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Hey guys, I have a question. over the weekend I drove my car around 100 miles with 0 issues ( except going up a really steep hill, the temp rose from its normal 25-30% to 50% during the 10 min drive up, went right back down to 30% once I drove downhill ) . When I got home I noticed there were small amounts of oil that had leaked out of the nipple pipe that sticks out of the oil pipe where you pour oil in. The nipple is open after removing my stock emissions system as I was told NOT to close it by two rotary guys I know as it " keeps condensation out of the engine" this is the second time oil leaks out of there. I want to make it clear, it is NOT a large oil leak, it is small drops. I have no emissions system so I have no idea what that tube went to before, or if I should seal it with a rubber cap. The second time it spills from there (the other time was when I drove up and down hills In east LA. ). I did a full inspection to make sure THAT was the source, and sure enough, it was. If I cant seal it, would an L shape pipe help avoid minor spills?
While leaving it open is definitely better than capping it condensation-wise, the engine will probably still produce condensation in the oil filler neck. Originally, the factory system goes through some stuff in the rat's nest and ultimately ends up at the same place I have mine.
Mine is just run directly to the nipple on the top of the factory air box. Mine has no emissions equipment, as well. No issues, really. You don't want the port to see a strong vacuum, of course, because it may start to drink your oil, but the gentle pulling from the carb below what I believe to be what is called a charcoal canister, gets the job done perfectly. Or they wouldn't have done it factory.
But you could also make or buy a catch can and run a hose from the nipple to the can, and check on it every so often to make sure it doesn't fill up too much if you'd rather.
While leaving it open is definitely better than capping it condensation-wise, the engine will probably still produce condensation in the oil filler neck. Originally, the factory system goes through some stuff in the rat's nest and ultimately ends up at the same place I have mine.
Mine is just run directly to the nipple on the top of the factory air box. Mine has no emissions equipment, as well. No issues, really. You don't want the port to see a strong vacuum, of course, because it may start to drink your oil, but the gentle pulling from the carb below what I believe to be what is called a charcoal canister, gets the job done perfectly. Or they wouldn't have done it factory.
But you could also make or buy a catch can and run a hose from the nipple to the can, and check on it every so often to make sure it doesn't fill up too much if you'd rather.
Seems like a good idea. I think the steep hill helped the oil vibrate its way up there.
Okay, here's a rundown on the charcoal canister and the PCV systems, and how they relate. I am experienced with FB's only, which have the charcoal can on the right fender. SA's keep the charcoal inside the air filter lid. I'll talk about the rubber line routing on FB's.
Charcoal Canister -
The gas tank needs to "breathe" and does this through a metal hard line from the tank to the firewall. From the firewall it becomes a rubber line to the charcoal can.
When the gas warms up and evaporates/expands it breathes out to the charcoal can. The charcoal holds the gas vapors so they can't escape to atmosphere and don't stink up your engine bay/garage. When you start the car those fumes are sucked into the engine and burnt. When the motor is running and pulling fuel from the tank, that vent line let's air flow the other way into the tank, so you don't get a vacuum condition in the tank which would fight against the fuel pump. When guys complain that removing the gas cap either let's a big burp out, or sucks air in, it's because their vent line is plugged, clogged or crushed. This can also make you run out of fuel after a few miles.
Engine Block Vent (aka PCV) -
All auto engines have some kind of PCV system to suck vapors out of the engine block. These are usually gas vapors pushed from the combustion chamber into the open areas or oil pan area of the engine (rotary, piston, doesn't matter). It could also be water vapor or vapors from hot oil.
The nipple on your oil fill tube is for venting the engine. On FB's there are 2 nipples on the charcoal can and 2 nipples at the base of the oil fill tube.... one on the tube and one in the center iron right near the fill tube. As explained above, there's a vent line from tank to charcoal can, then one from charcoal to the lower nipple on the block, then the upper oil tube nipple through the rat's nest to the carb. When you start the car it sucks through those lines, taking all the vapors from the block and all the vapors trapped in the can.
So, you should have a line on the lower block tube to let air in, (from charcoal can on FB's) and a line from the upper tube to the air cleaner so air is circulating through the lower engine. If not you will see "lung butter" build up in the oil fill tube and presumably in the motor. This is oil mixed with fuel and water vapor and looks like pasty yellow snot.
I don't remember if you have the rat's nest, a nikki, or what. On a stock engine the rat's nest controls when all these vapors are purged. On a stripped engine just run that upper tube nipple to the air cleaner. I don't know if SA's have the lower tube.... mine is connected to the charcoal can like stock and both these systems work fine, without the rat's nest.
SA owner here. I have mine routed from the gas tank vent to the oil filler nipple then from the other nipple to a charcoal canister from an FB then to the carb.
Yeti I don't think your charcoal can is serving any purpose if that's how it's routed. The can is to catch gas vapors as they leave the gas tank (car off, on a hot day) and hold them until the next time you start it up. Your setup is just dumping those vapors directly into the block.
Yeah my SA is the reverse of Yetis. I have the tank vent line to the nipple on the center iron and the nipple on the oil tube goes into a small inline PCV valve and then into the bottom of the air cleaner (nonstock air cleaner). Works perfect.
Ok, I may have described it wrong, I haven't really thought of / looked at it in a while. I'll verify later but reading t g farrell's description that is what I was attempting to describe. Sorry for misleading anyone.
I do have a question because I don't recall a difference. What is the difference between "the nipple on the center iron and the nipple on the oil tube " Isn't that going to the same place, the oil pan?
MaxWedge, after installing the charcoal canister the fuel smell went away so I think it's working.. I'll investigate again.
The nipple on the iron is internally routed deeper into the motor, down by the pan. The air flows in and down, before being sucked up and out through the tube nipple. That way it removes more vapors from the engine. The nipples look like they're only 2" apart but the air moved is much more.
So, as said the FB's charcoal can has 2 ports (nipples) on it. The gas tank fumes on a hot summer day flow into it and are trapped, and upon startup they are sucked through the other hose through the engine and into the intake (air filter, carb, rat's nest,.. whatever). The charcoal can is open on the bottom to allow free flow of air...
This let's the gas tank pull air as you draw fuel from it, so you don't get vacuum-locked and cut off fuel to the fuel pump. It also let's filtered air (see the filter in there?) flow the other way through the block into the carb/air cleaner to purge the vapors out of your oil pan. Fuel and water vapor compromise your oil.
When the car is off, it's a vapor trap. When the car is running its a filter and allows air flow in both directions. I don't have any emissions testing to deal with but F emissions, I have it semi-stock so -
1) My tank can breath and fuel can flow
2) My engine can vent the vapors that cause oil to break down and form snotty lung butter inside the engine..
These simple systems have been used since the 50-60's, long before emissions was a big deal. It's just good for your car and doesn't cost you a single hp.
There should be the nipple that is part of the oil tube, and another pressed-in nipple in the center iron. If yours got lost atkins has them -
'74-91 RX7 Center Iron Breather Tube part # 8562-10-417
Never mind I re-read again and finally saw the difference and you are right. The way I have it, while maybe doesn't hurt anything, isn't correct. I must have misread/misunderstood documentation somewhere. Now to find or buy more vacuum hose.
The way I have mine routed now is: tank vent > oil filler neck > center iron > charcoal can > carb. The way I understand it should be is: tank vent > charcoal can > center iron > oil filler neck > carb.
When I bought the car it was not setup at all and I had "lung butter" which is now gone so I had no reason to doubt my route. A lot on this car was set up... differently...
To add to the conversation, does it matter if I have it routed to the manifold or the filter area?
I have a weber so currently it's on the manifold but there is one port on the underside of the filter. I assumed the vacuum in the filter area would be negligible at best and I'd be better off connecting it at the manifold.
To the OP, sorry I have stepped all over your thread, hopefully my ignorance will help you and others with questions you didn't even have yet. Also, thank you for the question as I would be ignorant otherwise without it.
Yeti,
I think your setup / routing will work for venting the tank and the engine. But the charcoal can isn't really doing anything except being a pass through. If you re-route your hoses you can make it the only thing the tank vent sees when breathing in or out (as designed). And when it purges the can and crankcase it is pulling through a filter media in the bottom of the can.
EDIT - Actually I don't think it is working as well as it should for venting your block. You said it got rid of the lung butter, which is good. But as the intake is pulling from the block it's also getting clean air through the bottom of the charcoal can. It's like having a big cut in a vacuum line.
Yeti,
I think your setup / routing will work for venting the tank and the engine. But the charcoal can isn't really doing anything except being a pass through. If you re-route your hoses you can make it the only thing the tank vent sees when breathing in or out (as designed). And when it purges the can and crankcase it is pulling through a filter media in the bottom of the can.
EDIT - Actually I don't think it is working as well as it should for venting your block. You said it got rid of the lung butter, which is good. But as the intake is pulling from the block it's also getting clean air through the bottom of the charcoal can. It's like having a big cut in a vacuum line.
It seems my mechanic sealed that hole with a screw..
UPDATE! So I sealed the nipple off with a plug.. NOT GOOD. The car was having issues shifting, it kept thinking it was in neutral and having issues going from 2nd to 3rd. I figured my trans was acting up because I topped it off last week as i was running it at half full on the dipstick, i was checking for leaks, and it worked fine, but the switch from 1's to 2nd was noticable after I topped it off it was seamless but revved a bit higher, turns out I overfilled it about a tenth of an inch too much on the dipstick. so I assumed " oh crap this is getting worst" I drained about 7 ounces, checked the dipstick, it was right under full. I drove it and the issue kept getting worst, Went to go check the trans again and my oil dipstick had popped out and there was oil leaking at the nipple. I took the plug out and there was a gush of air that came out like when you release a balloon, turns out the engine was building air pressure due to the heat, I made a channel in the rubber and popped it back in . Trans issues went away. So I discovered that that little vent has SOMETHING to do with the transmission and engine. At least in an automatic. Who would have known.. and yes it was that the car didn't do that issue, and it had only been doing it since I plugged the hole.
Any theories as to why that nipple makes my car have trouble shifting when not vented properly haha, the little rubber plug now lets it breathe but is small enough so the oil doesn't leak out anymore btw.
The rush of air is because the blow-by (compression pushing past the rotor seals into the "crank case") is building pressure in your engine. That's why those nipples are supposed to be vented... to purge those gasses/pressure.
No Idea how that would affect the auto trans, which is operated by engine vacuum, load and road speed inputs. I think it's a coincidence.
The rush of air is because the blow-by (compression pushing past the rotor seals into the "crank case") is building pressure in your engine. That's why those nipples are supposed to be vented... to purge those gasses/pressure.
No Idea how that would affect the auto trans, which is operated by engine vacuum, load and road speed inputs. I think it's a coincidence.
The trans began giving me issues after I plugged the hole . The day before I plugged it i drove 30 ish miles and took some chick out to the movies , no issues. Since I plugged it i have driven it 3 times , issues got worst , today I unpluged it at In n out burger , drive home 0 issues and I tried to induce the issue ( letting it coast to a stop = enter into neutral, up a incline without gas = enter into neutral , 3rd engaging oddly at 30 mph if I had a constant speed) . The only other change I did was bleed my brakes and thats when the issues began but then I remembered I pluged the hole the day before . Also on my car , the hole every one unplugs on their carb floods my carb , the guy who fixed my carb said he only ever see's automatics do that , every other SA is fine with that nipple plugged . Odd little things..
The automatic is told when to shift in part by a vaccum switch which is hooked in somewhere on top of t he engine. I would expect messing with this signal would cause shifting issues. The FSM talks a little about the auto and may show you where this is at.
The automatic is told when to shift in part by a vaccum switch which is hooked in somewhere on top of t he engine. I would expect messing with this signal would cause shifting issues. The FSM talks a little about the auto and may show you where this is at.
No idea, but it was def the nipple, no issues today at all
04-19-21, 03:39 PM
