Blocked PCV Hole.... Didn't work

[Speeder2000]

I was under the impression that the hole in the throttle body (per the instructions somewhere on the internet) leads to the side hole in the PCV area and by blocking it, i can vent the PCV to a catch can, etc.

I blocked the hole, and made a hole in the PCV cover (with a future intention of putting in a barb fitting and routing a catch can type device, but aparently the hole on the side of the PCV "hole" in the intake manifold is connected to the plenum and I'm getting vacuum there... So what did I do wrong?

[dmw319]

Re: Blocked PCV Hole.... Didn't work

the pcv is on the top of the intake, not the side. the MAP is whats on the side, and that is where vacuum is. (if im understanding you correctly). all you need to do after blocking the coolant passage on the TB is put a breather cover over where the oil neck is on the passenger side of your motor.. if anything, thats where youd run a catch can setup.. but only if you are running a serious amount of boost you would even need to do that. post a pic of what you did so we can better understand as well.

[Speeder2000]

Re: Blocked PCV Hole.... Didn't work

i'm at work right now.

I am planning on running a good amount of boost.... with a Garrett GT40

Anyway, the PCV hole on the top of the intake manifold has 2 "passages" on the inside. The bottom one where the PCV valve goes into (crank case vent I'm guessing) and a side passage which *i thought* goes to the throttle body before the throttle plate.

I blocked the bottom throttle body hole, now if I take off the PCV cover, pcv, etc, and start the engine, theres vacuum in the side "passage" which I thought would be blocked off...

[dmw319]

Re: Blocked PCV Hole.... Didn't work

you might just be overworking yourself. this is all i have done, as well as others and its been working fine.

1. block off TB passage.
2. vent it by putting a breather on the oil neck.
3. if oil spews out that breather (aka with a lot of boost, this will happen)... then make a catch can setup come out of where that oil neck is.

i never even touched my PCV valve or anything thats on the top of the motor. someone correct me if im wrong, but i dont even think you need to do anything with it.

[Speeder2000]

Re: Blocked PCV Hole.... Didn't work

Possibly - I was trying to keep the PCV functional and not use a breather. Here is essentially what I was trying to do
http://picasaweb.google.com/cooneym63/Pcv

except instead of using the hose, I thought that by blocking the throttle body hole, the side hole is blocked and all is good.

[Shodown]

Re: Blocked PCV Hole.... Didn't work

you might just be overworking yourself. this is all i have done, as well as others and its been working fine.

1. block off TB passage.
2. vent it by putting a breather on the oil neck.
3. if oil spews out that breather (aka with a lot of boost, this will happen)... then make a catch can setup come out of where that oil neck is.

Yep.

i never even touched my PCV valve or anything thats on the top of the motor. someone correct me if im wrong, but i dont even think you need to do anything with it.

I didnt remove mine either. Just blocked the TB and drilled holes to vent it. I'll try to get some pics tonight.

[ssms5411]

Re: Blocked PCV Hole.... Didn't work

If you blocked that pcv in the TB and left your oil cap on without putting on a breather, you will start popping out gasket seals, either valve covers or head gaskets. The air will go out somewhere without a breather on there.

[Speeder2000]

Re: Blocked PCV Hole.... Didn't work

Yep.



I didnt remove mine either. Just blocked the TB and drilled holes to vent it. I'll try to get some pics tonight.

Thats kinda what I was going after... are the holes you drill alongside the tb go between the tb hole, and the side passage in the PCV valve area?

[Speeder2000]

Re: Blocked PCV Hole.... Didn't work

Here's a PCV hole diagram

Assuming that I block the TB hole, why is there vacuum in the side passage? Is the tb hole not directly connected to the TB passage?

[ssms5411]

Re: Blocked PCV Hole.... Didn't work

There is vacuum because the engine needs to vent its pressure if not it is going through your seals.

[Speeder2000]

Re: Blocked PCV Hole.... Didn't work

whats the TB hole connect to then? The bottom part?

I'm just confused now. In the PCV hole, where does the side port go, and where does the bottom port go?

[ssms5411]

Re: Blocked PCV Hole.... Didn't work

Normally the PCV vents from the engine up through the upper intake into the TB and vents back though the TB into the upper intake and down to the lower. By blocking the TB and putting a breather on the oil cap it just goes out the breather and not back into the engine. The side of the upper intake where the PCV valve is the torx head bolt on the side should be left alone. Just putting a plug in the TB and putting on the breather on ther oil filler cap should be fine.

[dmw319]

Re: Blocked PCV Hole.... Didn't work

^^ yep. what he said :)

[FirebirdGT]

Re: Blocked PCV Hole.... Didn't work

Here's a PCV hole diagram

Assuming that I block the TB hole, why is there vacuum in the side passage? Is the tb hole not directly connected to the TB passage?

WRONG!!

The hole in the TB goes into the casting wall of the UIM and down through the LIM into the crankcase to provide filtered fresh air to the crankcase. When the pressure inside the crankcase increases, another vent line connects to the spring loaded PCV valve which opens and vents the oily air into the UIM. That is how a POSITIVE CRANKCASE VENTILATION system works.

Take it apart and you will see.

[ssms5411]

Re: Blocked PCV Hole.... Didn't work

Rob, the Torx bolt there does nothing, the best thing for him to do is like we described. Many have done it this way and it is easy to do without messing it up , the oil cap breather provides more than enough of venting and adding freash air. With beginners this method will work unless he is running over 20 lbs of boost. I was trying to give him the easiest way to do this like everyone else running boost has done it. Hell I even kept mine block, since I don't want nitrous shooting up there.