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Old 12-17-2009, 07:20 PM   #1
Old Yeller 1970
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Need a better PCV breather, I think.

I'm still working the kinks out of the engine in the sig. Today I finally realized what's been causing my oil leaks. With two 3/4" bottom vented Specter/Mr Gasket breathers installed one in each valve cover, oil starts to bubble out between the head and intake manifold once the RPM's get above idle. When I pull the breathers out, the oil stops leaking.

I'm guessing this means I need something a little more performance oriented. What kind of breather should I install that will work correctly?
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Old 12-17-2009, 07:45 PM   #2
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Re: Need a better PCV breather, I think.

Those breathers should be sufficient. It sounds like crankcase pressure is coming from somewhere it shouldn't.
To have oil coming out between the head and intake sounds like a bigger problem. Have you pulled your plugs since this problem came up? Do you have the correct intake gasket installed. One that was recommended by the head manufacture or the intake man.?
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Old 12-17-2009, 08:27 PM   #3
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Re: Need a better PCV breather, I think.

I have Fel-Pro intake gaskets, I think they're the ones Edelbrock calls for. I've had the plugs out many times.
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Old 12-17-2009, 09:56 PM   #4
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Re: Need a better PCV breather, I think.

you need a pcv valve otherwise pressure will keep building. its normal to build crankcase pressure the pcv evacuates it. pcv in one side breather in the other
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Old 12-17-2009, 10:43 PM   #5
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Re: Need a better PCV breather, I think.

It is normal to build crankcase pressure but to push oil out of the intake/head seal?


Have you retorqued your intake since you started the engine? The intake and exhaust manifold/headers bolts always need to be retorqued.
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Old 12-17-2009, 11:11 PM   #6
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Re: Need a better PCV breather, I think.

Did you put thread sealer on intake manifold bolts? without a PCV it whould push the oil past the threads faster.
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Old 12-17-2009, 11:18 PM   #7
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Re: Need a better PCV breather, I think.

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you need a pcv valve otherwise pressure will keep building. its normal to build crankcase pressure the pcv evacuates it. pcv in one side breather in the other
So how do I plumb it? Do I Tee it into the brake booster line?

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Have you retorqued your intake since you started the engine?
Yes

Quote:
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Did you put thread sealer on intake manifold bolts?
Yes
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Old 12-17-2009, 11:46 PM   #8
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Re: Need a better PCV breather, I think.

The PCV valve needs its own vacuum source, On my 70 (i also have a holley)
i have the PCV hooked to the carb, booster is hooked to the manifold (#8 intake port) heres some PCV info

Combustion engines produce varying amounts of blow-by gases--gases containing undesirable pollutants which seep past the piston rings and into the crankcase during combustion.

SYSTEM OPERATION
The PCV system prevents blow-by gasses from entering the atmosphere by routing blow-by gases into the intake manifold through a vacuum controlled ventilating valve and a hose while allowing proper crankcase ventilation.


Blow-by gases mix with the air/fuel mixture and are burned during combustion.
When the engine is running, fresh air is drawn into the crankcase through a tube or hose connected to the air cleaner housing.
When the engine is off , the spring holds the needle valve closed to stop vapors from entering the intake manifold.

When the engine is running, manifold vacuum unseats the needle valve--allowing crankcase vapors to enter the intake manifold.

In case of a backfire in the intake manifold , the valve closes--stopping the backflow and preventing ignition of fumes in the crankcase.

During certain engine conditions more blow-by gases are created than the ventilator valve can handle. The excess is returned through the air intake tube to the air cleaner and carburetor where it is burned in the engine.
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Last edited by clinebarger; 12-17-2009 at 11:47 PM.
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Old 12-19-2009, 02:35 PM   #9
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Re: Need a better PCV breather, I think.

never tee off the brake booster for anything. you will end up with brakes that dont work right. can you take any pictures of where its leaking from?
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Old 12-22-2009, 12:34 AM   #10
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Re: Need a better PCV breather, I think.

mine was pouring oil out of the balancer seal and dipstick tube at about 5 grand
i changed breathers and it works great now
i hope you get yours figured out
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Old 12-22-2009, 01:35 AM   #11
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Re: Need a better PCV breather, I think.

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mine was pouring oil out of the balancer seal and dipstick tube at about 5 grand
i changed breathers and it works great now
i hope you get yours figured out
Mine starts doing it around 2-3K RPMs. Today would have been a beautiful day to get it fixed. Temps were in the mid 60's. But instead I worked on my wife's 38 Special getting the trigger set up for her and then tonight I went with my kid brother to see "Dances with Giant Smurfs" in 3D. If you don't mind the anti-capitalist, anti-military, Gaea-pantheistic-earth worshiping themes the visuals are well worth seeing on the big screen.

Maybe I'll get the PCV done tomorrow.
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Old 12-22-2009, 01:38 AM   #12
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Re: Need a better PCV breather, I think.

wheres crosby county
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Old 12-22-2009, 01:43 AM   #13
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Re: Need a better PCV breather, I think.

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wheres crosby county
I ate supper at the Italian restaurant on the square in Eastland about two months ago on my way to Waco. Pretty good chow.

Crosby County is the next county east of Lubbock on Hwy 82. I live about 5 mi southeast of Ralls.
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Old 12-22-2009, 01:40 AM   #14
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Re: Need a better PCV breather, I think.

Hmmm, I just talked about "anti-capitalist, anti-military, Gaea-pantheistic-earth worshiping themes" in my 666th post. There's a little bit of irony in that.
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Old 12-22-2009, 01:42 AM   #15
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Re: Need a better PCV breather, I think.

yeah just a little bit
im scared for you now
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Old 12-22-2009, 01:46 AM   #16
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Re: Need a better PCV breather, I think.

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yeah just a little bit
im scared for you now
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Old 12-22-2009, 01:46 AM   #17
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Re: Need a better PCV breather, I think.

was the resteraunt called salvatores

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Old 12-22-2009, 02:17 AM   #18
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Re: Need a better PCV breather, I think.

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was the resteraunt called salvatores
Indeed it was.
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Old 12-22-2009, 02:18 AM   #19
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Re: Need a better PCV breather, I think.

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they have some good pizza
well if you come through again you should come by
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Old 12-22-2009, 02:22 AM   #20
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Re: Need a better PCV breather, I think.

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they have some good pizza
well if you come through again you should come by
Will do.
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Old 01-02-2010, 02:17 AM   #21
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Re: Need a better PCV breather, I think.

Hey all, I finally got the PCV valve installed today. And PRESTO, no oil leaks. I didn't get it done sooner because it's been pretty cold ever since the blizzard Christmas day. I still didn't take it out for a spin because our gravel driveway is still a muddy mess while all the snow drifts continue to melt off. I did let it idle for several minutes at 2-3k RPM's and am satisfied that this part of the puzzle is finished.
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Old 01-02-2010, 02:47 AM   #22
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Re: Need a better PCV breather, I think.

good deal knew the pcv would get ya fixed up
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