOT suck hot air from the engine back into the intake. Colder intake air charge is more dense, mix with more fuel = more power.

[Michael Savage]

Milzy Motorsports told me I could do it this way and said since I have the common issue of the rear valve cover breather coming out its optimal since I can't get it fixed. Replaced both grommets, and the tube itself along with the silicone and nothing prevented it from coming out so why have a vacuum leak when you can just delete the problem. Also are the corrosive gases from conventional or synthetic. Also I don't start threads to agrivate people or anything like that I usually do it to show a new mod I'm trying and to ask what to watch out for problem wise.

So far though oil hasn't leaked out of it or soaked the breather, and still running better than with that vacuum leak.

[Schurkey]

I think the main reason most people delete the PCV breather system is to NOT suck hot air from the engine back into the intake. Colder intake air charge is more dense, mix with more fuel = more power.

You cannot really believe that the few CFM of "hot air" from the PCV system (which is designed to meter (restrict) flow at idle, and has little manifold vacuum at heavy throttle) makes a bit of difference compared to the hundreds of CFM pulled through the normal intake tract at WFO/high RPM. It's even more ridiculous at part-throttle, where you're deliberately limiting the engine power.

 

Does pissing into the ocean raise the ocean's temperature?

 

A (slightly) more-meaningful argument would be that someone doesn't want all that "contaminated" air going into the intake manifold and "gumming-up" the plenum, ports, and valves. The answer here is that unless the engine has heavy wear or mechanical defect, there's little "contamination" in the PCV airstream that isn't moisture vapor, and yes, over thousands of miles the little bit of hydrocarbon or other fumes can coat the inside of the ports; all of which means very little for performance OR driveability. It's just not a problem big enough to spend a lot of time on. You have a hundred-thousand mile engine, and you just can't stand to have some carbon in the intake and ports? Get a can or two of Seafoam or whatever your favorite engine-gunk solvent is, and have fun for a weekend. Don't expect the engine to run any different when you're done--provided it was in mechanically good condition to start with, and you put it back together properly.

[RobertISaar]

I think the main reason most people delete the PCV breather system is to NOT suck hot air from the engine back into the intake. Colder intake air charge is more dense, mix with more fuel = more power.

 

care to guess as to how much the air density changes from the tiny amount of slightly warmer than intake manifold surface air makes, especially once the air hits the lower intake where the bottomside of it is exposed to whatever temperature the oil is? or the heads that are going to be near coolant temps? there is a LOT of metal to radiate heat into the airmass along the way.

 

i'm positive you cannot measure the difference on a dyno outside of its margin of error, or in any well planned real-world testing. there just isn't enough air moving through the system to effect airmass temps with any significance.

[RobertISaar]

Also are the corrosive gases from conventional or synthetic.

 

 

 

So far though oil hasn't leaked out of it or soaked the breather, and still running better than with that vacuum leak.

 

corrosive gasses aren't from the oil, they're from the fuel. gasoline itself is a pretty good solvent, burning it also produces acids, which when it slips past the piston rings ends up in the crankcase.

 

 

 

also, you've had it on for how long? the average PCV valve lasts beyond 50,000 miles, how long is the filter element going to last before it is too restrictive to let anything out? i've seen a brand new breather blow oil out of it on a heavily boosted engine under load. where that oil ends up is either on the road(fucking great, i love oil on the road), on the underside of the car(which isn't too bad assuming it doesn't stick near some of the hotter exhaust components) or somewhere in the engine bay where it becomes a fire hazard. L67BBQ? nope, anythingandeverythingBBQ.

[Schurkey]

Milzy Motorsports told me I could do it this way and said since I have the common issue of the rear valve cover breather coming out its optimal

It's a short-cut "hack", apparently promoted by folks who just lost a bunch of my respect.

 

since I can't get it fixed. Replaced both grommets, and the tube itself along with the silicone and nothing prevented it from coming out

The PCV system worked when it was new. The design is not faulty. There's a parts problem you haven't found yet. Diagnosis is the hallmark of auto repair; anybody can throw parts at a problem.

 

are the corrosive gases from conventional or synthetic.

Conventional or synthetic oil??? Either one. Either conventional or synthetic oil can "out-gas" the lighter, more-volatile components. Some oils lose more to this volatility than others. Less is better. This is not a big concern. The main thing you're removing with the PCV system is MOISTURE from the cylinder pressure (exhaust gas) that escapes past the rings. The fuel (gasoline, ethanol, diesel--any hydrocarbon) burns with air (oxygen). A major exhaust component is WATER, because the oxygen reacts with the hydrogen to form H2O. Small quantities of raw fuel coming past the rings is also a consideration.

 

The biggest single problem with the PCV system is when the rings no longer seal the cylinder, blow-by increases past the point where the PCV system is able to handle it. Pressure builds in the crankcase. That pressure will vent anywhere it can--it's supposed to go out whatever plumbing is supplied on what would otherwise be the inlet, filtered-air side of the PCV system, which routes it to the air cleaner or the throttle-body. If the pressure is so great that the PCV system still can't route the gasses, gaskets blow out, seals leak, the dipstick pops up out of the tube along with oil spray, etc.

 

For all I know, excess crankcase pressure is why your PCV system wouldn't stay in place.

Edited June 29, 2014 by Schurkey

[Michael Savage]

I've had it checked and checked stuff myself, but reading online probably 70% of all 3100/3400 have high crankcase pressure then because there's a million of threads about that rear PVC not staying on. And mine has no issues the scanners have picked up since it did this for at least 4 years if not always the hose poped out every drive eventually we put a wedge inbetween it to hold it down but this just seems more effective.

[RobertISaar]

scanner will show nothing about the PCV system. the PCM doesn't know or care of its presence. an oil analysis, that would tell you what is actually going on. but for better contrast, you would need an analysis of the same engine operated under the same conditions for the same amount of time.

 

that grommet does seem to be a common failure.... kind of like the oil pump drive seal. that problem has a permanant solution and it costs around $1. the grommet? haven't had to replace one myself so i don't know.

[dodgethis]

scanner will show nothing about the PCV system. the PCM doesn't know or care of its presence. an oil analysis, that would tell you what is actually going on. but for better contrast, you would need an analysis of the same engine operated under the same conditions for the same amount of time.

 

that grommet does seem to be a common failure.... kind of like the oil pump drive seal. that problem has a permanant solution and it costs around $1. the grommet? haven't had to replace one myself so i don't know.

 

just my 2 cents. It never ceases to amaze me, when I do a tune up, and replace PCV, that damn rubber grommet breaks off when I replace the PCV. I end up buying that GM help vacuum tube kit.

[Taylor]

Milzy Motorsports told me I could do it this way and said since I have the common issue of the rear valve cover breather coming out its optimal since I can't get it fixed.

 

Milzy has been around for a while, and I've SEEN some of the crap that they sell in person. They just want your money. To say a problem of a faulty PCV system can't be "fixed" is proof that they would rather you spend money on parts to them to bypass rather than a trip to the junkyard to get replacement or updated parts to actually address the original problem.

 

When I start to work on a vehicle, before I do anything "performance" to it, the first step is always MAKE SURE THE DAMN THING RUNS RIGHT FIRST!!!!!!

 

If you buy a car, and it does not run right, and you just jump right into your engine swap, and you get it all done, and it STILL does not run right are you dealing with a bad engine that you JUST swapped in? a bad computer? a bad wiring problem from what you just installed? a problem from the car wiring? a problem under the dash? a improperly connected tail light wire (i've seen that happen!)????????

 

Make sure the damn thing runs right FIRST. That alone is one of the best things you can do to these cars. THEN you look into performance, or harder to address things.

 

FYI, I had the bad pcv problem on my car as well. You know what caused it? Heat from the egr valve caused the plastic rear breather pipe to warp and crack. I replaced it with an updated style breather tube from a newer 3400 car, and problem solved. Total cost? A trip to the junkyard in Austin, $2 to enter the damn yard, and about $1 for the pipe itself (but I got several so still a good deal).

[Michael Savage]

My breather pipe isn't warped it just won't seat into the valve cover and that's where I get the vacuum leak. If you put a wedge between it and the ignition coil bracket it stays and is fine. Car runs fine. But I ended up swapping back to the PCV system because I was burning oil faster. But all in all I noticed no difference other than it not causing a vacuum leak from vibrating out of the hole.

[Taylor]

I'm having trouble even figuring out how it could cause any issues. It connects the rear valve cover to the air intake. Its not one of the "vacuum" lines that causes issues due to air being pulled in to the intake.

 

Of the actual vacuum lines, there is 1, the one that goes from the fuel pressure regulator to the MAP, and 2, the one that goes from the PCV to the top of the intake manifold next to the throttle body then back to the EVAP purge solenoid, then there is 3, the one that goes from the back corner of the manifold by the alternator to supply vacuum to the cars interior accessories, then there is 4, the BIG ASS ONE that connects to the brake booster, and then the last one I can think of is 5, the metal one on the front corner near the throttle body that goes down to connect to the transmission shift modulator. Those are the only "vacuum" lines on the car. That one that goes to the rear valve cover is not a "vacuum" line so I'm not sure how it could cause any kind of drivability problems (hell, I've forgotten to put it into the car completely and other than an annoying whistle noise, had no issues with drivability.

 

I would stick a new PCV valve on it, and then either wedge your old pipe, or get a different style one that fits better, and call it a day. This is definitely a head scratcher.....

[Michael Savage]

The one that goes from the PCV to the top of the intake manifold next to the throttle body that connects to the Evap on the other side. The air goes from the air box tube to the rear valve cover then goes though the PCV and into the intake behind the throttle body. If the one on the rear valve cover comes out and isn't connected it vacuums in unmetered air. It doesn't cause a major issue, but it's a vacuum leak and makes the car dump more gas and yeah. With my setup the way I can tell if I have a vacuum leak is. If I drive for an hour and I can rest my head on the manifold without getting burned it's perfect. If it's too hot and burns I've got a vacuum leak to look for. Atleast that works for me.

 

But with the PCV sucking in unmetered air from the rear valve cover and with it connected properly you'll notice on your scanner it reads differently.

[Michael Savage]

But side note I'm planning on going and ripping one off a 3500 here soon people say that one fixes it, and should be swapping into a 97 cutlass supreme so I can finally get a nice tune.