SilverRocket

Alright this is for all you crazy ***** who have also yanked the emissions....

I think I have everything hooked up right, and yet I still get the dreaded condensation/slime inside my oil filler neck. This is causing the neck to rust inside, and quickly I might add. WTF??

First of all my car is a 1982 model. This means that the lines from my charcoal canister do NOT go to a "vent and check valve" but straight to the gas tank, and also to the crankcase hole underneath the oil filler tube. I had a "purge valve" which connected to the oil filler neck but not anymore.

Here's the pertinent facts:

- I have junked the whole nest, including the purge valve
- I have kept the charcoal canister and associated lines intact
- I have run a line from the oil filler neck to the "air vent solenoid" port on the carb (I believe this is what it's called), as a much-smarter-than-myself rotorhead showed me to do.

So, I know that the purpose of the line I have run is to dump the fuel vapors into the carb to be burned. But why is this apparently not happening?? Do I need that purge valve in place, and a source of vaccuum, to suck the fumes out?

Do I need to reconnect my purge valve? If so, how do I do it since my rat's nest is gone?

I have read everything on Mazspeed regarding this, and have not got any real answer out of it. I'm hoping you guys can sort me out.

Thanks in advance!!

Jeff20B

iTrader: (13)

Heh, it's so stale here, isn't it.

Anyway, do you suspect that your engine may be leaking a little coolant into the oil? I checked out an engine that ran for a while that had no rust in the filler tube. Then just last night there was one that had lost of water droplets all over the inside of the cap. It looked like the lid on a pot of boiling water. We emidiatly changed the oil and hooked up a tube from the neck to the air filter. It's the only thing we could do because that engine has an aftermarket intake. I hope my friend's engine is ok.

Lastly, I don't have a 12A and I don't know anyone personaly who does, so I can't really help you. Good luck with it though.

SilverRocket

It is 4 in the morning on a sunday though....

I don't think there are any leaks or anything like that... this is actually a really common problem associated with removing the emissions nest.

I suspect the answer is to reconnect the purge valve somehow, but I'd like to hear from others who have overcome this same issue. I had a perfect clean filler neck a month ago and now it's all rusty

RXcetera

SILVER!!! What did I tell you? RELAX!! lol. Most RX7s have "oil foam in the filler neck", especialy the ones driven at 7000rpm all day. My car does this too, and my purge valve is hooked up. As far as running a line from the filler neck to the air vent solenoid... are you sure that's how we did it? That just doesnt sound right to me... I might be wrong though. I'll check the shop manual tonight and let you know.

As far as the rust goes, I've seen many cases (including my car) of a fine layer of rust forming inside the neck, but I have never seen one that has "rusted out". As usual, I recomend you "dont worry about it!, relax and have some fun!" lol.

mazdaspeed7

If the oil neck vent is open, it wont foam. Put a breather filter on it, or run a line to the air filter.

Jeff20B

iTrader: (13)

Mine has had a line from the filler neck nipple tube type thing over to the vacuum operated thing on the intake manifold on my pre '79 13Bs. I have zero rust and it's been like this since '96.

My friend's 13B neck is so rusty that pieces have fallen down into the pan. Yes, it is almost rusted through! I cleaned out all the rust chips on the filler cap threads and tryed to screw it back on the filler neck. It won't sit on it tight anymore. Too much metal has rusted away. I just tightened it untill it almost slipped the threads, then backed off slightly. It should be tight enough. I hope. I also ran a rubber hose from the nipple to the vacuum operated thing on the intake manifold. It should prevent any new rust, but the damage is already done.

Does anyone know the name of the vacuum operated valve tyoe thing on the intake manifold? Better yet, I'll just look it up in my manual.

Oh yeah, my friend's filler tube was open to the atmosphere and it rusted badly. Not even a filter on it will help. (the filter will most likely slow the air escaping)

peejay

you can't run just one line. you have to run BOTH lines so there is airflow through the inside of the engine.

Run a line from the clean-air side of the air cleaner, directly to the nipple on the center housing - NOT the one on the filler neck!

Now run a line from the intake manifold to the filler neck, and splice a PCV valve in this line. I used a common one that many Mitsubishi engines use (try, say, '92 Caravan with the 3.0l engine, as a specific example if you need one) because they are easy to tell the engine end from the other and both sides are fairly easy to stuff into a vacuum hose. The threaded end is the one that goes towards the intake manifold.

Now what happens is, fresh air is flowing through the engine, from the air cleaner to the center housing (where the main oil drainback, and most of the internal cavity, are) through down to the bottom of the engine up the filler neck through the PCV hose and into the intake. Without the constant fresh airflow the condensation WILL build up.

Oh, and if you get the two lines mixed up at the center housing, the engine vacuum will suck on all the direct oily mist from the inside of the center housing, which can get spectacular.

SilverRocket

Thanks Peejay, that's the advice I was looking for...

BUT.... There is already a line from the canister to the center housing, so I can't just hook the center housing up to the air cleaner.

And I can't really eliminate the charcoal canister, cause then what do I do with the line coming from the fuel tank?

It seems to me that I should run some kind of T-fitting in order to add a line to the aircleaner.... Am I missing something?

Rxcetera - I know I should calm down and take 'er ez.... but I really want to fix this problem. This is for sure a new development, and if it can be fixed I want to do it. So there!!!!

peejay

Yeah, you could run a T-fitting, if you want.

I just left the fuel vapor hose dangling off of the firewall.
Doesn't really get "fumey" under the hood, so it's not like all the gas is evaporating out of the tank. And besides, the car is the EPA's worst nightmare as it is...

peejay

DUH... just realized... the way the system works is that it sucks the vapors out of the fuel tank, through to the charcoal canister, which stores the vapors when the engine's not running. When you start it the purge solenoid dealy purges the vapors from the canister through the engine. So what's probably happening is, somewhere along the way, something isn't happening right.

What I'd try, though, is running the center plate to the air cleaner, and take the canister out of the equation. Probably wouldn't hurt to leave the vapor line hooked to the canister, but it also wouldn't hurt to leave it dangling either.

SilverRocket

What if I set up a T-fitting at the center plate, attached to both the air filter and the charcoal canister. Then I run the oil filler line to the intake manifold. That way both systems are doing what they're supposed to ( I think...)

Oh yeah... can you explain to me the purpose of the PCV valve? I don't know what PCV stands for, but I assume it's some kinda one way check valve? Would it be dumb to set it up without this?

Thanks for all the help Peejay, you tha man

peejay

Well, I'm still kinda fuzzy on exactly how the PCV works, I forgot all that stuff from high school autos class (read: first thing in the morning and nobody paid attention anyway).

Basically, yeah it's a spring loaded check valve. Without it you'll have a largish vacuum leak, albeit a vacuum leak that also sucks the vapors from the inside of the engine. But a vacuum leak all the same and it'll run like ****. Tried it already...

They make in-line PCV valves, but I'm fuzzy as to which direction thei're supposed to go in, so I just go with the Mitsu type and remember that they thread into the intake manifold so the threads go on the vacuum side of the hose! Hey it works... and no more lungmustard all over the dipstick and in the filler tube.

SilverRocket

I have one more dumbass question - when you say to run the line to the intake manifold, do you mean the nipple directly underneath the shutter valve crap? Right now I have it running to the big vacuum nipple at the top of the carb.

Thanks Again.

Sweet, a trip to Canadian Tire and I'll have this all set up

Pele

iTrader: (28)

PCV = Positive Crankcase Ventalation

On a boinger, the gasses in the cylinder on compression sometimes leak back around the piston rings. This is blow by and it degrades the oil and pollutes the atmosphere. So they allow fresh air in somewhere and sucks the vapors out into the engine to be burned in combustion.

In the rotary, the rings are partially equivalent to the oil control rings. So your mixture and some fresh air get into the oil. It needs to be sucked out, or it will degrade the oil (Defenately not good on a rotary.), pollute, and cause condensation.

peejay

Oh! There's your problem.

That's not a vacuum nipple, at least if you're talking about what I think you're talking about, it's not. Start the engine and pull the hose off of it... does it have a vacuum? I think what you're talking about is the carb bowl vent.

I found an unused, correctly-sized vacuum nipple on the manifold itself, above the rear rotor.
should work... the vacuum hose on the left is about where i tapped off of. The disconnected one on the right is an oil line. (Yes, my headers have turned purple, and yes that is a total mass of JB Weld in the manifold... )

Sterling

The condensation is a natural by-product of gasoline combustion. Like Pele says, it gets into the oil from exhaust blow-by.
The purge valve goes from the vacuum source on the carb to the crank. But if you don't have another opening for fresh air entry, there will be no flow to carry away the water vapor and other nasties. So that's why the nipple on the filler spout. That gets hooked to the charcoal canister.
The canister is just a box o' rocks that provides alot of surface area for fuel vapor from the tank to collect onto when the fuel expands from heat. There's a valve inside, and a nipple at the bottom (84-85) for the tank to contract (prevent vapor lock, scince the rest of the system is trying to suck out the vapors). This bypass valve has no effect on allowing more air into the purge system.
The oil spout filler goes to the box 'o rocks, and then to the top of the carb. This is your fresh air source.
So the purge valve is keeping the crank case free of water vapor, and they 'kill two birds with one stone' by having it suck out the canister, too.
It is'nt set up so that the water vapor from the crank goes through the canister because that would just make a slurry of crap in there.
They get all they need, and all this combined with a valve that closes off the whole system (float bowl solenoid) when the car's off.
Poof...No emissions leaks. It all get's burned.

And speaking of leaks, well your whole carburetor is one controlled leak! So don't be concerned with the purge valve "leak" in your carb system. It's a constant, not a variable, and the carb simply is tuned to compensate....That is, if there's anything to compensate for - Afterall, there's an awful lot of fuel vapor from your gas tank in that "leak".

"Of course, that's just my opinion- I could be wrong."

SilverRocket

Alright I think I fixed the problem...

Peejay you were right, I had it hooked up to the carb vent, no vacuum at all.

So all I did was hook up the oil filler neck to the aforementioned intake manifold nipple underneath the shutter valve arm (over the rear rotor). That yielded lots of vacuum. I left the carb vent open.

So here's how my system works now:

The fuel tank vent goes to the charcoal box o' stones, which in turn goes to the center housing nipple. The oil filler neck goes to the intake manifold. That's all, no air cleaner connections.

It's obvious that things are different now, if I remove my oil cap the engine dies out. I had to readjust my idle speed and mixture quite a bit too, as it was idling way too high and rich.

So what do you guys think? Have I screwed up by not incorporating a fresh air source? Is it bad that my manifold is sucking away at the crankcase and canister and all that? Maybe I should run the air cleaner to the center plate and forget about the charcoal box?

So many questions...

Thanks for all the help, I'm sure others will benefit from this info too.

RXcetera

Silver, I PM'd you on this subject. I suggest you unplug that vaccum line from your oil filler neck before something really bad happens.

Felix Wankel

Drill a small hole in your oil filler cap, and hook it up the way you had it the first time. That, or put a small K&N breather filter on the oil filler tube.

craigw1

i have the small breather filter on the hole on the filler tube and i still get the water droplets on the oil cap wtf ?