Oil Breather Tube
I have a 1977 Archer that is using oil to the tune of 3 to 4 quarts per hour. Most of that appears to be going out the breather tube. So I was wondering if there is a dimension that the breather tube should be sticking out from the bottom of the fuselage, not the bottom of the cowling? Thanks in advance for any help anyone on this form can provide!
Comments
Two things...speaking from experience. 1) Does the oil level stabilize at some point...Both my PA28 235C and Lance II would blow oil until a certain level it was happy with...The Lance with a 12 qt capacity would blow everything until the 9 qt level and would stay there until oil change...2) Blow by from the rings pressurizing the crankcase...that would push the oil out...
Would like to know if the oil level stabilizes at some level...
Roe
Same with me. Full capacity ends up evacuating out several qts. On my T Lance, filling to 12 is a recipe for a greased belly. Fill to 9 and it’s clean. On my previous archer, it was less of an issue but it still would not take a full oil pain without spitting out a quart of two. The Arrow is taken Care of by the owner and I just push the gas and pull back. MX is not my concern.
I own and fly a 79 PA32RT-300T. Previous aircraft are a 79 Archer and 76 Arrow.
Before the engine was overhauled some years ago, it would barely use any oil whatsoever. After the overhaul and break in, it seems to it be using more than it should. I will allow it to go below the 6 quarts I normally like to keep the oil level at and see if it's stabilizes at a lower level. I'll let you know what I find out. Thank you very much!
5 quarts is the magic number in my Arrow.
Scott Sherer
Wright Brothers Master Pilot, FAA Commercial Pilot
In my Continental TSIO360, the oil cap has a gasket. I would lose oil out the breather down to below 6 qts. Replacing the gasket resulted in a very snug (almost too tight) oil cap. My oil capacity is stable at oil change (7.5 - 8 qts) and "burns" only 1 qt in 20 hours. Very little oil lost out the breather tube.
My theory is that a loose oil cap allows the air pressure above the engine in flight to find its way past the oil cap, partially pressurizing the crankcase and pushing oil out the breather. A high oil level would require a small amount of pressure to send it overboard; a lower oil level would require more air pressure. The stable oil level might depend on how loose the oil cap is and on the specific ram air pressure. Again, just my theory, though fixing the oil cap fixed my oil overboard issue. YMMV.
DJ
Breather should not be subject to suction below the cowling. IF you are really missing that much oil on a 1hr flight, i suggest grounding unitill a reason is found.. Compresion checks, oil and filter check, if the oil smells burnt, you may have stuck broken ring (s). Yes, poor crank seal could cause. no on the dipstick on this plane. you are loosing 1/2 your capacity, time to investigate. carl
48 yrs A/P IA DAL aircraft inspector. 172N
Just another data point. I don’t add unless I’m below 5qts. Very little oil consumption, I’ll normally add 1qt between oil changes. O-360 ~400 SMOH
Jeremy Olexa, N2471U 1979 PA28-181 Archer II. Minneapolis, MN (KMIC)
This is a common complaint that I get for both Cessnas and Pipers. I disconnect the breather tube assembly at the engine fitting and coupling and flush it out with mineral spirits because sludge builds up in the tube, sometimes in the upper area and sometimes near the bottom. The problem with sludge is it forms a venturi which along with the airflow in flight begins to siphon oil. I suggest 1) clean the breather tube at least annually and 2) do not overfill the oil sump.