Extra breather necessary?

redsn95gt · Dec 5, 2011

I have been having a problem with oil making its way into the intake manifold and even collecting at the throttle body. At first I thought my lower manifold needed machining but the machinist told me I probably have very high crank case pressure causing this problem. Its also causing the back of the lower manifold seal to blow out and leak down the back of the block. I have only a small breather on the passenger side cylinder head cover but I have plenty of room to put another breather on the driver side too. Would this help with my pressure problem?

I also thought it might be a good idea to install the steeda oil seperator kit to help collect some of this oil from the pcv valve and keep it away from the intake.

Any suggestions appreciated

Thanks!

VibrantRedGT · Dec 5, 2011

At this point you have no point but to add another breather. Are you running a PCV system as well? If so you can cap this and run dual breathers.

redsn95gt · Dec 5, 2011

Thanks. I don't have any other ventilation piped up besides the small breather (about 2.5" diameter) on the one cover and the PCV hose connecting the upper and lower intake near the throttle body, theres nothing more to it, and all the smog stuff has been deleted. So is the PCV hose even doing anything at this point? I'm running the smallest valve covers possible (modified stock fox covers) to keep a stock hood appearance so there's not a lot of room in them for air flow in them either, that is probably contributing to the problem as well.

So beyond adding a second breather, I was reading and saw that a larger air intake filter could help me increase air flow as well? I do have room to do this if it will help.

Thanks

BlackVert · Dec 5, 2011

the PCV valve is part of the "Positive Crankcase Ventilation" system. the vacuum from the intake "sucks" pressure from the crankcase that builds up, generally a little at a time from air getting through the rings on the compression stroke.

without it, too much pressure can build up ... not good

FastDriver · Dec 7, 2011

Some guys in here need to do a little more reading on your PCV system. It is integral to the long life of your motor. Moisture, a by product of combustion along with other chemicals that are adverse to the proper lubrication of the oil, work their way into your oil. The PCV valve gives these chemicals a place to go. The moisture that builds up in your oil will evaporate out of the oil if the oil is kept at an appropriate temperature. That's one reason not to run your motor too cool. Oil temps in the crankcase are usually 20-30 degrees warmer than your coolant temps. So with a 185* t-stat, your oil should be staying somewhere in the neighborhood of 205-215*, which is warm enough to boil off the water contaminating your oil.

Closing off the PCV system is not intelligent as there is no advantage in doing so.

Typically, the hose that connects your TB to your valve cover should allow clean "metered" air to replace the air in the crankcase, as the contaminated air moves into the intake. When you replace this hose with a breather, unmetered air will replace the air in the crankcase instead, which leads to a leaning effect on your intended tune. This is obviously not a point of concern if you're running speed density or can tune yourself.

If oil is collecting in the throttle body, then the air is moving the wrong way through this tube. That can happen as a result of a clogged PCV valve or hose. It can also happen on worn out blocks where there is more blow-by than even a 100% functional PCV can vent. If you want to treat the symptom, you can run a breather. If you want to fix the cause of the problem, you should focus attention on fixing the PCV system and then do a leak down test on the motor to see if it's time for a hone and new rings.

Don't pull off the PCV system, though.

Rick 91GT · Dec 10, 2011

Im assuming this is a NA combo? What intake? MAF car?

revhead347 · Dec 11, 2011

I thought you had a blower for some reason. There should be no reason to get so much pressure it blows the intake gasket out. Something is seriously wrong. I would start with a compression test to see if that bottom end is even viable.

Kurt

redsn95gt · Dec 28, 2011

Sorry for the delayed reply- just saw these updates forgot to subscribe to my own thread. This is a freshly rebuilt NA block with all new pistons and rings. Less than 15 miles on it as of now. Got good results on compression test. Did it a few times just to be sure, but I was in the green. I was running just a single breather with no fill neck and blocked the port going to the intake tube not realizing how critical it was for a line to be there. I've since done some reading on PCV theory and realized I was cutting off air flow. I am hoping that is what was wrong causing all the high pressure. So much air was getting into the engine with only a tiny breather to escape if it wasn't used in combustion and the PCV valve was almost useless. I'm doing some upgrades right now, I got the top end off now so I will also pull and inspect the PCV hose and the valve fitting to be sure its up to par. I will have new auto-meter oil pressure and water temp gauges and new injectors on for the next start up later this week. I replaced the breather with one that has a hose fitting to run a line back to the intake tube port to get some circularity to the air flow that actually makes the PCV function correctly.

As for the tune, you wouldn't know anythings wrong. The car was driving well and only having minor issues with idle at this point. I did all my own changes on Quarterhorse, but I'm by far no tuning guru. I just did the minor stuff to get it to do basic driving. I haven't pushed the motor past 5k yet. I just got concerned when I took it all apart to find all this oil up stream.

95opal · Dec 28, 2011

Your problem is with running the breather with the pcv still intact. Either get rid of the pcv and run two breathers, or eliminate the breather and keep the pcv.

redsn95gt · Dec 28, 2011

95opal said:
Your problem is with running the breather with the pcv still intact. Either get rid of the pcv and run two breathers, or eliminate the breather and keep the pcv.

Thanks- makes sense now. I was half and half so that was probably it. Going to try PCV only with new air line from valve cover to intake tube as it was stock. Replaced breather with the hose outlet type.

Rick 91GT · Jan 2, 2012

Here's a breather tank set-up I just did on a customers 94...it is boosted, no PCV

redsn95gt · Jan 2, 2012

Rick 91GT said:
Here's a breather tank set-up I just did on a customers 94...it is boosted, no PCV

Hey, that's pretty slick! So just loops from the valve cover to tank to the upper manifold or lower?

Rick 91GT · Jan 3, 2012

Yes the line coming around the backside of the motor is in the rear of the passenger valve cover....

Thanks for the compliments.... The hardest part is trying to get the breather as high as possible so it doesnt naturally pull oil. A lot of times if the engine bay isnt open I end up making the can itself just for clearance. This one I was able to start with a Stefs and weld in a additional bung.

Ive thought about putting a few kits together to sell, or a design your own kit...you tell me what length lines and I'll fab it all up.

**Noticed you can see the little alt mount I fabbed up as well, car has no a/c or p/s and a Vortech and I hate the Vortech alt placement so I had to come up with something.

VibrantRedGT · Jan 3, 2012

Rick, that's a cool looking set up. I don't think I've seen the alternator on that side of the car ever either.

Rick 91GT · Jan 3, 2012

Thanks, I made templates, the bracket and alternator are being powdercoated black as we speak....

Its amazing how much trouble it is to move accessories and maintain belt wrap

FastDriver · Jan 16, 2012

Looks good, Rick. I think that my breather leaks all over the place and might need you to fab something up for me, too. I don't believe in deleting the PCV system, though. Unless, you can make me see how that would be advantageous in any way, I don't think I'd go that route. Where is the line in the back going? Into the crank case where the PCV system normally runs?

BlackVert · Jan 16, 2012

Rick 91GT said:
Here's a breather tank set-up I just did on a customers 94...it is boosted, no PCV

sorry, i'm confused about this (i can be kinda dense sometimes) ...

is the "catch can" an oil separator? is it just connecting the 2 valve covers to the catch can? is there no manifold vacuum applied?

i'm thinking about a setup like that for my fairlane.

Rick 91GT · Jan 16, 2012

no vac, just lines from the valve cover to the catch can, NO PCV.

BlackVert · Jan 16, 2012

sorry, a couple other questions ....

is the catch can an oil separator? or what does the can catch?
how does air flow through that system? is the catch can vented?
how effective is that kind of setup for alleviating crankcase pressure buildup?

as i said, i can be kinda dense sometimes ...

Rick 91GT · Jan 16, 2012

BlackVert said:
sorry, a couple other questions ....

is the catch can an oil separator? or what does the can catch?
how does air flow through that system? is the catch can vented?
how effective is that kind of setup for alleviating crankcase pressure buildup?

as i said, i can be kinda dense sometimes ...

The catch can is just a "open body", purely to catch any oil mist/vapor and condensation, most have drains located on the bottom.
The can has a vented breather, so the pressure travels through the -10 or -12 lines to the can, and vents (NO PCV)
I find this to be HIGHLY effective at times, depending on the combo. The PCV is effective is working, sometime I find it just isnt enough, and this usually alievates all the pressure.

Scott, aka Raceaholic is doing a tank in line with a line from the PCV, Im intrested to see how that works.

Extra breather necessary?

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I was uncomfortably high & wearing a helmet

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