Trekk

road-draft tube: A pre-emission, control-era device for ventilating the crankcase to the atmosphere; a pipe routed under the chassis at an angle that produces a small vacuum as the vehicle travels forward. Fresh air is drawn in through a mesh filter in the oil filler cap, circulated around inside the crankcase and exhausted through the road-draft tube carrying blowby with it.

Sounds like just adding a pipe that goes down wont do anything unless you add a way for the air to flow in.

But then again your not hooked to a valve cover.

expo1

Correct me if I am wrong but here you have the OEM tube from the intake going into the brake bleeding cup. So doesn't that still suck in the crankcase vapors? True the SS will catch some oil, but the point of the first post was that NO crankcase vapors were being sucked into the intake. Is your mod better?

Razz1

I remember this set up. I have it on my 65.

I don't think we need to drill a hole in the Oil cap as the new designs are different.

Just like the 8, my 94 Buick has a plastic cap with no hole. The Buick uses a PCV valve. Since the valve is one way I don't know how fresh air enters into the crank case.

I don't think we need that hole anymore. Air gets into the crank case just from operating normally. Designs are different nowadays. I don't see any need to drill a hole in the cap.

Besides a filter goes both ways. Breathes in and out as required. My filter is sitting on top out of the way and still no oil mess.

mikeschaefer

Well then how does the air get into the crankcase in stock form? There must be some way if the intake is sucking air out.

Spin9k

Good question...don't have many answers. This is all pi-in-the-sky stuff really isn't it? No one know the true effect these mods have...only what they think they feel or what it might do.

But, one goal stated was to keep oil from the accordian flex tube. This should do it. Another is to keep oil fumes out of the intake. This should help some, hopefully some will consdense out, but as there is still vacuum there, some will get by and be taken in.

I'm concerned that positive evacuation is helpful and needed to eliminate waste gases and I'm doubtful that a tube just hung-low, as it were, will do that esp at slow speeds or certainly not at idle.

So this is a variation, to-be-tested mod, perhaps to be useful, perhaps not. But that's the fun of it, yes? Cheap, easy, and possibly beneficial to the community at large. And I created it based on olddraggers inquisitive nature and thoughts. The collective at work.

LiL BenNy

seems pretyy cool if i had the slightest idea what any of you were talking about lol... car noob... heheh

rxeightr

We are the Borg. Resistance is Futile. Must put this mod on now.

olddragger

iTrader: (3)

crankcase gasses collect through various means. some gasses will actually blow by the rotor seals, some air will be sucked in the oil level tube(heck some new mercedes will not even crank up unless the oil dipstick is properly secured!) On recip engines the crankcase gasses can be a good bit--some mustang owners that are FI have had to placed 3 pcv's valve on! I am not as sure on the rotary. Much less moving parts etc Less seals between combustion and the crankcase etc. I just dont have the facts.
I do know this.
1- some engines have had substancial blow back of oil /etc into the intake acordian tube/filer that has come from this site we speak off. This has happen repeatively. For some reason in those cases there is excessive pressure in the crankcase--possibly oil overfill, lack of seal on the rotors etc.
2- There is not a pcv valve on the 04-05's and the 06 models design was changed
3- some have oil condensation on the dipstick--I know, I know the tsb says etc--and that may be true --but it seems so far that the people who have done this mod have not had any of those reoccurances--now this may reoccur once the weather gets colder--dont know.
4- the engine has a better throttle response-- this is a fact reported by more than one
5- a down draft tube done work--it was used for years--just made a mess of sorts and then emission laws/ designs started in. no it doesnt work at idle-- neither does the intake suction--there is no suction at idle at this site-- take it off and put your finger over it--you wont feel any.
So in summery I put an oil catch can on(dont like messes either) and then I ran a down draft tube from the oil catch can to provide a slight sucion at speed--put a little funnel on the end of the tube and the suction effect will increase. I guess a vacumn gauge could be hooked up to it and the car ran at speed to test the effect.
Those with FI had better start (if they havent already and probaly have) addessing crankcase pressures--not to do so makes for a difficult engine to tune and a shorten life span.
olddragger

Brettus

iTrader: (2)

A bit of a heads up - I think we may be making more of this than is warranted .
Since doing this mod a week or so ago I have done about 500 km . Just out of curiosity I just reversed the hose & let it rest against the aluminium intake . No filter,no valve - no nothing - just an open hose . I can say that there is absolutely no sign of any oil or anything else coming out of the hose.

olddragger

iTrader: (3)

The hose from the oil filler tube is open and resting on the intake? But you capped the air intake fitting --right? There is no suction of any kind acting on the tube? Maybe thats the reason, or maybe you are one of the lucky ones that has never had any blowback into the intake.
i will admit there are a lot of questions, since these cars seem so individualized.
olddragger

Brettus

iTrader: (2)

yes and yes . It is cold here right now so that may have a bearing.

wcs

iTrader: (2)

I've been following this thread with interest and while I do not have anything to add technically I did do this mod and will quickly share my thoughts and experience.

- So I figured a catch can would be the ideal way to do this, however I decided first not to build one and just run a hose down to a suitable area on the frame.
- I just wanted to see if I notice any difference with this mod. If the mod works I would spend more energy to do a complete catch can mod.
- So for a few bucks to buy a few feet of hose you can remove the existing hose saving it to put back on later if you want too.

- Anyways .... the results? I didn't feel any change, nothing, zero, zilch, nodda, zip. However knowing in my heart that nasty hot crank case gasses are not being fed back into my TB makes me feel good. I will likely keep the mod and add a catch can at my leisure.

Thanks everyone, IMO this was a great mod and I would suggest to anyone that they do it. Especially if your the type that just needs the piece of mind of knowing......

Zielritter

Just did this mod this morning. Went down to Autozone and bought one of those tiny Spectre blue breather filters (to match my ground kit). Anyways, it fit like a charm and looks nice as well. When I removed the tube that attached to the accordion I noticed just how much gunk was being recycled into my intake system. I have never noticed any oil on my k&n panel filter, but doing this mod showed me that I was nevertheless getting some kind of unwanted nasty stuff going into my engine.
I plugged the hole in my accordion tube with one of those things you tie two wires together with (I'm drawing a blank right now on such a simple piece of hardware). Anyways, it is tapered and if you turn it backwards you can plug the hole; it fits pretty snugly. Just in case it tries to wriggle out I secured it a little more by wrapping it with electrical tape. Hopefully it doesn't get sucked into my engine although I'm pretty sure there isn't enough suction to pull something this thick through the hole.
Anyways, unless I'm just entirely too gullible, I definitely feel less hesitation when I punch at the throttle from a leisurely cruise to WOT. I recommend this mod even if it's not going to give an incredible gain in performance just for the sake of not having hot air and black goo recycled through your engine possibly leading to some type of build up and definitely negating benefits from a cold air intake. Some time during my holdiday break I am doing the coolant bypass as well. I did that one on my Tiburon just for the hell of it. I'll keep you guys posted on any possible oil misting on my engine from the filter. Thanks guys for the knowledge.

mysql101

put in a catch can and you'll quickly change your mind. The vapors need to touch things and cool down to change into liquid form. Just venting it isn't going to prove anything.

Zielritter

Just a follow up post for you guys. I finally got around to doing the throttle body coolant bypass, and it went pretty smoothly once I managed to get to the tube that ran under the tb. Anyways, I got a first hand look at the carnage the stock crankcase venting system was causing in my intake tube when I removed the accordion tube. That brown viscous goo in the ribs of the accordion is disgusting. I was able to get almost a handfull of it out. I can't imagine that crap getting sucked into my engine and having to be burned effectively. I guess this explains my now smooth idle as compared to the random convulsions my 8 had at stop lights before the breather vent. Clearly not having to deal with all the extra gunk and other contaminant smooths out the engine.

CURED RX8

First I'll offer the attachment...You can apparently get the new '06 version done at the dealer if you choose.

I have an '06 with the version fed to the lower manifold instead of the intake. I assume with what little oil vapor is vented out the overflow tube, it is easily all combusted with no residual left behind in the chamber.

My question is...The gunk people are pulling out of their intake is oil residue that clings to the walls of the intake with dust, dirt, etc. getting stuck to it, correct?

So instead of messing with messy breathers, or adding cans to clutter up the engine compartment, not knowing the vaccuum requirements, etc. etc. Why not just get the new '06 version. Mazda will apparently do it if you complain, and if you don't like them working on your car, the instructions are in the attachment here. Clean intake=HAPPY!

Or is there something with the '06 version that isn't good that I am missing!

Spin9k

Yea this looks to be the simpilest thing in the world a hose with y adapter. Great idea and far better than messing w/catch cans, esp. if your car doesn't emmit copious quantities of the oil fog stuff.

sosonic

I'm tryng to clarify what you have posted. Are you stating the following:

1. This fix (in the PDF) will increase throttle response

2. The fix is FREE from Mazda or at least Mazda will do it.

TeamRX8

iTrader: (25)

if you have dirt an dust in your intake then you have bigger problems than this ....

but I've never seen any oil or gunk in my '05 intake; bone dry and clean, not sure why it would be a problem on some engines and not on others

Charles R. Hill

iTrader: (7)

When I first got my '04 it had a little oil in the intake. Then I cleaned it out and it didn't come back. Now that I have the new "emissions" flash I have so much oil in my intake that it is drooling out of my intake duct and getting the stock air filter wet with a little oil.

dannobre

iTrader: (3)

It's interesting..they are changing the oil filler tube and the solenoids on the manifold as well. I would suspect that the oil in intake thing might be plugging up the solenoids...otherwise why replace them??

It's a bit more compex than a y tube and a piece of hose......

They are doing mine next week....and I hope it stops the oil leak on the filler tube inlet as well

Charles R. Hill

iTrader: (7)

Which solenoids? I remember one that is on the underside of the intake near the front of the engine.

olddragger

iTrader: (3)

doesnt matter what oil the gunk goes in--it is still gunk into the intake. I have seen cars with blowback(i guess that was my problems ) and I have seen cars that people have put oil in too fast and it backs up the tube and then drains into the line. IMHO a catch can with intake suction to it or the old style downdraft tube is the best solution. I have the latter and I have VERY little coming out.
Merry Christmas all!
rotor on
olddragger

olddragger

iTrader: (3)

errrr-- to correct myself--"it doesnt matter what hole(not oil) the gunk goes in"
I curse myself.
OD

CURED RX8

"No" to the throttle response issue...or better yet "I don't know for sure". I didn't make any claim like that in my post.

"Apparently Yes" Mazda will change it to the '06 version if you make the complaint in the manner it is written in the TBS.