Airwolf Minisep Air/Oil Separator

Guys, I thought I was done ... but I must have had a premonition because I already have a baby bottle with the top modified "just in case". Actually I prepared it just in case oil still blew out of the MiniSep outlet. I don't think I can get to it for a while but I will "git er done".
Darrel

On an O320 where do you hook up the oil return line from the separator?

Mike

Is there a reason you can't run the breather line from the crankcase directly into a baby bottle, and not use a separator at all?

Tim

Tim, Tim,

We're trying to stimulate the economy and put Americans to work here! If we all resorted to make-do solutions like baby bottles the economy may tank and I wouldn't want to be the one everybody is pointing at.

Besides, by recycling the sludge back into your engine you are saving the environment. Also, by not paying exorbitant disposal fees, you are saving yourself enough money (over a NUMBER of years) to pay for the oil separator.

Of course also, the oil separator has an STC and that baby bottle will need an unobtainable 337.

John Scott

What if we were to mount an approved baby car seat under the cowl and had a real baby hold onto the bottle, would we still need a 337

Glenn

Mike -- the return goes into a hole (where an 1/8 inch pipe plug now is) on the mid right side of the accessory case.
You could go with the baby without a 337 BUT in the long run this would be more expensive. My experience with grandbabies is that they eventually emit some strong odors that would require a $200 CO detector to avoid knocking out the pilot.
Darrel

Tim said:

Is there a reason you can't run the breather line from the crankcase directly into a baby bottle, and not use a separator at all?

Tim

Click to expand...

thats the normal way... just make sure the bottle top has more holes than the breather size

And if you look at my previous post where water was condensing in the bottle,,, I believe I have an answer....I dont think it is coming from the separator,, it has been somewhat cool to cold when I am flying... I believe the hot air coming out of the drain tube is causing water to condense in the cold baby bottle... I dont believe that much moisture is coming out of the tube itself..

So far I have put several hours on the setup and NO oil even coming out of the breather tube,,, you can stick your finger in it and there is not even any residue... very happy.

Time for a bit of redesign. The Minisep worked fine while ambient temps were in the 70s and 80s F but now that the ambients are running in the 40s, I'm getting water vapor condensing in the outlet line and since the Minisep is only 80% or so efficient, there still is just enough oil in the condensation to have the stuff look like Mocha. Only a few drops per flight hour but it still makes a mess even if the mess is smaller than it used to be without the separator. Also, the Scat tubing on the outlet will not seal tightly. It allows some condensate to leak around the edge. So I replaced the Scat tubing with the same silicone hose that I bought from Aircraft Spruce for the line leading to the separator (part # 05-00671).
Then I got a plastic water trap from an air compressor and mounted it next to the gascolator to create a "baby bottle" sump that I can drain easily (there is a red plug in the outlet at present but I have a quick drain ordered like the one on the gascolator). So what is the point of the separator you might ask? Good question. Actually, I expect very little condensate to accumulate in the bottle compared to the volume if the separator were not in the system and in the summer possibly nearly none. Some of my best friends claim I just don't have enough to do in retirement -- that could be the bottom line here.
Darrel

Update on the separator,,, All is fine for a long time,,, until.....

Several things happeded at once and it took me a while to figure it out... First, I started to develop a leak from the acessory case gasket,,,, then my mags needed points,, put new points in and put mags back on.. but at this time I decided to pipe the drain out of the oil separator into the acessory case....

I tightened up the acessory case bolts snugly.... Go fly,,, come back and walk around the plane opening up cowling doors.... OIL ALL OVER THE LEFT SIDE OF THE PLANE,,, now I am not talking a little,,, BUT A LOT,,

Go into emergency thinking mode.. pull all cowling off...

The hose going out of the engine to the separator slowly kinked itself because of the tight bend,,, thus causing no breathing,,, which caused the engine to breathe backwards... up through the oil drain,, and back through the separator and out the breather tube onto the belly and side of the plane....

So I cut the kink out and replaced it with a (not sure what the correct name is) conduit that electricians use (the grey stuff).... anyway you can buy a 90degree bend and I heated it up with a propane torch to bend it to about a 180 or a little less...plugged it in both ends of the hose and wala,,, no more kinks at all,, and cant kink... I was going to use metal conduit, but dont think I could get it to bend that short and tight without kinking..

Thus, now the engine breathes and the acessory case is not leaking now...
So,, No kinking allowed... Fortunately I had just hooked the oil drain hose up to the separator and it could breathe backwards,,, or there was a good possiblility of blowing out the prop gasket...

Wow Steve, glad you caught it with no more damage than an oil spill. The hose that kinked -- was it one of the bright blue silicone ones like I have on my system? I will take another look at mine too.
By the way, I really like the "breather sump" I sdded -- see pictures in an earlier post - just make sure the top of the "sump" is wide open to the atmosphere. In an hour's flight at 30F air temp and with oil temp maxing out at 172F, I collected about an ounce of water that had a thin skim of scummy oil on it. I just drain this out at the end of a flight using the same plastic container I use for the gas drains. Now I get nothing on the belly. Before this "sump" was added (lots of people use a baby bottle) water vapor with a small amount of oil was condensing on the belly in cold weather.

Darrel

Yes Darrel,, it is the same hose...Watch out for kinks,,,, Before I put the oil drain hose back in the accessory case,, I dumped it in a baby bottle.... But being very cold out and the hot air going in the baby bottle caused condensation... I could get 1/3 water in the bottle on a cold day... then that night it would freeze and my drain hose was then frozen in a chunk of ice....

Steve, thanks for the info, I'll watch out. I did buy "just in case" a couple of tightly bent 90 degree 3/4 dia alum tube sections from an outfit in Detroit. As I first started to install the separator, I planned to ask Bob Eckstein to weld these together to form a nice tight 180 degree turn. So far I haven't felt I needed to do that since the blue hose made the turn and, I think, keeps the vapor warmer on its way to the separator. But, with your experience in mind, I will stare at the installation one more time and possibly revert to that original design.
Darrel

Another update...


TOOK IT OFF!!!

I had it mounted right next to the #4 cylinder to get as much heat as possible... But it has to be 212 degrees and it was not happenin....

Oil and moisture condensed in the steel wool and although it probably did not freeze,, it gelled up and looked like snot. It would not let the filter breathe and it backflowed from the accessory case and out the breather tube and blew oil out all over my plane again... All this happened on a cross country where the rpm's were 2450... Fortunately it happened not too far from a planned fuel stop... If it had happened earlier,, I might not have caught it till the oil pressure went to zip...

Outside temps were in the 20's

I talked to Johnny at Airwolf and he said to rob some heat off the top of the cylinders with a small scat hose and point it at the separator.... I thought that would be like some Government program that didnt work, it so I didnt do that...

Then he suggested just to unhook it in the winter and put it back on in the summer,,, when the temps are higher... Not really a pain in the butt,, just a hastle..

So,, for now and probably forever,, it is off....The back of the cowl is open so much,, it is hard to heat it up...

SteveE, sorry it didn't work for you. The last I flew, the ambient temp was 25F and the oil was at 172F. I got about an ounce or two of water in the "baby bottle" in about an hour with just a scum of oil on the water. So all seems well -- no milky signs of oil in the sump. I have my oil separator clear on the far right side behind the #3 cylinder with a branch of the Leading Edge exhaust system just under the separator. So mine seems to be working as advertised at least it does down to 8F. It looks like the exhaust being close by is an important factor.
Darrel

Could be true about the exhaust Darrel,,, I have a Sutton exhaust in the front.

Two questions:

1. can this be used on a C90?

2. is there an STC required or what is the paperwork?

thanks in advance.

A lot (most or all?) of vacuum systems that use a wet vacuum pump incorporate an air/oil separator.
They're usually plumbed back into the engine, at the case or a valve cover.
FWIW I have one of those air/oil separators, if anyone wants to buy it for use as a crankcase breather.
Dunno if I'd want to plumb the stuff that blows out of the crankcase breather back into the engine though--
think I'd plumb it into a bottle & empty it out every few flights.