Increased Oil Consumption

[RVG8tor]

I recently had an increase in my oil consumption after installing the ASA oil separator. I have done and extensive check of the system and feel confident that the separator is not my problem. It was the first thing I checked since the consumption started after it's installation. With my stock breather tube set up I would always get a bit of post flight drip onto the exhaust pipe and I had some weep spots on the sump gasket as well and something near the top of the engine, I would get drips on the Filter Air Box. I love the separator because all of these weeps have stopped.

After confirming the separator is not my issue I performed a compression check on the warm engine and they are all 79/80 or better. I used a dental camera to look into the cylinders, the only thing that seems odd is on two cylinders #2 & 3, the intake valve has a damp spot, this must be from oil but I don't know what to do about this or where it might be coming from.

My oil consumption was around 10 hours per qt. With this oil change it has dropped to 6.2 hours per qt.

Pictures follow, sorry about the black splatter in the pictures, the dental camera was damaged by me as I cut off the plastic case to mod it to fit in the spark plug holes.

Under the bottom of the intake valve is goo like burnt oil, that is picture two.

I have normal exhaust color, is is gray white with a dry feel. So I don't think oil is getting past the rings. I don't understand the intake anatomy enough to know what might be happening under the valve covers, I am obviously trying to learn more now.

I appreciate any words of wisdom. Oh I keep oil level at 6 Qts, engine is a TMX IO-360 with AFP injection, dual P-Mags with Auto Plugs, the plugs are all nice a clean, mag checks are good but I have not done a mag check at altitude in a couple months.

Cheers.

 

[DanH]

I installed the ASA separator and have had an increase in oil consumption.

Pull the hose off the check valve at the exhaust. Look inside the hose and into the check valve. Are they oily?

Unscrew the check valve from the exhaust pipe tap. Look into the exhaust pipe tap. Is it clean and open, or is there a buildup of solid material?

 

[RVG8tor]

Wilco

Pull the hose off the check valve at the exhaust. Look inside the hose and into the check valve. Are they oily?

Unscrew the check valve from the exhaust pipe tap. Look into the exhaust pipe tap. Is it clean and open, or is there a buildup of solid material?

Thanks Dan I will do this!

Cheers

 

[RVG8tor]

Seperator not the issue

Pull the hose off the check valve at the exhaust. Look inside the hose and into the check valve. Are they oily?

Unscrew the check valve from the exhaust pipe tap. Look into the exhaust pipe tap. Is it clean and open, or is there a buildup of solid material?

I checked out the parts you pointed out and all was normal. Hose to the reed valve was clean and open. I also made sure the return fitting on the seperator was open. Allen at ASA gave me some things to check and it appears the seperator is not my issue.

I did a compression check today and I have the same numbers as I had back in November, all cylinders 79/80. Plan to cut open the oil filter to see what it holds. I plan to post some photos of inside cylinders, but I have two that have wet spots on the intake valves, yet my plugs are nice ad dry and no fowling. Mystery!

 

[Mike S]

Mike, how much oil do you usually run in the engine????

 

[DanH]

I checked out the parts you pointed out and all was normal. Hose to the reed valve was clean and open. I also made sure the return fitting on the seperator was open.

And tried to blow through the check valve both ways?

Allen at ASA gave me some things to check and it appears the separator is not my issue.

Probably true. We're all learning details as we go, but I would think a quart in 3 to 5 hours would show oil in the outlet hose and valve, if oil was passing through the separator with the outlet flow. I dunno, maybe it would not be obvious. There are ways to make it obvious.

In any case, there are only two paths for oil consumption...oil out the pipe or oil into a cylinder. I can't think of a separator failure mode that would move oil into a cylinder, and that includes positive pressure. The old Walker AirSep (now sold by Airwolf) pressurizes the case.

BTW, tell us the things Allen had you check.

 

[RVG8tor]

Checks done on seperator

And tried to blow through the check valve both ways?



Probably true. We're all learning details as we go, but I would think a quart in 3 to 5 hours would show oil in the outlet hose and valve, if oil was passing through the separator with the outlet flow. I dunno, maybe it would not be obvious. There are ways to make it obvious.

In any case, there are only two paths for oil consumption...oil out the pipe or oil into a cylinder. I can't think of a separator failure mode that would move oil into a cylinder, and that includes positive pressure. The old Walker AirSep (now sold by Airwolf) pressurizes the case.

BTW, tell us the things Allen had you check.

I removed the hose to the reed valve then removed from the exhaust. The I checked the valve by blowing and sucking air and it worked one way as designed. the inlet the valve was clean, the out let had a light milky film like you get if you mix water into oil. The hose was clean and no blockage.

Allen had me take of the inlet hose to the separator and the oil return line. Then I blew air into the separator inlet and made sure that air came out both the return line fitting and the port to the exhaust. The return line fitting has a retrictor built into it this test makes sure there is nothing blocking the small hole. All of this checked out fine.

One thing I did ask, since in my early stages of doing loops I unloaded to zero G and left a half quart of oil on my belly (before separator) I wondered how the separator would handle a big slug of oil like this. Basically once the separator is half full, about a cup I think he said it would just port out the exhaust exit from the separator. Allen said if this becomes a problem, installing the larger separator which can hold more oil before porting over board would help. I don't have issues with this since I now have a feel for aerobatics in the RV and don't ever get to zero G anymore, of course I still have to try the hammerhead which I will do when I can get up with a friend in his Pitts S2B!

So my issue is separator good, no oil in exhaust, nice gray powder inside the exhaust tubes. I ran the last flight ROP and when I did the compression check I looked inside the cylinders and there was no oil puddles like the last time I looked. I had been running LOP fairly aggressively but only flying around 2000' (I like burning only 6.7 gph), I wonder if that might cause more oil consumption? Engine runs like a top, I could use a nozzle tune on #2 as it is the first to peak and gives me a GAMI spread closer to .5-.7 depending on how well I do the test.

Plan now is to fly it and make detailed check of the oil the same way every time and confirm that I did not create this issue myself. I don't think that is it since I had the numbers from my last oil change (less than 20 hours ago) and how many quarts I added, that gave me a burn rate of 6.2 hours per Qt.

Cheers and Thanks for the help.

 

[flightlogic]

Nemo, excellent report. Great attention to detail, appreciate the post.

 

[RVG8tor]

Missed post

Mike, how much oil do you usually run in the engine????

Sorry Mike I missed your question. I put in 6 qts at the oil change and let it go down to 5 before I top it back up to 6.

Cheers

 

[Mike S]

OK, got it.

I was wondering if running the oil to full capacity might be causing enough splash/spray/mist to overwhelm the separator.

Sounds like this is not the case.

 

[RVG8tor]

Self induced

We'll I did the full inspection of the separator, oil change and analysis, compression check etc. I have flown almost 7 hours and the oil level has hardly moved.

I can only surmise that my high oil consumption was self induced. I do some aerobatics often but have not gone negative in a long time. I do go to .5 G on occasion to gain energy or to make a roll look better. This must have been enough to make me exceed the capacity if the oil separator and dump some out the exhaust valve.

I have avoided aerobatics on purpose to see how the oil consumption would track, it appears fine.

Just wanted to close out this issue for anyone who finds this on a future search.

Cheers

 

[Mike S]

Just wanted to close out this issue for anyone who finds this on a future search.

Cheers

Good of you, I wish everyone would do this.

 

[DanH]

Good of you, I wish everyone would do this.

+1...good man Nemo.

Noticed something in a previous post that I didn't know. The separator's oil return outlet (out to the crankcase) has a restrictor fitting? How large is the bore?

 

[RVG8tor]

Not sure

+1...good man Nemo.

Noticed something in a previous post that I didn't know. The separator's oil return outlet (out to the crankcase) has a restrictor fitting? How large is the bore?

The restricter is built into the seperator, I think Allen said it is around 1/8".

Cheers

 

[PerfTech]

We'll I did the full inspection of the separator, oil change and analysis, compression check etc. I have flown almost 7 hours and the oil level has hardly moved.

I can only surmise that my high oil consumption was self induced. I do some aerobatics often but have not gone negative in a long time. I do go to .5 G on occasion to gain energy or to make a roll look better. This must have been enough to make me exceed the capacity if the oil separator and dump some out the exhaust valve.

I have avoided aerobatics on purpose to see how the oil consumption would track, it appears fine.

Just wanted to close out this issue for anyone who finds this on a future search.

Cheers

....I guess I should have told Mike this earlier as it could have possibly saved him some work, but it slipped my mind. Should anyone else experience a similar issue and think it may be attributable to an aerobatics issue. Have a friend in another aircraft observe a maneuver, paying particular attention to the exhaust. If oil is exiting the engine in this manor, you will see a large poof of smoke from the pipe, just like a smoke system. This will verify the breather system as the culprit should it be the case. Thanks, Allan....