Oil seperator questions

Charles in SC · #1 10-18-2018, 08:32 AM

Sometime back I purchased and installed an RMJ AERO oil seperator. Two questions for those that have them. The crankcase vent is a 5/8 and the seperator intake is a 3/4. What is a good way to make the transition without welding a new intake spout on the seperator? I cannot find a fitting for the engine side that looks like it will fit. Also what is a good way to connect the oil return to the engine? I have a return line from Anti Splat with a fitting welded in it but after looking at it awhile I am not sure I like that idea. The seperator came with a little strap with a tube in it to put in the oil dipstick but I am not sure I can get enough fall for it to drain properly. The seperator is mounted as high as I can go on the firewall. I have an IO 360. Thanks for any input!

DanH · #2 10-18-2018, 09:16 AM

https://www.homedepot.com/p/SharkBit...7LFA/202798048

The accessory case has a turbocharger oil return port down low on the right side, usually plugged with a 3/8 NPT allen pipe plug, #13 below

Charles in SC · #3 10-18-2018, 10:09 AM

Thanks Dan I will look for that fitting on tha accesory case. Also I know about that kind of reducer like the Home Depot one you linked but if I use something like that there is not going to be much hose left for flex. Also I try to stay away from hardware store parts.

TS Flightlines · #4 10-18-2018, 10:53 AM

On Ed's RV8, we downsized the separator stubs fittings to 5/8 in the crimper, and he then clamped his hose onto the separator.

Tom

It would be nice if they had AN males on them--

DanH · #5 10-18-2018, 11:02 AM

Quote:

Originally Posted by Charles in SC

Thanks Dan I will look for that fitting on tha accesory case. Also I know about that kind of reducer like the Home Depot one you linked but if I use something like that there is not going to be much hose left for flex. Also I try to stay away from hardware store parts.

It's a breather hose. That brass reducer will not be a problem...but for the low, low discount aviation-grade price of $50 (that's right folks, believe it or not, only 5% of an AMU!!), I will cheerfully machine one to your drawing, from 6061-T6

airguy · #6 10-18-2018, 02:11 PM

Quote:

Originally Posted by DanH

It's a breather hose. That brass reducer will not be a problem...but for the low, low discount aviation-grade price of $50 (that's right folks, believe it or not, only 5% of an AMU!!), I will cheerfully machine one to your drawing, from 6061-T6

Oooohhhh!! That's military-grade, right?

Charles in SC · #7 10-18-2018, 06:28 PM

Quote:

Originally Posted by DanH

It's a breather hose. That brass reducer will not be a problem...but for the low, low discount aviation-grade price of $50 (that's right folks, believe it or not, only 5% of an AMU!!), I will cheerfully machine one to your drawing, from 6061-T6

Thanks for the offer Dan, I will make my own if I decide to go that route.

bob woods · #8 02-25-2019, 10:29 PM

Is there a crankcase pressure problem by reducing the 3/4? fitting on the accessory case down to 5/8? at the air / oil seperator ?
Thank you
Bob

Carl Froehlich · #9 02-26-2019, 08:27 AM

Consider collecting the oil draining out of the separator instead of returning it back to the engine. A small can like an old Brasso can is more than adequate for a year of flying.

This set up has worked well on my projects and others.

Carl

snopercod · #10 02-26-2019, 10:59 AM

What Carl said. Originally I had my separator draining back to the accessory case via the location Dan mentioned. My oil analyses kept coming back "high silicon". Since my crankcase vent hoses are all silicone rubber, I thought that might be the problem. Apparently it was because when I switched to a small 1/2 pint metal catch bottle, I no longer had high silicon in the oil.