Head Scratcher...

R

RobertGerace

Guest
Ok. I'm scratching my head...

Since I've been running LOP, I too have experienced less oil usage...somewhere on the order of a quart every 4-7 hours.

What has me puzzled is the fact that (I run both engines at 9) and they will both show 9 after every flight. Then, about 4-7 hours later, the RIGHT engine will lose a quart in ONE flight.

I will put the one quart back in the right engine, and then on the very next flight (like CLOCKWORK) no matter how long the flight is, the LEFT engine will be down a quart.

This has happened about 4 or 5 times over the last month or so.

Is there any rhyme or reason to this?? I know I'm not dreaming...

Thanks!
 
Bob-

Is your oil consumption, overall, still similar to what you had running ROP?

Jeff
 
I was just reading this month's Light Plane Maintenance magazine.

They have a big article covering oil breather tubes. One problem they talked about is like you are describing, they called it "burping". If the tube is partially blocked or restricted, the engine builds up a little pressure and overcomes the blockage and suddenly, your oil level mysteriously drops on that flight. They have a lot of detail in the article about the routing and venting and uphill/downhill flow and how the lines work. The article indicated that even a restriction from a flat spot from a bad tubing bend can interfere with the low-pressure flow of crankcase gasses.

Might be worth checking out the breather lines, making sure they are clean, unrestricted and properly routed, scarfed and vented per your maintenance manual and whatever SB/SL's might apply to your plane.

So far, my newly overhauled O360 is doing great on the oil consumption.
 
I have the same scenario on my Continental IO-550. I run it at 11/12 qts. It stays there for about five hours and then suddenly drops to 10. If I don't fill it it stays at 10. No oil on the belly, it just disappears. I have talked to everyone, received a thousand different explanations, none of which make sense - 'it just happens' seems to explain it best. I would love to find out why.
I did have an oil breather blockage once on an IO-360 Lycoming in my Fuji. That blew out about 5 qts in an hour. The shop told me I had 'back compression', remove the cylinders, put on new rings, scored the pots, put it all back together whereupon it still blew out 5 qts on the test flight. An old grizzled mechanic who happened to be passing by said to check the breather tube. Lo and behold we found a blockage and the problem was solved. Legal action ensued over the $5000 bill and in the end the shop backed down. If your oil breather is blocked you will know it and it won't be intermittent.
Stephen.
 
RobertGerace said:
Ok. I'm scratching my head...

Since I've been running LOP, I too have experienced less oil usage...somewhere on the order of a quart every 4-7 hours.

What has me puzzled is the fact that (I run both engines at 9) and they will both show 9 after every flight. Then, about 4-7 hours later, the RIGHT engine will lose a quart in ONE flight.

I will put the one quart back in the right engine, and then on the very next flight (like CLOCKWORK) no matter how long the flight is, the LEFT engine will be down a quart.

This has happened about 4 or 5 times over the last month or so.

Is there any rhyme or reason to this?? I know I'm not dreaming...

Thanks!
Click to expand...

Might be due to variations in drainback and/or dipstick reading error (airplane not at the exact same attitude on the ground).

If you check the oil level right after shutdown and then periodically after that you will probably find that it takes quite a while for the last quart to reach the oil pan, and if so the readings you get the next time you fly may be quite dependent on how long it's been since the last flight. Also, I've found that I can get a quart difference in the reading on the dipstick if the plane is aft loaded enough to pitch it up a bit at rest.
 
Bonanza said:
I have the same scenario on my Continental IO-550. I run it at 11/12 qts. It stays there for about five hours and then suddenly drops to 10. If I don't fill it it stays at 10. No oil on the belly, it just disappears. I have talked to everyone, received a thousand different explanations, none of which make sense - 'it just happens' seems to explain it best. I would love to find out why.
I did have an oil breather blockage once on an IO-360 Lycoming in my Fuji. That blew out about 5 qts in an hour. The shop told me I had 'back compression', remove the cylinders, put on new rings, scored the pots, put it all back together whereupon it still blew out 5 qts on the test flight. An old grizzled mechanic who happened to be passing by said to check the breather tube. Lo and behold we found a blockage and the problem was solved. Legal action ensued over the $5000 bill and in the end the shop backed down. If your oil breather is blocked you will know it and it won't be intermittent.
Stephen.
Click to expand...

Stephen:

A lot of folks don't put more that 10 quarts in an IO-550. I haven't in my A-36TN since I've owned it. Ten quarts is what I fill to, and, believe it or not, if I put more in, it runs down to that number after a couple of flights. Don't know how it gets out of your plane without leaving a trace, but seems pretty common among owners of that engine. You will find the IO-550 can run pretty low and not have lubrication problems. Some factory tests show that with four or five quarts, it still lubricates well (not that you wish to try this). I fill to 10 and add a quart when below 9 and have never had a problem with oil pressure, oil temps and my oil analysis and oil filter inspections have been fine for over four years. On the Bonanza Net, it's quite common to find owners running 10 quarts on the 550. You might want to check with your mechanic. Mine thought it was fine, and I've asked a couple others.

Dave
 
RobertGerace said:
Ok. I'm scratching my head...

Since I've been running LOP, I too have experienced less oil usage...somewhere on the order of a quart every 4-7 hours.

What has me puzzled is the fact that (I run both engines at 9) and they will both show 9 after every flight. Then, about 4-7 hours later, the RIGHT engine will lose a quart in ONE flight.

I will put the one quart back in the right engine, and then on the very next flight (like CLOCKWORK) no matter how long the flight is, the LEFT engine will be down a quart.

This has happened about 4 or 5 times over the last month or so.

Is there any rhyme or reason to this?? I know I'm not dreaming...

Thanks!
Click to expand...

Gremlins get thirsty. Seriously, have you noted any correllation to the usage and altitude flown on that flight?
 
Henning,

No. It is just a matter of hours...after 6 or 7...the right engine is down a quart...after the next flight the left one is down a quart...I'm thinking there is something to the burping theory...
 
Dave Siciliano said:
Stephen:

A lot of folks don't put more that 10 quarts in an IO-550. I haven't in my A-36TN since I've owned it. Ten quarts is what I fill to, and, believe it or not, if I put more in, it runs down to that number after a couple of flights. Don't know how it gets out of your plane without leaving a trace, but seems pretty common among owners of that engine. You will find the IO-550 can run pretty low and not have lubrication problems. Some factory tests show that with four or five quarts, it still lubricates well (not that you wish to try this). I fill to 10 and add a quart when below 9 and have never had a problem with oil pressure, oil temps and my oil analysis and oil filter inspections have been fine for over four years. On the Bonanza Net, it's quite common to find owners running 10 quarts on the 550. You might want to check with your mechanic. Mine thought it was fine, and I've asked a couple others.

Dave
Click to expand...
Dave, Thanks for that. I went down and checked the plane out today, ready for tomorrows flight to Texas. It is down on 10 qts so rather than fill it, I have left it that way and will see what happens on the trip. I am going to be flying something over 20 hours in the next week so should get a good idea. I'll report back when I get home.
Stephen.
 
Hope that helps you. I have an oil seperator and very seldom use a quart between 25 hour oil changes. But, if I fill it over 10 gallons, I use one right away. Make sure you talk to your mechanic or look at the POH to see what the minimum oil requirement is.

Dave
 
My TSIO-520B's will pump out anything over 9 quarts. When it comes time to be down a quart, it will be EXACTLY one quart lower on the next flight -- regardless if the leg was 30 minutes or 4 hours.

So, I make sure it is at 9 before I take off. No more and no less.
 
RobertGerace said:
Henning,

No. It is just a matter of hours...after 6 or 7...the right engine is down a quart...after the next flight the left one is down a quart...I'm thinking there is something to the burping theory...
Click to expand...

Well, if it's burping, you'll see it somewhere. Do you have an Airsep on your breather line? Another thing to check is the exhaust stack. Turbo seals do not keep oil in, they keep exhaust gas out. My turbos used to drain back all the oil in the line above out the turbo after shut down until I put the check valves in. Gremlins though, are still my #1 suspect.
 
Bob, I'll see if I can scan the article in somehow. It's in the most recent copy of Light Plane Maintenance, lots of detail and photos and so on. If you know someone locally who subscribes, it would be worth it to borrow a copy and see if it applies to your plane.
 
Larry,

Actually, I subscribe to that, but I'm behind in my reading...sigh...

THANKS!
 
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