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Oil Breather-Separator


Ghost

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I have a Continental 0-200 on my VariEZe project. I recently purchased an Oil Breather Separator from Spruce.

 

I am researching the different options for installing the oil return line. I saw one install the drills a hole in one of the valve covers, and you tap in a fitting. Another technique drills a hole in the oil fill tube.

 

I am interested in what techniques used by this forum have yielded the best results.

 

Any feedback is greatly appreciated.

 

Ghost

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CP 56 page 5 shows the technique used by Mike Melville. Better yet is a better description by Dick Kreidel in CSA 58 page 13---this is what I used on my Longez. Basically AV-7 airpump valve screwed onto a pipe nipple that was welded at a certain angle into the exhaust pipe. Breather hose went straight to the valve which prevented the exhaust from pressurizing the crankcase. Totally cleaned up the belly.

 

Better to blow it out the back into the exhaust than to try to return it to the crankcase.

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Drew,

 

Thank you for the feedback. I am installing the (according to Spruce) Rutan designed experimental Oil Breather Separator.

 

Homebuilders Oil Breather/Separator (PN 10570)

These 4 inch diameter reservoirs have beaded outlets for 5/8" I.D. hoses and a mounting flange for easy firewall attachment. These units are of a new, improved design and the reservoir body is now a spun aluminum bowl for optimum performance. The oil separators minimize oil loss and allow free breathing of the engine. They are recommended for experimental aircraft use only and are not STCd for any certificated aircraft.

 

I am not too concerned with the venting/outlet line, the original builder of my VariEZe very cleanly glassed in a vent tube into the cowling to the back near the prop. As mentioned before I am more interested in identifying what the best place to connect the Oil Return line.

 

Being that I currently have my oil kidney off (due to an unrelated modification) I was thinking of banging a small flat spot on the oil filler tube, drilling a hole, and screwing in a 90 or 45 degree fitting. The flat spot will facilitate the opportunity for me to screw a nut on the back of the fitting creating a tight leak (with a gasket or O-Ring) resistant seal. The fact that I have the oil kidney off, will allow me to recover the nut that I inevitably will drop several times during the process.

 

I saw a similar (simple) method with a thick ring-clamp with a hole in it, holding the fitting in place, very similar to the method used to hold an exhaust gas temperature probe in place.

 

Any feedback before I drill would be greatly appreciated.

 

Ghost

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I would not return oil back to the engine. You could as an experiment, run the return line to some sort of catch container. Take a look at it after it fills up, and then determine if you really want to return it to the engine.

 

I had the same oil air sep on my Longez. I sold it and used the mechanism as described in the articles that I pointed out.

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I would not return oil back to the engine. You could as an experiment, run the return line to some sort of catch container. Take a look at it after it fills up, and then determine if you really want to return it to the engine.

 

I had the same oil air sep on my Longez. I sold it and used the mechanism as described in the articles that I pointed out.

Better to blow it back in the engine. if you have a condition that is blowing it out of the engine and back into the engine you get to keep all the oil until the flight ends. if it goes overboard you could run out of oil before you get to the next airport. this is not good. blowing it overboard is also not very Green

Evolultion Eze RG -a two place side by side-200 Knots on 200 HP. A&P / pilot for over 30 years

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I don't like that it's not a green solution, but I too choose to let the blow-by go. I don't want the oil, containing nasty by-products of combustion, to be returned to the engine. I think it is best to let it go or catch it to be disposed of properly. I wish I could find the source, but I have read that oil from the breather tube is not what you want lubricating your engine. Isn't it acidic?

Dave Adams

Long EZ N83DT

Race 83

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I installed the same oil/air separator from spruce. It took me a while and few iterations to find a working config ...

 

1) to make the separator piping simple, i plugged the normal engine breather outlet, and located the new breather on the mag cover plate (the one supplied by LSE to close the mag hole when installing an EI)

The oil return line was connected to 1/8 gallon tank

==> due to gears, this place is very oily, the oil return line was filling the 1/8 gallon tank in 1/2h flight, after this the oil separator fills up and is no more efficient.

 

2) i changed for an elongated breather tube and added the oil return line on the same mag cover

==> the oil was not returned to the tank, the separator fills up with oil and after 1/4h-1/2h the rejected air is very oily

 

3) i put back the original engine breather and connected it to the separator

It works far better, separator do not fill up, oil rejected is lower.

==> the original breather location is a good one !!!

 

4) in progress ... i change the oil return connection to engine, i have rebuilt a new mag plate cover without breather but just oil return with reduced ID

 

Remark : on the bottom of the accessories case of O-200, there is a threaded hole for oil return ... i may use this one in a further test

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The purpose of getting an oil breather/separator as I understand it is two fold.

 

1) The obvious is to efficiently vent the crank case. Efficiently, because this process does displace oil, and can be very messy, the properly installed breather vents with minimal mess. An added benefit are reduced oil leaks; I have read a few articles on the web in which a properly installed oil breather can reduce oil leaks by significantly reducing the pressure in the case.

 

2) The second purpose is to recover the oil that is lost during the venting process.

 

I will agree that there are combustion by-produces (Drew) in the oil, and obviously some moisture that no one is interested in introducing into their respective engines, but the separator/breather process doesn’t add any of these, they are already circulating in the engine.

 

A well tuned engine will burn a small amount of oil per flight hour. We can choose to let it blow-out (LongEZDave) and replace it as needed, or we can attempt to recover it, and add oil less frequently.

 

If your not using an oil breather / separator, how do you know how much oil your engine is really burning ? A percentage is undoubtedly being kicked out during the venting process.

 

Coyote, thanks for the description of your install, and the great photos; just an observation, is it possible that your install may be experiencing a pressure lock ? If the engine vent line and the oil return line are connected to the same place, wouldn’t the pressure venting from the crank case keep the recovered / separated oil from returning to the engine?

 

The feedback to my inquiry has been exceptional, thank you all, and I look forward to posting photos of my installation once completed.

 

Ghost

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So mine goes thru the separator and then is routed out with a pipe that blows onto the exhaust. Did not care for holes in the exhaust ...

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I live in my own little world! but its OK, they know me here!

Chris Van Hoof, Johannesburg, South Africa operate from FASY (Baragwanath)

Cozy Mk IV, ZU-CZZ, IO-360 (200hp) 70x80 prop

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Coyote, thanks for the description of your install, and the great photos; just an observation, is it possible that your install may be experiencing a pressure lock ? If the engine vent line and the oil return line are connected to the same place, wouldn’t the pressure venting from the crank case keep the recovered / separated oil from returning to the engine?

 

Exactly, i forgot to tell that the picture is the config "2" that do not work...

Basically, all lines are connected to the crankcase, so the pressure should be roughly the same wherever you connect it ... but in reality the pressure pumps up at each ignition due to leaks, so it is interesting to have the oil return line at a different location versus breather line. Also it is preferred to have it the lowest, thus gravity helps oil to return.

 

 

From my experience, here is some basic rules to have in mind to lower oil consumption by breather port:

 

- Reduce air flow : a good condition of cylinders/piston/rings will reduce air leaks that need to be rejected threw the breather

 

- Lower oil content in air : the lower oil content is at separator inlet, the lower the oil content will be at separator outlet ...

the breather port location is important; also here gravity helps, in most of case original location is on top of crankcase. In case of continental with no starter, it looks like top of starter cover plate works also quite good.

 

- internal design of separator : it is a combination of

* centrifugal load : inlet enters tangential to the wall to have oil coalescing on separator walls

* air velocity change : when air enters separator, it slows down, then reaccelerate to go out. Oil having a higher density than air, they separate. the higher internal volume, the better the separator will work.

* gravity : outlet is normaltime on top and shifted from the wall

 

- the oil separated need to escape the separator fast and easily

 

- in case of continental

* the aerobatic type breather assy helps reduce oil in air

* the vacuum pump gear needs to be removed from camshaft to avoid agitating oil close to breather; adding an oil return line between vacuum pump and sump to avoid the cavity to remain full of oil close to breather location.

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LOL, That is NOT an oil separator. Never really figured out just what they had in mind there but it sort of goes in there and sits against a nice cold firewall and does something then runs out the other hose.

 

We have tested our Oil Miser separator on a few planes with great success. Like the Velocity article says, those short warmups and short flights are not good for your engine so if that is all you do then blow it all overboard. But if your engine runs for an hour or more and you mount our separator properly it is magical, crankcase gasses and water vapors go overboard, oil goes back to your pan.

Ask Nick Ugolini and Vance Atkinson what they think of our product, they're both straight shooters, Nick won't give our prototype back!

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Miser.pdf

CG Products

www.CozyGirrrl.com

Cozy Mk-IV RG 13B Turbo

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