removing pressure line from oil filler?

not unless you want crankcase ventillation issues. That hose allows air back into the crankcase as well as assisting the other PCV line in venting at WOT.

I would NOT delete it (unless having the crankcase under vacuum is desired).

Good luck.

You could theoretically introduce unmetered air into your engine, causing a lean situation. Granted it would be a small amount..

I assume you are getting a C&L inlet - does it not have a provision for the line? The last CAI I installed had a dimple where to drill the hole (it did not come predrilled though).

It would be best to leave it stock - the SN's run lean enough as it is without having unmetered air and vac leaks.

Good luck.

deadlast said:

i see, so what happens if i just leave it open?

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This is what happens if you leave it open or leave it open with a breather:
How the PCV system works
The PCV (positive crank case ventilation) system draws air from the crankcase into the intake stream and into the combustion chamber where it is burned in order to reduce emissions. This system does more than reduce emissions, it positively ventilates the crankcase prolonging engine life, whereas running a breather cap system even with the PCV valve capped or filtered to the outside is a passive system rather than a positive system like the PCV, and is not as efficient at ventilating the crankcase as the PCV system as our newer emissions friendly engines do not have road draft tubes like older muscle cars did in order to create the positive ventilation effect that the PCV valve does. Also remember that the PCV system is an emissions component, and if it is deleted or changed some states may fail the visual portion of your emissions test.
Why not to run a filtered breather cap
One should never run a breather cap with a functional PCV system (with the oil filler neck capped or connected) as the breather cap allows unmetered air from the engine bay to enter the crankcase and then the intake charge via the PCV valve which creates a lean condition. This lean condition may cause detonation\pinging (a common problem with SN95s in stock form) to occur, and it is important to note that detonation is not always audible so you may not know that you’re pinging. This lean condition is created because the PCV system draws fresh metered air into the crankcase via the oil filler neck hose in order to replace the oil vapor laden air that the PCV valve drew out of the crank case into the intake charge. This is a 1:1 swap so the air fuel ratio is affected, and prevents a vacuum from forming in the crank case when the PCV valve draws the air out of the crankcase. If one runs a filtered breather cap the the intake charge still has 100% if the intake charge’s air as no air was diverted to the crankcase, and now the additional air from the crankcase is added to the intake charge leaning the air fuel mixture.
Capping the filler neck hose
One should not cap the oil filler neck to throttle body PCV hose in order to reduce oil in the intake charge as that hose is bi-directional (with the correct non breather oil cap or even with a filtered breather cap). The PCV system draws fresh metered air into the crankcase in order to replace the oil vapor laden air that the PCV valve drew out of the crank case into the intake charge. This is a 1:1 swap so the air fuel ratio is not off and prevents a vacuum from forming in the crank case. If the PCV valve cannot keep up with the pressure inside of the crankcase the extra pressure can be relieved via the oil filler neck hose. Capping off the PCV oil filler tube with the proper oil cap prevents the extra crankcase pressure relief, contributes to a vacuum in the crankcase, and contributes to a lean condition as no air is diverted to the crankcase from the intake charge while air is added to the intake charge from the crankcase. Capping the oil filler neck with a filtered breather cap allows unmetered air to enter the intake charge from the engine bay via the crankcase, through the PCV valve.

Tim

deadlast said:

ok thanks, i will have to make a hole then for the tube.

Click to expand...

Yeah Andy (Rio5.0) drilled a hole in his C&L inlet pipe and attached a hose fitting to the hole in order to connect the hose to. It looks great and works well too. He told me just to make sure that the hole is upwind if the ACT sensor so no oil vapor gets on the sensor.
Tim

i dont understand how using a filtered breather cap is bad for the engine. people have been running setups like that for years with no detonation problems. i dont think you can possibly add that much unmetered air to cause a lean condition. so ur saying that the only solution to this problem is never to change the stock valve cover to TB hose? i know of a lot af aftermarket TB's without that hose end? why's that

ninety15.0 said:

i dont understand how using a filtered breather cap is bad for the engine. people have been running setups like that for years with no detonation problems. i dont think you can possibly add that much unmetered air to cause a lean condition. so ur saying that the only solution to this problem is never to change the stock valve cover to TB hose? i know of a lot af aftermarket TB's without that hose end? why's that

Click to expand...

You can naturally believe what you want, but in my previous post I detailed exactly how the PCV system works and if ANY unmetered air is introduced into the intake charge the air\fuel ratio will be lean which is a cause of detonation which is not always audible so people may not know there is a problem. This was not a problem in the carb days because of the way the PCV system for them was set up (when they had them), but with a computer controlling everything the A\F ratio is exact with little room for error and no room for extra air.
The cliff's not version for your point is that the filtered cap lets in air via the crankcase through the PCV valve into the intake charge creating a lean condition. If you delete the PCV system and run straight breather caps you'll get no unmetered air into the intake charge, but the crankcase is not ventilated efficiently (or positively) and the build up of corrosive gases (no positive ventilation, only pressure release) will shorten engine life. Now if you run straigh breathers with a positive ventilation system like hoses connected to your VCs from the headers with a deleted PCV system that is a different story.
I've never seen any aftermarket TBs with no PCV hose attachment (only SN95s which have that port on the air intake or CAI) and for aftermarket VCs that have no filler neck with the PCV port for the hose go to fordracingparts.com and get part#M-6766-D302 which not only has the PCV hose port, but a built in oil baffle.View attachment 499666
Tim

thats confusing man...i dont think you know what the word via means. Secondly EFI stangs as im sure u know have only one pcv in the lower and nothin on one valve cover. Please explain to me how crankcase pressure equalizes internally as quickly as it appears if only one VC has a vent hose. Given the physical properties of the venturi effect (which is the principle on which the stock VC to TB vent is based) the air would be sucked out of the valvetrain so fast at WOT and so incredibly slow at any other part throttle application that it would be negligable (like being vented to atmosphere)...im therefore lead to believe that on a stockish 5.0 there just isnt enough pressure, or lack there of, to cause a problem with a filtered breather. plus why wouldnt all of us that do run breather/filters have longevity issues?

ninety15.0 said:

thats confusing man...i dont think you know what the word via means. Secondly EFI stangs as im sure u know have only one pcv in the lower and nothin on one valve cover. Please explain to me how crankcase pressure equalizes internally as quickly as it appears if only one VC has a vent hose. Given the physical properties of the venturi effect (which is the principle on which the stock VC to TB vent is based) the air would be sucked out of the valvetrain so fast at WOT and so incredibly slow at any other part throttle application that it would be negligable (like being vented to atmosphere)...im therefore lead to believe that on a stockish 5.0 there just isnt enough pressure, or lack there of, to cause a problem with a filtered breather. plus why wouldnt all of us that do run breather/filters have longevity issues?

Click to expand...

I feel your pain, as this is still somewhat confusing to me.
Here is what I know from troubleshooting my own pcv system. The engine vac signal is much stronger at the pcv (from the inside of the intake) compared to at the TB (outside the intake system). This is why air is usually not pulled out of the VC, but does travel through the PCV. Most often it is a 1-way system. The venturi effect is not really how the TB/VC line works, although it does increase the efficiency of the system. The primary driving force is the engine vac signal at the pcv. Also, keep in mind that pressure is not strongly dependent on flow. Pressure in the crankcase can change a great deal with only minimal flow, and it can decrease as quickly as it increases.

"What we have here is a failure to communicate!"
It sounds like ninety15.0 and 18mustangs are talking about 2 different systems.
The issue that is being discussed is whether or not an open element breather cap can be used on a pcv equipped car. The function of the pcv has been very well described in above posts so I will leave it alone here.

car 1
5.0 mustang with pcv and open element breather.
There will be fresh air pulled through the open breather, into the crankcase, past the PCV, and into the intake. None of this air is metered at the MAF, and none of this air is throttled at the TB. This will cause drivability issues, very similar to a vac leak. Things get even worse with stronger vac signals, which pulls more oil from the crankcase, fouling plugs and CC's.

car 2
Same car with pcv and VC/TB hose (no open element breather).
Air is now pulled from just before the TB and follows the same path, through the crankcase, pcv, then intake. The difference here is that the air flowing past the pcv in this scenario has been metered at the MAF, even if it is still not throttled at the TB.

my thoughts
jason

Try putting 10-14lbs of boost to your motor with the factory pcv/ filler neck tube hooked up and see what happens.

I'll deal with a little unmetered air over a pressurized crankcase any day!

mpe331lx said:

Try putting 10-14lbs of boost to your motor with the factory pcv/ filler neck tube hooked up and see what happens.

I'll deal with a little unmetered air over a pressurized crankcase any day!

Click to expand...

I did not know anyone was talking about forced induction on this thread. That is a totally different animal altogether and really should not be addressed in the same breath as a N/A PCV system.