Seems like this is a common issue. You oil neck is rusty, you've got water condensing on your oil cap, and you've got some weird yellow/white gunk In your oil fill neck. Is this normal???....NO! You've got crankcase venting issue! Well what do I do? Take charge of the situation, roll up your selves, and get to work.

First task, remove the oil fill neck, so you can get the rust out of it. You dont want that falling down into your engine.

This is quite a task, but have faith. I sprayed some WD-40 at the base of is, where it is pressed into the cast iron. Than I tapped with with a hammer back and forth untill it stared to wiggle. Than clamp a set of vice grips on it, and tap upwardon either side of the vice grips, and it should work it's way out. I removed the plug wires, for more room.




Rust is the enemy!





Now we gotta clean this **** up, so break out the grinder and Dremel (rotary) tool. I also taped some sand paper on the end of a piece of a broom stick, and remed it out.







Now, clean it with some alcohol, I used brake cleaner, and shoot a coat of paint on to 'er. I chose Duplicolor high heat flat black.





For the next step I took kgrays suggestion, and drilled a few holes in the oil cap. Now the moisture can escape, instead of condensing on top.



_Intermission_


I love my RX-7!




_Back to work_

Reinstall it, by placing a piece of wood on top of it, to prevent damage, and wack it in with a hammer or mallet. And instead of rehooking up the line that goes to the purge valve (that isn't doin it's job) I clamped a crankcase breather on it. (I borrowed it from my other car, I need to by another one...a blue one.)



This is the Purge valve.



I tore it out, just for fun, than put it back in. But I plugged the line that used to run to the oil fill neck, but plugged all the other lines into it.



No more rust!



Plug this line



That should do er!

 

I was thinking about doing that myself just last weekend but wasn't sure how the tube was fitted into the block - did pull out or unscrew, as I thought might be the case. And I didn't want to cause new damage fixing something that wasn't really broken, so I decided not to do it.

I don't have the venting issue, things are clean inside the tube, but I'd like to freshen that black paint on the outside to match the rest of the engine bay:







Thanks for blazing the trail Mr. 12A, maybe I'll give it a try next weekend!

 

I just drilled the cap like you did and havent had a problem since!

 

No problem Ray, it's a bit of a pain to get out thou, I almost gave up. It WILL come out thou.

And thats good to hear Latin, now I don't have to worry about weather or not this is gonna work.

Question to you techy guys thou, the line that I plugged, should it be plugged or not?

I took the car for a shot drive, and checked the oil cap when I was done, and there was no water!

 

The nipple on the oil neck is supposed to see a small amount of vacuum. Just hooking up a breather filter isn't good enough to get the water vapor (lung mustard) out. There is nothing to actually pull the saturated air out of the oil neck. The hose that you plugged usually sees vacuum (if I'm not mistaken).

This basically means that the moisture comes out of the oil neck, through the hose, through the rat's nest I think, and then eventually into the carb where it is combusted again. If you want to simplify this setup and eliminate your lung mustard try this...

Oil Neck ------------- PCV valve ------------------ Carb/spacer vacuum nipple

Make sure the PCV vale is situated such that it allows the water vapor to be carried to the carburetor through a vacuum line, and combusted. That is the best way I've found to keep the oil neck dry....

 

Theres a thread about using a PCV valve hooked to manifold vacuum to keep the moisture and the pressure from building up. Thats what I use now.

Not sure of the ramification of having the cap unsealed by drilling the holes. It lets the pressure out but now its not a closed system and more importantly may allow stuff in. Something to think about.

Nice job on how to pull the tube and recondition it though. A lot of folks I'm sure will want to do that now that they see how easy it can be done. Good pics.

 

The above reasons for putting a vacuum on the vent tube are why I reinstalled the stock purge valve, along with and according to Carl's instructions in his rat's nest removal tutorial.

One simple solution would be to just put the purge valve back in like it used to be. Since you still have your rat's nest, this will vent the crank case back to the carb under vacuum, keeping your engine, and our air, cleaner. Of couse you will need to lose those holes in the oil filler cap if you do this. Yet another job for JB weld!

Ray

 

The PCV valve solution works well. My only problem is that there isn't a suitable nipple on the DCD manifold, so I'm running a breather right now. It isn't working nearly as well as I'd like...

I guess I'll have to tap the manifold for an extra fitting.

 

Looks like it turned out good. Now it's time to remove the rats nest... and ditch the beehive! As far as saving our air, how does burning the crankcase gas change into helping the earth? Burning=CO2 production and pollution.

 

Hmm...I may fill the holes, and run a PCV valve...by the way, I just removed my rats nest, so there's plenty of places that I can tap into for vacuum hehe.

Im back to work tommorow thou, so not till the weekend...wait I work most weekends....next day off/afterwork!

 

Fill the holes on your filler cap, or get a new one. They can allow Moisture and Debris to enter, and reduce the vacuum through PCV valve.

 

Use the crankcase breather on the cap. This will not allow debris to enter...

 

"how does burning the crankcase gas change into helping the earth? Burning=CO2 production and pollution"

Good question, but I'll bet it does. Here's my guess. The crankcase gases have all kinds of partially degraded hydrocarbons that are produced by the hot engine while it is running. If these are sent to back to the carb, they will be converted to CO2 by combustion in the engine. If not, they contribute to increased hydrocarbons in the atmosphere. While CO2 in the air is not a good thing, hydrocarbon gases are much worse. That's my guess.

Now, does anyone know the real answer?

 

The Rotary Engineering instructions for the dual DCD's plumbed the line to the rear air filter base. That's the way mine is set up. I still get moisture on the filler cap though.

Would a hole in the intake manifold not be considered an air leak?

 

what if you have an aluminum rotor shaped oil cap? then what?

 

Buy a plastic one from the parts store, or drill your cap out... PCV valve is always an option for you.

 

Alright, first of all I want to say that I appreciate all of the hard work that you have put into this project. We really can use people willing to do this sort of thing, then take lots of pics and write up a tutorial. However....

1. To clean the tube, get a gallon of Muriatic acid from any hardware store. Soak it for about 20 minutes and rinse thoroughly. It will be as clean as the day it came from the factory, no elbow grease needed.

2. I do not recommend drilling holes in the cap. It would seem to me that it would introduce as much moisture into the system as it lets out.

3. In my honest, humble opinion I don't believe that any pcv valve is needed to correct this issue. Its been almost two years since I've solved my problems with the mighty lung mustard, and all I did was run a vacuum line from the nipple on the filler tube to the base of the carb. That's it. Nothing else was needed.

Anyway, this is all just my opinions and experience. And please, don't take this the wrong way. I would really like to see you continue to put forth this kind of effort, it's pretty refreshing.

 

Muriatic acid hooray! I love that ****: its good for anything! another good use for it... cleaning your driveway of nasty oil stains! (but do it at night cause once someone saw me doing it and called the cops because "my entire driveway was foaming!")

 

This how mine is setup also.

 

I wish I had some acid!

Funny you say that, I filled in the holes last night, and ran a vacuum line from off the fill neck to a vacuum, nipple.

 

Been doing it for over 10 years with no problem. And most racers have done the same thing. In addition, where is that mosture going....not in the combustion area but oil pan which in no time will come out again due to heat.

Now, show me your proof.

 

Good info on the oil filler neck, but +1 on the PCV valve suggestion. There's a great little manifold vacuum nipple that doesn't seem to have a purpose on any 1st gen, just south of the shutter valve. I used that with a PCV valve.

The other problem with just drilling holes on the cap is that holes aren't one-way valves, and thus any dust, dirt or grime floating in the air inside your engine bay can presumably find its way into your oil. Not the best thing in the world for sure. If you want an idea of how much stuff floats around, just clean off your carb spacer, drive for a week, then run your finger across it.

Jon

 

I'll have to run a line to one of my air cleaners then. I suppose that the suction from the carbs will have some effect on removing the moisture buildup...

 

Hey, you asked about the oil tube? Check these videos out. In the 15 minute one entitled Basic Rotary Engine Rebuild Parts, Rob shows you how to remove one. I think it's in that video anyway. There are lots to watch; you'll certainly see the procedure in one of them if you watch them all.

http://www.rebuildingrotaryengines.com/