CarlRx7

to all guys/girls that have a wrap around side draft manifold. i have found a nice pcv valve at autozone.

its a deutsch part pcv145. there are two threaded holes in the intake manifold. the one on the right is 1/8" NPT. the PCV valve i mention just screws right in with a lil teflon tape. then add a 1/4" or 5/16 hose ( i used 1/4" becuase it was a tighter fit) and plumb it to the port on the filler tube.

i will post some pics of it later.

i was starting to get the rusted filler tube syndrom. and my oil was being diluted with gas.

carl.

RX7145

iTrader: (1)

I would like to see pictures as well as a small write up.

Hades12

Sounds good. Thanks

DAVID GRIMES

That sounds cool, Carl. Thanks for sharing.

So the vacuum from the intake manifold will suck the crap out of the filler tube and burn it in the engine ?

Sounds like the only downside is I won't be able to add oil while my engine is running. LOL I can deal with that !!!

DAVID GRIMES

BUMP ONE

for carl's pics, please

vipernicus42

iTrader: (4)

Wow... here's a newb question for you guys:

What exactly is a PCV Valve, and what does it do?

I know it stands for "Positive Crankcase Ventilation"... so between that and the "I can't fill my car with oil while it's running" comment I figure it has something to do with venting the crankcase! But why the crankcase needs venting with this specific thingy, how it works, and if my 84GS has one are all questions I just don't get.

Having disected my rat's nest, I know that I have a tube going from my oil filler neck, to a purge valve, to my carb. Is this basically meant to "suck" dangerous vapours from the crankcase into the carb?

Jon

Siraniko

iTrader: (13)

I have owned RX for over 20 years with just a plastic nipple mounted in the oil filler cap with no problem. Why care about venting when we dont have any smog crap at all. Why try to recreate the wheel.

Just my $0.02.

Hyper4mance2k

iTrader: (40)

i currently have a k&n on my filler neck and run a hose from the crankcasevent nipple to the charcole canister then from the canister to the gas tank does this work?

Hyper4mance2k

iTrader: (40)

PeeJay has brought this up a few times and there are a few threads on it and some other way to hook it all up, but I havent a clue we need pics i guess...

Pele

iTrader: (28)

No engine has PERFECT compression. Some combustion chamber gasses leak past the side seals (on a rotary) or piston rings (on a boinger)... These gasses consist of either exhaust or gasoline and air...

Neither substance is good for your oil. Gasoline will thin the oil. Thin oil has reduced pressure and also won't protect as well. Exhaust will just dirty up the oil.

So you suck the fumes out of the crank case/oil sump (I hate calling it a crank case on a rotary.) by using the intake vacuum. There is usually a breather to let air into the crank case.

PCV valve stops that from being a huge vacuum leak as well as stops air from going the opposite direction (In from intake manifold, through crank case, through breather, and out to the atmosphere.)

Piston engines usually locate the PCV valve on the valve cover or upper intake manifold.

You wouldn't be able to fill the oil with the engine running (WTF would anyone do that for anyhow?) because the vacuum would jsut suck the oil from the filler tube straight to the intake mainfold... As if you were dumping the oil down the carb.

Hyper4mance2k

iTrader: (40)

dude i need a diagram there are two nipples on the rotary the crank case nipple and the oil filler neck which one are you fu(kin talking about? they both need to be vented. plug either one of them and you get **** in the oil. no point in compiring this to boingers this is a whole different animal. all you need to do on a piston i run from the valve cover to the intake or just simply put on a breather.
now if some1 would take 1-2 minutes to make at least a shitty drawing in paint like i did it would help so much!!
Here it is what do i do with these nipples??

Pele

iTrader: (28)

One is in and one is out... A breather goes on one. The other leads to the PCV valve.

Really doesn't matter which is which... Actually, if you have the rats nest, the crankcase one goes to a solenoid I believe.

Unsupa

iTrader: (2)

but if you put a breather on one and let the other be controlled by vaccum, you still get a big *** vacuum leak. that's why i took the pcv off...

Jeff20B

iTrader: (13)

peejay will probably have a something to say. A '92 Mitsubishi PCV valve is what he recommends because it has nipples on both ends for an inline installation.

CarlRx7

here is the path for the pcv valve install.::

intake manifold - pcv valve - nipple on filler neck - from nipple on "crank case" to tube on firewall that goes to charcoal canister, that goes back to the fuel tank.

carl.

Hyper4mance2k

iTrader: (40)

this topic keeps coming up and noone who has solved the problem has shown pics. I have never seen a pcv valve would some one help out this subject comes up at least once a week and is getting rediculas since there are so many people with the solutin to this problem. After an extensive search this si the best I've found.
https://www.rx7club.com/showthread.p...5&highlight=pcv

DAVID GRIMES

What if I no longer have a charcoal canister or a line going back to the gas tank ? Then what ?

Pele

iTrader: (28)

Then you're driving a fire hazard. That canister absorbs gasoline vapors for later consumption by the engine, rather than letting them collect in other places and around the car.

DAVID GRIMES

Not wanting to appear disrespectful, but ...
I got my fuel tank connected to the red holloy
and it got connected to the NOS regulator
and it got connected to the Mikuni
and what don't burn up in the engine comes out the header
to the cat-less exhaust and muffler to make Rex cologne.

SO tell me about this charcoal filter and gas fume business.

Pele

iTrader: (28)

The charcoal canister has two lines on it... A vacuum line to either a solenoid or the intake, and another line that runs under the car to the TOP of the tank... It has no connection to the liquid fuel lines, and is simply to absorb fumes that collect in the top of the tank when the car is sitting...

I've never seen a car catch on fire due to it's removal or problems with it. Hell. Most of my cars have had the lines disconnected from it at one point or another. (Until I bought the car and reconnected them.) They usually reeked heavily of gasoline.

However, for the peace of mind it provides, I'd leave it there... It weighs what, a pound or two at best?

MountainDew67

I too have been trying to figure out the crank case and filler tube vent tubes. I have a custom vw bug with rotary engine and I have a 18" rubber hose 3/8's of an inch on the crank case and a 5/16 hose on the oil filler tube that is about 5"s long. My car runs great at WOT but surges alot while cruising, unless im keeping revs up around 3500 rpms while driving.

A very experienced,motorcycle mech,car/truck mechanic, little rotary experience mechanic, jet ski mechanic has told me that I have possible vacumn leak or float level problems. He gave me a complete tuturial of why it would surge if bowls are a little to low. He didnt really lean towards vacumn, but he did mention it.

What im trying to do is make sure them vents are correct, and or clean up the engine bay with stuff that is not needed. Im trying to address every last issue with this engines reliability,power, and life before dumping money into the car any further (prostreet trans,interior,paint,suspension,4 wheel disc brakes, etc.)

Heres a picture of the two hoses you guys are talking about, but this doesn't help anyone directly...

http://www.geocities.com/kewda360/rotaryybug.jpg