Oil breather

[BonitaRV8]

I have an AC products oil separator which was working fine up until about 10 hours ago. I now get oil on the belly after each flight. I removed it from the plane thinking it had gotten fouled but every thing was pretty clean. I ran some acetone through it to clean it out but it was pretty clean already. The return line back to the engine was dry with very little oil residue so, I think the oil is just blowing past it and out the exit tube and not back into the engine. I removed the dip stick cap and blew air through the return tube and it was clear. I have the exit tube mounted up inside the cowl about 4-6 inches above the cowl. I guess my question is where do people have their oil breather exit tube mounted and does anyone have the AC Products oil separator? I only have about 125 hours on a new Titan IO370.

 

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I have an AC products oil separator which was working fine up until about 10 hours ago. I now get oil on the belly after each flight. I removed it from the plane thinking it had gotten fouled but every thing was pretty clean. I ran some acetone through it to clean it out but it was pretty clean already. The return line back to the engine was dry with very little oil residue so, I think the oil is just blowing past it and out the exit tube and not back into the engine. I removed the dip stick cap and blew air through the return tube and it was clear. I have the exit tube mounted up inside the cowl about 4-6 inches above the cowl. I guess my question is where do people have their oil breather exit tube mounted and does anyone have the AC Products oil separator? I only have about 125 hours on a new Titan IO370.

I have an Anti-Splat oil separator on my RV-7A - no return to engine - exits into the exhaust - Belly still gets very sooty

 

[rv8ch]

I have an AC products oil separator which was working fine up until about 10 hours ago. I now get oil on the belly after each flight. I removed it from the plane thinking it had gotten fouled but every thing was pretty clean. I ran some acetone through it to clean it out but it was pretty clean already. The return line back to the engine was dry with very little oil residue so, I think the oil is just blowing past it and out the exit tube and not back into the engine. I removed the dip stick cap and blew air through the return tube and it was clear. I have the exit tube mounted up inside the cowl about 4-6 inches above the cowl. I guess my question is where do people have their oil breather exit tube mounted and does anyone have the AC Products oil separator? I only have about 125 hours on a new Titan IO370.

If it was working fine up until 10 hours ago that means something changed. Have you added more oil recently? Any changes in how you operate the engine? Any negative Gs? Any changes in the engine monitor data you send to Savvy?

 

[Ralph Inkster]

I have an AC products oil separator

I have the exit tube mounted up inside the cowl about 4-6 inches above the cowl. I guess my question is where do people have their oil breather exit tube mounted and does anyone have the AC Products oil separator?

Please describe where on the firewall you have the separator mounted.
Is the return line flowing downhill back to the case?
“4-6 inches above the cowl” do you mean the tube exit is above the bottom edge of the firewall?
Is your tube exit cut 90 deg or 45 deg & if 45 deg which direction is the exit facing, forward or to the rear?
Pictures would help!

 

[BonitaRV8]

Please describe where on the firewall you have the separator mounted.
Is the return line flowing downhill back to the case?
“4-6 inches above the cowl” do you mean the tube exit is above the bottom edge of the firewall?
Is your tube exit cut 90 deg or 45 deg & if 45 deg which direction is the exit facing, forward or to the rear?
Pictures would help!

The oil separator is mounted about as high up on the firewall as possible, about 1” below the top of the cowl and slightly to the left of center. The hose from the engine to the separator is up hill so oil should flow back to the engine. The oil return hose is also above the port on the engine so all oil in that line will flow downhill to the engine. The breather line is the one that is about 4-6” above the bottom cowl directly between the two vetterman exhaust pipes. Cut at 90 degrees. It’s the red hose in the photo. Sorry the photo is a few years old.

 

[Ralph Inkster]

OK, nothing unusual there.
One suggestion would be to reroute that red exit host so it is directly above one of your tail pipes. You would need to lengthen it so the exit was about 1/2” above the tailpipe, hopefully burning the waste oil before collecting on the belly. Makes that tail pipe messy but oh well.

Maybe perform a compression test & listen for air passing put thru the crank case & out the oil breather. This would tell you if your piston rings have an issue.
Also, has you oil top ups changed in this time frame?

 

[BonitaRV8]

Please describe where on the firewall you have the separator mounted.
Is the return line flowing downhill back to the case?
“4-6 inches above the cowl” do you mean the tube exit is above the bottom edge of the firewall?
Is your tube exit cut 90 deg or 45 deg & if 45 deg which direction is the exit facing, forward or to the rear?
Pictures would help!

The oil separator is mounted about as high up on the firewall as possible, about 1” below the top of the cowl and slightly to the left of center. The hose from the engine to the separator is up hill so oil should flow back to the engine. The oil return hose is also above the port on the engine so all oil in that line will flow downhill to the engine. The breather line is the one that is about 4-6” above the bottom cowl directly between the two vetterman exhaust pipes. Cut at 90 degrees. It’s the red hose in the photo. Sorry the photo is a few years old.

 

[Taltruda]

I have an Anti-Splat oil separator on my RV-7A - no return to engine - exits into the exhaust - Belly still gets very sooty

Lol you have the Antisplat oil separator, that separates out the oil from blow by air, only to recombine them? Why even have the separator? Just put the blow by hose out the bottom. I’ve seen people mount the hose to blast it onto the exhaust pipe to burn off the exhaust, but it seems silly to separate the oil only to say that the belly gets sooty! I get it if you don’t want to reintroduce the separated oil back into the crankcase, then just have a catch bottle that you can drain after each flight.. or run it out to the tail like Extra 300s do.

 

[BonitaRV8]

If it was working fine up until 10 hours ago that means something changed. Have you added more oil recently? Any changes in how you operate the engine? Any negative Gs? Any changes in the engine monitor data you send to

If it was working fine up until 10 hours ago that means something changed. Have you added more oil recently? Any changes in how you operate the engine? Any negative Gs? Any changes in the engine monitor data you send to Savvy?

Yes I am consuming a little more oil now but the increased consumption corresponds with the accumulation on the belly. I don't think I am burning it and don't think I'm getting any blowby. The first 80 or so hours on the engine I hardly added any oil and there was no oil coming out of the breather tube. I'm scratching my head because the oil hose returning to the engine is dry but I have oil exiting the breather.

I don't have an inverted oil system so I never pull negative Gs. I do fly LOP when cruising.