Scratchin my bald-ass head here.

[fastpakr]

Same. 100% not a giant vacuum leak.

 

[85_Ranger4x4]

Yeah, that side of it isn't a vacuum seal, it is just pulling air from atmosphere rather than the air filter housing on mine.

I have never had an engine that cared.

 

[pentode]

I woke up this morning thinking about PCV valves, dang it

I'm obviously not aware of every design that's ever existed but I believe the principle is always the same. High vacuum situations (like at idle) pull the check ball/disc /flap against the spring to close the valve. As vacuum drops, the spring has enough force to open the valve and more gases are scavenged.

I'm thinking if you put a breather where the oil filler cap is, you might reduce the scavenging effect on the other bank to almost nothing, which might lead to deposits etc in the long run.

Edit: so, you have minimum scavenging and no big vacuum leak at low RPM/ throttle closed and max scavenging at wide open throttle/high rpm, which is when you'd want it.

 

[85_Ranger4x4]

I woke up this morning thinking about PCV valves, dang it

I'm obviously not aware of every design that's ever existed but I believe the principle is always the same. High vacuum situations (like at idle) pull the check ball/disc /flap against the spring to close the valve. As vacuum drops, the spring has enough force to open the valve and more gases are scavenged.

I'm thinking if you put a breather where the oil filler cap is, you might reduce the scavenging effect on the other bank to almost nothing, which might lead to deposits etc in the long run.

Edit: so, you have minimum scavenging and no big vacuum leak at low RPM/ throttle closed and max scavenging at wide open throttle/high rpm, which is when you'd want it.

The oil cap side is just a breather, literally.

 

[PetroleumJunkie412]

I woke up this morning thinking about PCV valves, dang it

I'm obviously not aware of every design that's ever existed but I believe the principle is always the same. High vacuum situations (like at idle) pull the check ball/disc /flap against the spring to close the valve. As vacuum drops, the spring has enough force to open the valve and more gases are scavenged.

I'm thinking if you put a breather where the oil filler cap is, you might reduce the scavenging effect on the other bank to almost nothing, which might lead to deposits etc in the long run.

Edit: so, you have minimum scavenging and no big vacuum leak at low RPM/ throttle closed and max scavenging at wide open throttle/high rpm, which is when you'd want it.

That has been me for a few weeks. Trying to figure out how to totally eliminate the PCV returns for my intake track because I'm paying a small fortune to have my supercharger reworked. Down to a exhaust based evacuation system, or a high volume vacuum pump pulling vacuum on my crankcase.

 

[cbxer55]

I'll have to see what happens. Last night coming home from work, hammered it a few times. Running extremely well right now, better than it has for a while. All because of said breather? I still think the 28 year old 209,000 mile PCV is plugged up, and the breather fixed it. Didn't fix the PCV, but is letting the crankcase breathe again?

As for the MAF, not sure what I will do with that. Replace it or just fookin leave it. I can't believe it run s so good with it being bad. As someone else said, maybe the program has data the ECU can fall back on that let it run just on the cam and crank sensors.

Just for giggles, I pulled the IAC plug. No change. Hmmm. I have a larger throttle body. Maybe when I installed that, I set the idle at a point where the IAC is irrelevant? The IAC is new, btw. Got it earlier this year. I don't get it. A scan shows so many codes, o2 sensors, o2 heaters, lean bank 1 & 2, inactive EVAP and EGR, etc. And yet it runs like a scalded cat. Unbelievable.

 

[pentode]

The oil cap side is just a breather, literally.

Isn't the oil cap sealed to encourage vacuum pulling from the other bank (in a V engine)? My oil cap has an o-ring seal.

 

[85_Ranger4x4]

Isn't the oil cap sealed to encourage vacuum pulling from the other bank (in a V engine)? My oil cap has an o-ring seal.

Not sure I follow...

The cap is sealed to encourage the air to get pulled from the air filter housing not just whatever is floating around the engine bay.

The air going into the oil cap is only the vent, air has to get back into the engine as fast as it is sucked out via the PCV.

 

[cbxer55]

The oil cap has an o-ring because theoretically, if you remove it while the engine is running, it should be a vacuum leak since the incoming air is not being sourced from the intake and the MAF. It's called unmetered air. Which is why I don't get that my truck runs so good with a crankcase breather on the oil filler hole. With the oil cap off, engine idling, I put a folded paper towel over the opening and did some revving. If the PCV was working, when revving, the paper towel should get sucked down and try to enter the opening. It doesn't. Also if there was excessive blowby, the paper towel would get puffed up away from the opening. It just sits there and does nothing. Article I read on my phone said it's likely the PCV is plugged, due to many factors, including my sister driving the truck for 42,000 miles and not changing the oil.

I believe the PCV valve on the 3.0 is under the upper intake manifold on the driver's side. Cannot see the valve cover since the upper intake leans over that part. Would need to remove the upper intake in order to fix it. Not feeling the desire to do that any time soon, since the truck doesn't seem to care about the issue. Doesn't seem to care about the MAF not working either. And apparently, since I can pull the connector on the IAC and nothing changes, it must be not doing anything either. ODD!

 

[pentode]

Not sure I follow...

The cap is sealed to encourage the air to get pulled from the air filter housing not just whatever is floating around the engine bay.

The air going into the oil cap is only the vent, air has to get back into the engine as fast as it is sucked out via the PCV.

Yeah, sorry, I was so focused on trying to explain why a properly working PCV valve doesn't cause a massive vacuum leak that I lost sight of the fact that on the 3.0, the oil filler side is the breather side. Mea culpa on that.

 

[pentode]

I believe the PCV valve on the 3.0 is under the upper intake manifold on the driver's side. Cannot see the valve cover since the upper intake leans over that part. Would need to remove the upper intake in order to fix it. Not feeling the desire to do that any time soon, since the truck doesn't seem to care about the issue. Doesn't seem to care about the MAF not working either. And apparently, since I can pull the connector on the IAC and nothing changes, it must be not doing anything either. ODD!

Went to look at my 3.0 just to make sure I wasn't misremembering something else but the PCV is a the back of the driver's side head - doesn't look like you need anything special to swap it out, removing the intake or anything like that.

 

[cbxer55]

Yeah, sorry, I was so focused on trying to explain why a properly working PCV valve doesn't cause a massive vacuum leak that I lost sight of the fact that on the 3.0, the oil filler side is the breather side. Mea culpa on that.

The oil filler capon my Lightning is on the breather side. So it was on the 4.0 Moostang I once owned.

I can certainly understand the PCV not causing a big vacuum leak at idle, vacuum sucks the rattle ball up and blocks the flow. But if the opposite is true, when vacuum goes away when you stomp on the loud pedal, then that breather I put on the passenger side should cause issues when I do so. It doesn't. Goes from idle to full throttle with no issues.

So yeah, still scratchin my head here.

 

[pentode]

The oil filler capon my Lightning is on the breather side. So it was on the 4.0 Moostang I once owned.

I can certainly understand the PCV not causing a big vacuum leak at idle, vacuum sucks the rattle ball up and blocks the flow. But if the opposite is true, when vacuum goes away when you stomp on the loud pedal, then that breather I put on the passenger side should cause issues when I do so. It doesn't. Goes from idle to full throttle with no issues.

So yeah, still scratchin my head here.

I think the way my crappy memory works, I was thinking the PCV was next to the filler cap, not thinking about where the plumbing actually goes. (I work on a bunch of different cars and am clearly going senile)

But having looked that the plumbing on mine this morning, you'd just be pulling air straight from the engine bay vs through the intake hose as 85_Ranger said. So, 6 and two threes as the Brits say.