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NSI normal asperated oil blowoff

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smokey_bear_40220(at)yaho
Guest

Posted: Mon Jul 09, 2007 3:12 pm Post subject: NSI normal asperated oil blowoff

Hi again Clem,



Retirement plans?  I was suppose to plan this???  Ha

ha



Anyway I have a question for you and any other Soob

guys who may have their oil tank on the firewall.



Another Soob KF driver has this firewall oil tank with

his NSI and it blows a good bit of oil out his tank

vent line.  I don't have this.  Mine has the auto oil

pan instead, so I am not sure if this problem has been

resolved previously or not.



So have any of you had a lot of oil blow out of your

tank and how did you fix it?



Do your valve covers vent to the oil tank, thus

pressurizing it a bit?



Does this tank have a baffel under the vent port?



And how full is "full" for this tank?  In other words,

how close is the oil level to this vent port?



Thanks,



Kurt Schrader

S-5/NSI turbo

Florida and panama

 

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Guest

Posted: Mon Jul 09, 2007 4:13 pm Post subject: NSI normal asperated oil blowoff

--

Clem Nichols

Joined: 10 Jan 2006
Posts: 88
Location: Munfordville, Ky

Posted: Mon Jul 09, 2007 4:31 pm Post subject: NSI normal asperated oil blowoff

Kurt:



I'll try to answer your questions as best as I can.  There are no vents on 

the valve covers, so I assume they must vent to the firewall tank. 

Regarding a baffel under the vent port, I really don't know.  The oil level 

when full is 2 to 3 inches below the top of the tank in the tail down 

position.  My experience is that as long as the oil is kept at the proper 

level there's not much blow-off out the vent line.  If you add a little too 

much oil, however, (which for some unknown reason I seemed to do when I 

first got the plane) there's a considerable amount of blow-off.  Perhaps you 

remember that on my plane the vent line goes to a half-quart beer can with a 

plastic bottle and foam rubber in it.  (How's that for high tech?)  There 

were a couple of times early on when it filled to the point that I was 

getting oil mist back on the windscreen.  Needless to say, a tense moment or 

two.  When I checked the can, it was pretty full of oil, not 16 ounces, mind 

you because of the foam rubber in the bottle, but enough to get some 

misting, nevertheless.  Thinking back about it while writing this message, 

it seems that NSI said to keep the oil level within so many inches of the 

bottom of the cap, and that was what I was doing.  When I changed the oil 

and filter and added the proper amount of oil my level was a little lower 

than their recommendation.  I made a mark on the dip-stick, and have never 

filled the tank above that level.  I've not checked my beer can reservoir 

lately, but have several hours on the last oil change, and the level in the 

tank is within no more than a quarter of an inch from my mark which I assume 

is due to burning rather than blow-off.  At least I've not had any oil mist 

on the windscreen.  I have to do an annual condition inspection this month, 

and will check the level in the can at that time.



Clem

---

Clem Nichols

Joined: 10 Jan 2006
Posts: 88
Location: Munfordville, Ky

Posted: Mon Jul 09, 2007 4:39 pm Post subject: NSI normal asperated oil blowoff

Peter:



That's my conclusion, also.  Too much oil in the tank, and it will blow out.



Clem Nichols

---

smokey_bear_40220(at)yaho
Guest

Posted: Tue Jul 10, 2007 10:01 pm Post subject: NSI normal asperated oil blowoff

Thanks for the help so far on this so far.



Peter G, I think his plane and engine are same as

yours, minus your many mods.  Unfortunately he is not

the builder, so his plane is more of a mystery.



I am still worried about this Soob driver's oil

problem.  Here is what he said after reading all of

your replies.



"From the full mark on the dipstick to the 90 degree

angle of the outlet line is 5".  I am sure I'm not

over filling because when we ran at 4800 RPM it

dropped 2qts out and the oil pressure went down to 20

lbs of pressure.  We landed quick and found we had to

put in the 2qts to bring the oil back up to operating

range."



2 qts is a lot and the low oil pressure tells me there

is more to this.  But he says it is blowing only out

this vent line and because it was lengthened, the

belly stays clean.  I am wondering if he is not seeing

it blow out the exhaust or something at higher power

and that is the reason for the excess loss?



Also why are the top 2 qts so critical?  Shouldn't it

hold pressure with the last 2 qts?  I would think as

long as the engine, oil lines full, and at least a

little is in the tank he should hold pressure.  There

has to be more to this story.



Is there a way to reverse some lines coming from the

oil tank to miss the bottom 2 qts?  My impression is

that there are only 3 lines - tank to engine pump,

return to tank, and vent.  But he says there is

another line from the bottom of the tank going down

and capped off.  I thought this was a convenient drain

line to reduce the mess when changing, but is it

supposed to be the line to the oil pump instead and he

is pulling oil from another line swapped by mistake?



How are your oil hoses set up?



Still doesn't account for the excess loss of 2 qts.



Any ideas?



Kurt Schrader

S-5/NSI turbo

Florida and panama

       

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MHastedt

Joined: 27 Aug 2006
Posts: 14
Location: College Station, TX

Posted: Wed Jul 11, 2007 10:00 am Post subject: NSI normal asperated oil blowoff

Hi everyone,



I was discussing this with my friend and he made an interesting point:  it's possible that the lengthened vent line may be in a low-pressure location and is literally suctioning the oil out of the resevoir.  I had this very issue early on with the vent on my Hirth reduction drive.  It was on the front of the redrive and in a low-pressure zone behind the propeller.  It literally vacuumed almost all the gear oil out of the unit in a short amount of time!  I've since relocated the vent to the top fill port (pointing backwards) to solve that issue.



My $.02 for what it's worth...



Margaret H.

Classic IV with "NSI" EA-81

College Station, TX

Michael Logan

Joined: 10 Jan 2006
Posts: 82

Posted: Wed Jul 11, 2007 1:35 pm Post subject: NSI normal asperated oil blowoff

Kurt,



I had the same engine in my series 5 and had the same problem losing oil.  I

ended up doing three things; first I put a screen in the fitting at the top

of the tank where the blow by comes out.  Second I put a catch bottle in

that blow by line to catch any residual oil droplets and not let it go out

the line.  The catch bottle worked like a separator similar to the M20 that

some put on certificated spam cans.  The third and most important thing I

did was to put a downward facing tube onto the return line that goes into

the tank at the front top on the pilots side.  I put holes in the tube to

help keep the pressure from foaming the oil.  All of these helped me keep a

little more oil in the engine.  



I believe I had a bad engine to begin with and it had a lot of blow by

pressure because of poor quality control at NSI at the time.  Without the

above modifications, I could not keep more than two quarts in the engine and

it would run very hot and it never had good oil pressure.  With the

modifications, I was able to keep about another quart and a half and it

helped with the cooling even though the oil pressure never came up.  Not

enough to be truly safe but enough to run in the winter time.  I have since

gone to a RAM engine and hope to have it flying again soon.



Mike Logan

Series 5



--

_________________
Mike Logan
Fredericksburg, VA

smokey_bear_40220(at)yaho
Guest

Posted: Wed Jul 11, 2007 5:45 pm Post subject: NSI normal asperated oil blowoff

Thanks Michael,



I was leaning in about the same direction with him

before I asked you all on the list.  Your experience

is the first I heard to match his though.



I thought he could put a section of scrubbie in the

vent line after the connection, but before the 90 down

turn so it would stay there.  Blow thru it to make

sure air still goes thru.  There is no room to make

this line go verticle up before going down, or he

could get some drain-back.



Second, I though like you and Peter, to add some kind

of air/oil seperator to the line.



Hadn't thought of your third mod though.  Sure enough

that return line would be blowing oil all over the

tank's insides and not down only.  Makes it a lot

easier for oil to go right out the vent without it.



I agree that you and he must be getting a lot of

blowby due to bad rig arrangement or something.  Valve

guides?  In any case, nothing so easily fixed for him.

 He is not a mechanic.  Your mods might do it alone.



Another option I thought of was an expanded tank

volume like a lower tank even with the bottom of the

main, but only 1/2 as high that held an additional 2

qts.  But that low oil pressure worries me more than

the blowout.  As you said, quality control.



Let us know how the RAM conversion works out.  How

exensive a change are you making?  The whole

conversion, or only parts?  Been thinking about some

mods myself.  My engine runs pretty well, but it could

be better and I have a few things in mind.  RAM might

play a part in it for me too.



Kurt Schrader

S-5/NSI turbo

Florida and Panama

 

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smokey_bear_40220(at)yaho
Guest

Posted: Wed Jul 11, 2007 6:14 pm Post subject: NSI normal asperated oil blowoff

Hi Margaret,



Good thought!



It is likely a pressure differential, and the tank

line configuration that allows it to suck or blow the

oil out.



I think the main problem is too high a crankcase

pressure due to excessive blowby, rather than low

pressure at the vent.  Almost certainly bad pressure

at one end or the other.  In any case, this is

followed by an arrangement that doesn't trap the oil

while letting the air out.  If he can fix up a good

trap, let it suck or blow as necessary, but the

venting will not take out his oil.



My friends told me that Soobs break in at about 300

hours.  Before that expect hotter runs and more oil

loss.  After that it suddenly ups the power and runs

right.  My engine isn't there yet for me to say.



But with this much blowby his engine needs some really

good oil trap mechinism and it may take longer to seat

in too.  Don't know.



The more expensive, but solid answer is a rebuild to

make things right to begin with.  But if he can come

up with a good oil trap, he can fly it until it all

fits properly.



He is now in contact with Peter G for direct

assistance from someone who has the same engine, not

thru me with a different system.  That should help

more than my guesswork.



Kurt Schrader

S-5/NSI turbo



--- Margaret Hastedt <hastedt(at)iodp.tamu.edu> wrote:



 	  Quote: 	
		   Hi everyone,

 

 I was discussing this with my friend and he made an

 interesting point:  it's possible that the

 lengthened vent line may be in a low-pressure

 location and is literally suctioning the oil out of

 the resevoir......


	


 	  Quote: 	
		   Margaret H.

 Classic IV with "NSI" EA-81

 College Station, TX


	




       

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Michael Logan

Joined: 10 Jan 2006
Posts: 82

Posted: Thu Jul 12, 2007 2:34 pm Post subject: NSI normal asperated oil blowoff

Kurt,



I did the whole enchilada, a completely new engine with dual intake heads

and the injection/ignition system built by Tracy Crook for RAM.  The work is

going very slow, I have a four year old daughter and my wife's Grumman

Traveler to keep me busy and flying.



Mike 



--

_________________
Mike Logan
Fredericksburg, VA

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