What's that small port that has the 1" hose attached to it on either stock or Z intake tube?

 

oil return/ catch. not sure if thats the right name, though. i do know however that is where you would hook in your oil catch can, if you have one.

Daniel

5ATC / DP / Willow / Premium / Aero / Clear Bra / 5% Tint - 30% Windshield / Ground Kit / Clear Corners / Shock Sensor / L.E.D. Hood Lights / Z - Tube / OEM Remote Window Up / VDC Memory

 

Oil return? Why would there ever be any oil in the intake tube?

 

not sure, just what i heard. and from what ive seen. hopefully someone can shead somemore light on his for us.

Daniel

5ATC / DP / Willow / Premium / Aero / Clear Bra / 5% Tint - 30% Windshield / Ground Kit / Clear Corners / Shock Sensor / L.E.D. Hood Lights / Z - Tube / OEM Remote Window Up / VDC Memory

 

I think you are referring to the crankcase/valve cover air input part of the PCV system.......metered air after MAF circulates then outputs via PCV valve to the plenum where the oil vapors are burned in combustion chambers.......at cruise air flow to engine and WOT if the pressure builds high enough [ring blowby] the flow will reverse with vapors [oil] flowing up the hose and into the TB.

See section EC page 637 of your FSM. "Positive Crankcase Ventilation"

 

Dennis:

If I were to install an oil catch can, would I connect the hose that attaches to the duct to the "in" on the catch can, and connect the "out" back to the duct?

This is the hose that goes to the CAN, right?




Thanks, Ted


'03.5 Sedan 5a: BS/G, Prem, Aero/Body, Sport, Nav
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yes you could. and should, but be damn sure you don't have a vacuum leak on top of the can.

it is normal at redline operation to have a fair amount of oil sheen on your intake tube, even new. i can stick my finger down the tube and feel oil every time. Not enough to see but enough to feel.

Better Life thru Chemistry
Black on Black 03.5 Sedan 6MT - Goodyear F1 GS-D3's 225/55/17, Custom Intake Tube, '03 "Z" Suspension, Magnaflow resonator, 6 Wire 4 Guage Grounding Kit

 

The normal PCV vapor RETURN enters inside the plenum after the throttle body - during cruise and steady speed.
At WOT there is no vacuum to suck the air thru in the normal mode so ring blow by and just churning in the crankcase sends vapor in reverse out the inlet.

Race cars use a vacuum pump to lower the crankcase pressure.

 

Dennis:

OK - I am not trying to be dense here, but are you saying that the connection above on the air duct is not our RETURN (oil can connection)?

Are you saying that we cannot attach an oil catch can because the vapor RETURN is inside the plenum(?), after the throttle body?

Just trying to get it straight.. thanks, ted



'03.5 Sedan 5a: BS/G, Prem, Aero/Body, Sport, Nav
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You can install it anywhere...........but you must decide which oil vapor you are trying to catch and condense into liquid oil [in the cannister].
Study the PCV flow and its operation under the three different conditions: Idle, cruise, and WOT.

What are you trying to fix? Dirty oily plenum interior from cruise flow or reverse flow from WOT [when PCV shuts down].

Not meaning to be cryptic but it depends on your articulating what non existent [not detremential to engine operation]problem you are trying to solve. What percentage of time are you running WOT compared to cruise idle.........A few 15 second bursts per week/day or an hour long race............Supercharging where you have positive pressure in plenum/after MAF is a special case as the PCV never works right without a redesign in hose and valve size.

When you increase cylinder pressure you create more blowby thus at WOT this can only escape from the inlet tube/hose as the PCV valve is shut [closed] because there is no/little plenum vacuum to pull it open at WOT.

On previous Nissan engines with EGR valves the necessary exhaust crud [for Nox reduction] and engine blowby vapor mixed after the throttle body in plenum neck creating a black slimy mess, that coated the rear [and under] plate of TB and the inside of plenum down to injectors where it was washed clean by gasoline spray.
With variable cam based EGR only the oil vapor from cruise should be in plenum/TB [plus what ever dirt you let in with non factory air filters].

With Synthetic oils the vaporization points are higher [all the molecules are the same size] no light, medium, heavy mixture as in conventional oils so much less evaporation of light component in base oil, so the oil vapor is significantly less to pass thru PCV system.

Rather than a catch can I would just use synthetic oils Mobil 1 or better . In the past some systems used a fine round brush inserted in the inlet hose to act as a condensing point to solve the reverse flow............you pulled the hose and used solvents to wash the brush clean or bought a new hose with a new brush inside.................all depends on how much blowby you have.........New engines don't have much unless the rings are not set or are worn quickly from bad air filters.

Oil type/quality is the usual cause of any abnormal oil in the air hoses leading to [in front of] TB.

Hope this helps.

 

I thought that hose comes from the rocker cover. Isn't it just a breather?

Nothing Turns You On More Than The "hotGspot"

 

thanks Dennis... I actually have been using Mobil1 since 500 miles.

I do drag race, occassionally [img]/w3timages/icons/tongue.gif[/img]... and i am a little heavy on the accelerations off the line...but nowhere near WOT more than 5% of the total drive time.

I have a slight film on my plenum interior....but no crud anywhere else. So I am experiencing mostly "cruise" vapor.

So your recommendation is: no catch can. Seems to match up with Gsedan35's statement that his oil can has yet to catch anything after 10k of hard driving.

thanks, Ted


'03.5 Sedan 5a: BS/G, Prem, Aero/Body, Sport, Nav
Click for MODS - www.teamtransport.org

 

can I just stuck a breather filter to the hose? I try to use straight aluminum tube btw.

Buche

Nothing Turns You On More Than The "hotGspot"

 

"I thought that hose comes from the rocker cover. Isn't it just a breather"

Modern cars less than 25 years old are not allowed to vent the crankcase vapors to the air, they use PCV systems to burn the oil/blowby by vapors by passing them into plenum.

The hose accepts metered air after the MAF and supplies fresh air INTO to the valve covers then down to crankcase where it mixes with oil vapors and is collected and back up to valve covers then thru PCV valve back into plenum.............a closed system so the MAF can account for ALL air that goes into the engine...............valve cover breathers [tiny air round filters] are used on old carb cars that don't have to meter air.