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Air / Oil Seperator setup?

H

hughfi

Well Known Member
Hi there,

I have an RV6 with an 0-320-E3D engine. I seem to be getting a little too much oil on the belly for my liking, especially at RPM's above 2450 with 6 quarts of oil. Its clearly coming out of the accessory case breather hose as it should but its annoying to say the least. I want to therefore install an air/oil seperator, but I cannot find a place to connect the oil return line on this engine. I have seen the appropriate place on 0-360 engines, but I cannot find a spot on mine. Any ideas would be appreciated.

Also, whats the appropriate amount of oil to maintain in this engine? Maybe this is part of my problem. I always believed it was 6 quarts, but now I am not so sure.

Thx.

Hugh.
 
Air/Oil Seperator

Don't return it to the engine, just install a small catch jar and drain it when necessary. I had a seperator on the RV4 that I used to own but I took it off after I started flying a friends J3 Cub. After every flight in the Cub, a small amount of chocolate milk colored oil and water mixture would drain from the breather tube. I didn't want that oil/water mix returned to the crankcase and removed my seperator.

Jim (former RV4 driver)
 
If a person did want a oil/air seperator with a collector (rather then a return) - which one is a good one?
 
Air/Oil Seperator

ACS has one for homebuilts that sells for $ 49 or so. Check page 301 of their current catalog for some ideas.

Jim
 
I've used a number of the air-oil separators over the years including the ACS for homebuilts, the M-20, the Andair, and the Airwolf. My experience across O-360's and IO-540's are that the Andair and the Airwolf are the best, meaning they leave the least amount of oil residue on the belly. The only thing I don't like about the Andair is having to empty the overflow container, and after seeing its contents for many hours now I have decided that it is OK to put that back in the crankcase, as it looks like clean oil. I always make sure the oil runs above 180-195 via a cockpit control which operates a flipper valve inthe air duct to the cooler, and I believe that the ones who mention the nasty stuff in the overflow tubes on Cubs, etc., are the ones who aren't achieving high enough temps to get the moisture out of the oil. I have been very happy with the performance of both the Andair and the Airwolf, but I am putting an Airwolf on the 10.
 
Separate it...

I agree with Vic on the oil separator issue. I have run three separator equipped engines to TBO without any signs of corrosion or rust on teardown. With proper oil temperatures, it is a non-issue. And no, it doesn't need to be over 212 to make the water evaporate.

John Clark
RV8 N18U "Sunshine"
KSBA
 
You might want to search the forums before you do anything. There was a discussion on oil separators a few months ago and as I recall the consensus was to not use one but to have the breather drip onto the exhaust & let it burn off the drippings. Probably wrong about the details, but I do remember there were several folks who didn't think much of the separators.
 
same question as original poster...

Mounted my Anti-splat air/oil seperator and can't find anywhere to attach the oil return line. (O-320-E2D). I remember in one of Tony B.s books he suggested putting a fitting on the dipstick/oil filler tube for the return.
Thoughts...suggestions...what you did??

Thanks
 
I have been using an Anti-Splat Air Oil Sep. for around 100 hours now. Belly is clean and oil consumption about half what it was. I tried using the accessory case return port, but found that the oil return tube worked better.
IMG_2867.JPG
 
Return or not return?

I would point out that if you use a catch can, oil from the separator as well as crankcase gasses will pass thru the drain hose into the can. The can being chilled at altitude will of course turn into a nice little still and condense vapors in the gas into the nasty muck some use as evidence of how bad it is to return it. Mike Busch even has a picture of it in one of his articles.
This is an almost religious argument, but I've never seen any real evidence that returning is bad. It evidently is approved by Lycoming as there are examples from the certified world of separators. Of course none of those mfg's ask their owners to empty the can, they all return to the crankcase.
FWIW, I did have Blackstone test my oil before and after installing my separator, specifically asking about water content, acids etc., there was no difference in the samples.
I'm not trying to convince anyone one way or the other, I just think the muck in the can is a red herring and you'd see the same if you condensed the gases from your crankcase vent.
Just one opinion...
Tim
 
JimS said:
Mounted my Anti-splat air/oil seperator and can't find anywhere to attach the oil return line. (O-320-E2D). I remember in one of Tony B.s books he suggested putting a fitting on the dipstick/oil filler tube for the return.
Click to expand...

Turbocharger return port on the lower right side of the accessory case, or tap the #3 cylinder's oil drain line as Bill has done.

72yp94.jpg


tim2542 said:
I did have Blackstone test my oil before and after installing my separator, specifically asking about water content, acids etc., there was no difference in the samples.
Click to expand...

Tim, any way we could talk you into posting those oil test reports? Happy to do it for you if desired.
 
Thanks for the replies...

No plugs anywhere on the acc. case so #3 oil return line it is.
 
Oil reports

Be happy to Dan, I sent you a pm.
Also, I misspoke, I was using Aviation oil Analysis before the separator install. I switched to Blackstone since then, they have a more comprehensive report, but the reports were about the same before and after. And Blackstone was requested to look for any issues with water, acid etc.
Tim
 
AeroSplat air/oil seperator

I installed an AeroSplat air/oil seperator on my RV-6 (O-320) last month, and I love it! I fly 1.6 to 2.5 hours per week (~100 hours/year) and was really tired of wiping the belly every week. After the AeroSplat installation I had zero oil on the belly! I should have expected this, since I used the whole system which includes the drain hose being inserted into the exhaust, but I had become so accustomed to wiping off the belly that it was a huge relief to see a completely clean belly after each flight.

I do oil analysis at each oil change, but will not be changing the oil for another 20 hours, so it'll be a while before I have a baseline for before and after the installation. After research and contemplation, I don't expect to see a difference in the analysis, but I'll post here if I do see a change.

The guy at AeroSplat was great at answering my questions both before AND after the purchase. It's a really straightforward installation, I put the seperators return into the right side, aft cylinder, oil return line with a "T" (as pictured in post #10). I don't know if I'll see a reduction in oil consumption, but I'm already extremely happy with the clean belly.

Feel free to contact me if you have questions about the installation or my reasoning process for the oil return issue.

Mike
 
tim2542 said:
Be happy to Dan, I sent you a pm.
Click to expand...

Thanks Tim. I'll look for the report via email.

I've been contacted by another owner with a before-and-after oil analysis record and now have it in hand. I'd love to collect a few more, both to look for trends and to validate them. I'll publish everything for which I have permission; easy to strip all ID information when desired.

So who else has an oil analysis record, before and after separator installation?
 
I have done Blackstone oil analysis since hour 0 on my Barrett IO-540. Recently installed the Anti-splat separator, and will be sending Blackstone the first post-install oil sample tomorrow. I will send you the results in a few days. I have seen no change in oil consumption, but I lose only 2 qts. in 25 hours.

Jim Berry
RV-10
 
Air/oil seperator

I have a lycoming io360 with a 3/4" vent fitting on the engine. I also have an acs oil separator. It has a 5/8" connection. Is it acceptable to use a 3/4" to 5/8" reducing fitting with 5/8" hose.will this create to much back pressure?
Thank you. Bob
 
Probably not, but why assume? It is very simple to tap the system with a manometer and measure any change.
 
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