scared meself!!!

[tom4bren]

What are you talkin' about Tom. The brand new Eye-suzu engine that I put in mine hasn't burned a drop of oil for over a year now. I still check it religiously, but to date those extra little holes that they drilled in the pistons seem to be doing their job.

Good for ye. But I'm talkin about a $2 fix to keep from needing a new engine.

[tom4bren]

Oh boy, here we go again...Not to start a major debate or anything but, the PCV does indeed provide positive crankcase ventilation, hence the name! Equalization of pressure is conveniently provided by the oil drainback passages in the heads and block, there are no internal valves to retain pressure in either. The oil "spluge" described coming from the dipstick tube or the PCV or the oil cap is from worn piston rings 99.999% of the time. (I did see once where a piston had been holed by too hot of plugs but how often does that happen? The oil spit out of an open oil filler neck is as Tom suspected, merely spash, not pressurized oil. Worn valves won't pressurize the crankcase as they do not have an open passage to the crankcase. They will cause a loss of compression and backfiring through the intake manifold if it is the intake valves that are worn. Worn valve seals can leak oil into the combustion chambers to be burned off during operation but even they will not pressurize the crankcase. As far as the returning oil flow being somehow pressured into blowing back through the return passages, highly unlikely as the oil return passages are far more voluminous then the pressure passages. Could it happen? Only if the return passages were so sludged-up and restricted as to cause a positive-pressure environment within the return-oil system. If that's the case, the owner of said auto has far greater things to be concerend about, namely, no oil gettin' to nothin'...

Good points ... but I think I'm on to sumpn here. Quit pee'ing on my charcoal.

[Scott Larson]

Best-o-luck to ya Tom, as long as ya keep oil in yer sumpn'! Please do keep us posted as to yer findings! Oh, and just calls me "Smoky Da Bear"...although I ain't from Chiicaagoo or nuttin' like dat dere...Go Bears!!

[Y33TREKker]

Nope ... I did not contradict meself (that would be counter productive to my current record of never being wrong). The PCV valve is there to prevent PCV,

Heh, you just made another contradiction. The PCV is there to PROMOTE positive crankcase ventilation. :P

which is why many laymen actually mistakenly refer to the little plastic thinggy on your left hand valve cover as the Pressure Control Valve (PCV).

Mebbe, but no one HERE mistakenly referred to it as a Pressure Control Valve.

The bottom line is that you should NOT have pressure inside of your valve covers - they just can't handle it. Valve covers have a direct line to your oil pan

You see, you just contradicted yourself AGAIN with regards to what you said in your earlier post.

What is the current mechanism for pressure leveling between the two valve covers though ... through the block? Don't think so.

What was your mechanism of delivery by the way? I didn't see an answer to that question.

so any pressure is bled off by ... oil leaks - at the valve covers, or the oil pan, I've even seen it shoot out of the dipstick tube.

Which is what Positive Crankcase Ventilation systems were created to address in the first place. Excess pressure wasn't MEANT to be bled off by oil leaks at the various engine gaskets (oil pan, valve cover, or dipstick tube), that's just where it ended up being bled off sometimes because the gaskets and/or dipstick had been blown out by the excess crankcase pressure.

Where does that pressure come from you ask? Blow by from the valves (probably blow by from the rings too but that's food for a different discussion).

Yeah...I didn't ask, because I already understood that the pressure in question DOES come from blowby past the rings and not the valves (intake and exhaust) as you just suggested.

The only way that the right valve cover pressure can be relieved through the PCV is for the vapors to flow through the oil pan & back up the other side to the left valve cover to exit through the PCV. That's just asking for more vapor borne oil to get burned off through the combustion chamber & IIRC, that's what we're trying to avoid.

Again though, we're talking about vapors that are going to be pressurized equally throughout the entire system of passages (in the engine block and heads) in the PCV system. You're equating that principle with basic flow and it's just not the same.

It sounds like we aren't going to ever reach the point of agreeing to agree so until I try out my cross over idea, lets just agree to disagree. It's gonna be SCHWWEEEETT to prove you wrong though.

Hey, I'd be the first to agree that we aren't going to agree about how a PCV system works based on your apparent current understanding of such a system...any more than I'd agree with anyone at the moment who might tell me that once you determine your crossover idea isn't in fact necessary, you'll be back on here SCHWWEEEETTLY admitting that you were wrong.

[Y33TREKker]

...The oil spit out of an open oil filler neck is as Tom suspected, merely splash, not pressurized oil...

In my own defense, I didn't say pressurized oil, but I meant, and SHOULD have said, "oil vapor".

[tom4bren]

OK trekkie. Yer right about the source of the pressure not coming from blow by on the valves. I just pulled that one out my arse on the spur of the moment and later regretted it (but not enough to go back & edit the post). It's probably a combination of blow by on the rings and simple heat expansion of the air in the oil system.

Yer also right in how I used the acronym PCV. The V part does in fact ruin the point I was trying to make.

Yes, the fact that I'm admitting that you were right is paramount admitting that I was wrong.

I won't hesitate however to post my results (positive or negative) whenever I get around to putting on a crossover pipe. If for no other reason than to prove you wrong. Negative results are almost as beneficial as positive results as long as you learn from them. My first attempt at reducing oil consumption did not cure the problem but it certainly helped (& shouldn't have by your logic).

Question: If a crossover pipe on the valve covers will be of no benefit in your opinion, how do you feel about crossover pipes on a dual exhaust?

[Y33TREKker]

OK trekkie. Yer right about the source of the pressure not coming from blow by on the valves. I just pulled that one out my arse on the spur of the moment and later regretted it (but not enough to go back & edit the post). It's probably a combination of blow by on the rings and simple heat expansion of the air in the oil system.

Yer also right in how I used the acronym PCV. The V part does in fact ruin the point I was trying to make.

Yes, the fact that I'm admitting that you were right is paramount admitting that I was wrong.

Just remember that it's only been you who has been making it so much a matter of who is "right". I was simply trying to save you some unnecessary effort based on your idea about how the kind of system you're wanting to modify actually works.

And seriously, trekkie? Again? You do realize how you make yourself look when you do stuff like that don't you?

I won't hesitate however to post my results (positive or negative) whenever I get around to putting on a crossover pipe. If for no other reason than to prove you wrong. Negative results are almost as beneficial as positive results as long as you learn from them.

That you're automatically assuming that your results will prove me wrong regardless of what they are says a lot about your probable methodology and interpretation of your own results.

My first attempt at reducing oil consumption did not cure the problem but it certainly helped (& shouldn't have by your logic).

Seeing as how I don't know what your first attempt even was, I can't respond to your comment about what logic you're even referring to or whether you proved it wrong.

Question: If a crossover pipe on the valve covers will be of no benefit in your opinion, how do you feel about crossover pipes on a dual exhaust?

First of all, you're assuming that the two situations are the same and they're not. Crossover pipes in exhausts are meant to equalize pressures from both sides of an engine that are positive all the time with no source of vacuum to relieve that pressure. That kind of crossover pipe is just used to try to further equalize the BACKpressure in a dual exhaust system.

But the fact of the matter is that a PCV system on an engine ALREADY has a crossover pipe of sorts that's achieved with the oil drainback passages in the heads and block that Scott referred to earlier, making a crossover tube from valve cover to valve cover redundant (which is pretty much all I've been saying).

[Scott Larson]

In my own defense, I didn't say pressurized oil, but I meant, and SHOULD have said, "oil vapor".

Duly noted Trek. It's really not even "oil vapor" as much as it is simply mechanically splashed oil being flung out of the open filler neck. The only thing nobody can argue is that it makes one hell of a mess... Rustproofing, yea that's it!

[PK]

Hmmmm - working on my 6VD1 engined 3.2L VX today, I noticed what might be another difference.
(Or it could just be that you guys need to look at your own engines a bit better).

Standing at the front of the vehicle, looking at the engine, the PCV valve is in the right hand side rocker cover, and after the PCV valve the hose connects to the intake manifold just after the throttle body.
Now look to the left hand side rocker cover. At the same place as the PCV valve is on the right, another hose comes out of the rocker cover, but without a PCV valve. That hose connects to the intake air pipe, just in front of the throttle body.
Is that LHS hose the type of cross over you had in mind Tom??

Remember, my 6VD1 engine does not burn oil to the point of needing to be topped up between oil changes - it drops about 1/3 of a quart in 3000 miles.

Comments appreciated.

PK

[Scott Larson]

That's called a positive ventilation hose and is a mystery to me in that it dumps into the intake before the throttle body allowing unfilterd and most likely oil-misted air to dirty-up the throttle body. Just one more thing about these engines that confounds me as to what the boys at Isuzu were thinking... As to providing a pressure balance between the valve covers, it would not.

[Y33TREKker]

Duly noted Trek. It's really not even "oil vapor" as much as it is simply mechanically splashed oil being flung out of the open filler neck. The only thing nobody can argue is that it makes one hell of a mess... Rustproofing, yea that's it!

Oil being flung sure isn't the only thing it's looked like even when I've ever just had my engine running with the oil filler cap off, and that's not even considering the possible air currents that would be occurring under the hood while driving, but I'm not going to get into an argument about it when I've seen it for myself.

[Scott Larson]

Nor would I consider arguing the point Trek. As you have seen the results first hand, you don't need an explanation. For those not as well versed, when looking down the oil filler neck on the passenger side valve cover, you will notice the cam gear assembly directly below that opening. Now imagine that assembly, rotating at speed, bathed in a constant oil flow, flinging the oil out an open filler neck cuz someone left the cap off...yup, it makes a helluva mess! I've never done it, but in these hurried times, I completely understand how it happens.

[Y33TREKker]

Nor would I consider arguing the point Trek. As you have seen the results first hand, you don't need an explanation. For those not as well versed, when looking down the oil filler neck on the passenger side valve cover, you will notice the cam gear assembly directly below that opening. Now imagine that assembly, rotating at speed, bathed in a constant oil flow, flinging the oil out an open filler neck cuz someone left the cap off...yup, it makes a helluva mess! I've never done it, but in these hurried times, I completely understand how it happens.

Yes, the results I've personally seen first hand as it was happening was more akin to pressurized oil vapors, and not oil being slung. Oil being slung obviously seems to be the only thing you've imagined, and yes, I can imagine that too, but that's not what I've been saying.

Why Isuzu didn't see fit to include a baffle plate under the filler hole in that valve cover to aid in condensate collection and drainback like I've seen on other valve covers is a mystery, but the fact remains that they didn't on the VX. Maybe the engineers at Isuzu were just giving people more benefit of the doubt at the time though since everything was so much more slower paced that far back at the turn of the millennium.

[tom4bren]

Just remember that it's only been you who has been making it so much a matter of who is "right". I was simply trying to save you some unnecessary effort based on your idea about how the kind of system you're wanting to modify actually works.

Mucho appreciado ... but I've already wasted more time on this discussion than it'll take me to add a temporary line to try it out ... so it's worth a shot.

And seriously, trekkie? Again? You do realize how you make yourself look when you do stuff like that don't you?

My abject apologies. I honestly didn't consider the fact that you'd view an honorific of your online monicker as a denigration. I suppose I need to apologize to wormgod for calling him wormy, crotchrocket for calling him pocketrocket, yellowgizmo for calling him giz, cobrajet for calling him double G, & mostly to referring to Jo as the Whore Jockey.

Gentlemen: My apologies. Sincerely, T4B.

BTW Mr Trek, the first two sentences are sincere, only the last part is dripping with sarcasm.

That you're automatically assuming that your results will prove me wrong regardless of what they are says a lot about your probable methodology and interpretation of your own results.

Nah. That's not what I was saying at all. Proving you wrong is IRT the comment that I would be too chicken to post that I was wrong.

Seeing as how I don't know what your first attempt even was, I can't respond to your comment about what logic you're even referring to or whether you proved it wrong.

I'm sorry. I thought for sure you had read this thread: http://www.vehicross.info/forums/sho...ht=interesting.

First of all, you're assuming that the two situations are the same and they're not. Crossover pipes in exhausts are meant to equalize pressures from both sides of an engine that are positive all the time with no source of vacuum to relieve that pressure. That kind of crossover pipe is just used to try to further equalize the BACKpressure in a dual exhaust system.

Nope. I wasn't assuming anything at all. The exhaust is an open system & the crank case is a closed system. There are similarities involved though. Primarily the fact that most people feel that crossover pipes on a dual exhaust system are a waste of time & effort. All I know is that the one time I added them to my rig ... it made a HUGE difference. That's where the analogy ends.

But the fact of the matter is that a PCV system on an engine ALREADY has a crossover pipe of sorts that's achieved with the oil drainback passages in the heads and block that Scott referred to earlier, making a crossover tube from valve cover to valve cover redundant (which is pretty much all I've been saying).

& all I'm saying is that your reliance on the drain back ports being adequate to handle both the returning oil and flow of air/oil mix from the right to the left valve cover may or may not be grounded. The older the engine is, the more blow by from the rings there is so there will be more flow of the air/oil mix that needs to be accounted for. Whilst the single PCV was adequate on a new engine, it may not be now.

Look at it this way: Assume that the oil pump is pumping 1 gallon per minute at highway speeds (probably overly conservative). Further assume that there are 12 1/4 in holes in each head for oil return (Guess on my part because I have no idea how many returns there are or how large). That means that the oil returns need to pass 232 cubic inches of oil per minute through a total area of less than 1.5 square inch. That doesn't leave much room for the airflow does it?

[tom4bren]

Maybe the engineers at Isuzu were just giving people more benefit of the doubt at the time though since everything was so much more slower paced that far back at the turn of the millennium.

Rekin I proved them wrong, didn't I?