sounds like the charcoal cannisters that was part of emmisions they used vacuum to draw fuel vapors from the tanks . if you have vented fuel caps it shouldnt hurt not to run them

 

No, I don't think I have vented fuel caps. But I am considering buying some locking gas caps...not sure if those are vented or not.

 

I'm not sure what else to tell you. Your claim goes against basic physics. If you suck through a straw, air moves through the straw. If you put your finger on the end of the straw, you can't suck air through anymore.

A PCV system is the exact same idea. If there's no breather filter and the system is closed off, blowby cannot move. But since the vacuum signal on the source-end is just as strong, positive atmospheric pressure will force its way through the weakest seal on the engine, be it an oil pan gasket, valve cover gasket, or what have you.

This isn't about me hijacking this thread; you're giving bad advice and I'm calling you out on it for the benefit of the OP. There's a reason it's called positive crankcase ventilation. If I'm wrong and you're right, then why have PCV systems been set up this way for over 40 years? Do you think Ford would waste the money installing breather filters on millions of vehicles for decades if it was the wrong way to do it?

 

Yes, in this I agree, your right that's exaclty what happens, I'm saying that it is a good thing. That having a vacuum and thus thinner gasses in the crankcase is good, and that pulling air in through the weakest seals is good. It prevents leaks and improves power.

Many many less then ideal things have been done by Ford and many other manufactures for many many years simply because that is how it has been done before. By that logic we shouldn't use a PCV either because draft tubes worked just fine for many decades. This doesn't make it the best way to do it. I'm sure we all have examples, even many that continue to this day. So YES I think Ford did waste money installing breather. Just as they waste money and risk our lives with C-clip axles, and many other poor choices. Engineers aren't perfect, Ford isn't infalable, want a list?

Tell me why, outside of "because that's how Ford did it" you think a breather is better?

 

Pulling air through the weakest seals is not good. Pulling air through weak seals is going to make them weaker. The whole point of a PCV system is to pull the displaced air through a breather filter and not through a weak seal. Seals are supposed to seal. They're not supposed to let something pass through them. If the PCV system was intended to pull the displaced air through the seals in the engine, then how would the system work on a brand new engine? The breather filter gives the negative pressure an easy, non-obstructed path to move through without disrupting the seals on the engine, because those seals need to...well, seal.

Trying to pass something through a seal does not prevent the seal from leaking.

You said yourself that the PCV system is a controlled vacuum leak, which is correct. If the PCV system was supposed to pull fumes out of a closed system, it wouldn't be a vacuum leak. The goal is that they're moved through (and displaced with clean air pulled in through the breather filter) at roughly the same rate that the rings let blowby escape past. This way, blowby fumes do not remain stagnant in the crankcase. When the rings begin to age, more blowby is pushed into the crankcase than the PCV system can pull through. That's when you see issues similar to what the OP is seeing.

You make a great point; just because Ford did it doesn't mean that it's right. But in this particular example, if the PCV system could have been improved by simply removing the breather filter, I really think that an automotive engineer would have already stumbled upon it sometime over the last 40 years (and not just at Ford). It's the same argument for people who say you should remove your thermostat - if automakers really could have made that cost savings, believe me, they would have. When it comes to things as simple and tried and true as systems like this (including PCV), it's so well understood that by now, if something is on the engine, it should be.

That doesn't really matter in this case, though, because the PCV system is so basic that none of it is a mystery - it's simple physics. When you drink through a straw, you suck on one end, and iced tea moves through on the other end. If you were to seal off the top of your glass of iced tea and around the straw, the fluid level in the glass wouldn't be able to drop, and iced tea would not flow out of the straw when you sucked on it. When you suck air out of a balloon, the balloon must shrink. If the balloon was rigid and couldn't collapse, you wouldn't be able to suck the air out of it. PCV works on the same principle.

 

in his original post the op states engine runs good with pcv hose off and open to air, but goes back to crappy when you plug it. wouldnt it make sense that removeing or plugging the breather would have the same effect as plugging the hose? (engine goes back to crappy)

 

Just so everyone here knows, I apparently fixed it. I put the pcv valve back like it was supposed to be and put a new breather in on the other side and now it runs perfect!! What I want to do though is put the pcv valve on the other valve cover (pass. side rear) and the breather on the other (driver side front) so that it would be easier to add oil.

 

rockin a good to hear shes runnin right! should be no hassle switching to the way you described it will still function the same

 

Awesome; glad to hear the new breather fixed it.

 

Yes and no, your right in a way I'm saying it's better to leak in then out, but take a close look at a front cover or rear main seal sometime, there not really solid seals, more like swipers. There more like round windsheild wipers then gaskets. Or using your straw example more like the plastic lid that the straw goes through in a fast food cup. Because of this sucking in on the seal tends to suck it tighter to the crankshaft.

So our only real disagreement is the nature of engine oil seals and a stratagy to keep them sealed. I'll do things my way and make my recomendations and you can yours. I however do this stuff for a living and can't tell you how many engines have been improved by such a small change. In a way your right that having balenced pressure one either side of a seal is easier on it, that a small leak can be a good thing, keeps the seal lubbed, and well a little oil never hurt anything. However this balance is disrupted easily with blowby either at high throttle or hi mileage and I've seen countless oil leaks stopped in this manner while improving other aspects. I've seen cars get holes in there oil pan and not leak oil until the engine is shut off. I've seen old trucks with stock systems that blow oil out so bad they cover the cars behind them with a mist on the highway fixed with a PCV mod. In my daily I run a direct manifiold vacuum line to each valve cover, 280,000 miles, synthetic oil, a heavy foot, not a single drop of oil, and runs like a champ.

 

the op's truck is fixed, he installed a breather, now says running fine