Mooney M20E oil consumption

[Celso Backes]

I just bought a Mooney m20e and it is consuming a lot of oil.   It had a oil change and then I flew for 1.2 hrs and it consumed 3qtr of oil.   The compression are all in mid 70's and it flew fine with no problems.  It did have a new cylinder put in it this past August and has flown about 6hrs on that new cylinder.   It burned a lot of oil on the ferry flight from Tx to Alabama.  Does anyone have any suggestions. 

[Tim Jodice]

Are you sure it is burning it and not throwing it out the breather tube?

[aaronk25]

With that much oil it would be very noticeable on the exhaust of the culprit cylinder.

The plugs would be very oily too. If it’s getting past the rings, remember so is the hot exhaust gases which shorten camshaft and lifter life as well as they are directly in the path. There only splash lubricated.

But that’s a lot of oil. Are you sure it’s really that much? Was the oil level checked after running the engine for a while after oil change and then re checked when done with the flight?

Again, that’s a lot of oil, like enough to leave a blue cloud behind you. Time for a and p mechanic to inspect.


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[Tcraft938]

First and most important, I'm not an A&P/IA.  When you say it used 1.2 qts, what was your starting point at the oil change.  For example, was the full 8 qts put in?  If so it is not unusual for them to throw out oil quickly and then stabilize between 6 and 5 qts, then stay there for several hours.  If you started your flight with say 6 qts and ended a short time later with around 4, that indicates a different story.  Also it sounds like you are breaking in a cylinder, what oil are you using?  Mineral Oil?  Multi or mono grade?  Usually to break in cylinders, most shops tell you to run it pretty hard, no less than 75% and plenty rich to seat the rings.  You do this until oil consumption has stabilized.  Six hours of flight since August is not very much.  My AP would be telling me, "try to fly it at least once per week, no less than one hour per flight, run it hard, keep it cool in the climb and no touch and goes".  It would likely have mineral oil in it (maybe not for you since it is just one new cylinder) and we would change the oil at 10 hours.  

[takair]

21 minutes ago, Celso Backes said:

I just bought a Mooney m20e and it is consuming a lot of oil.   It had a oil change and then I flew for 1.2 hrs and it consumed 3qtr of oil.   The compression are all in mid 70's and it flew fine with no problems.  It did have a new cylinder put in it this past August and has flown about 6hrs on that new cylinder.   It burned a lot of oil on the ferry flight from Tx to Alabama.  Does anyone have any suggestions. 

3 quarts in 1.2 hours is excessive, even if you started at 8 quarts.  Start by looking at the spark plugs to see if you can identify one with excessive oil in the plugs.  It would be helpful to know the history of the aircraft.  Did it sit for extensive period or did the owner fly it regularly?  Can you contact them for history?

[Matt Ward]

I'm the farthest thing from a mechanic, but...

If you don't see it coming out the breather, in the exhaust, and not overly evident on the belly, check the gasket covers.  You'll  need to remove the wings and probably the top cowling but rub your finger around them and see what you find.  If the gasket covers are not the orange ones, if they're the cork ones, consider replacing them.  Also while you're in there rub your finger around the filter and look for excess oil - double check the safety wire too.  Just near the filter you'll see the prop governor (I think) and check for oil there too.  If you see much in that part of the compartment take it very seriously.

[Skates97]

Another question is how long after the flight did you check the oil. If you are checking it right after shutting down it is going to show much lower as the oil hasn't all drained back down into the pan yet. If you check it right after a flight and then go back alter you will see the difference.

[Celso Backes]

50 minutes ago, Tcraft938 said:

First and most important, I'm not an A&P/IA.  When you say it used 1.2 qts, what was your starting point at the oil change.  For example, was the full 8 qts put in?  If so it is not unusual for them to throw out oil quickly and then stabilize between 6 and 5 qts, then stay there for several hours.  If you started your flight with say 6 qts and ended a short time later with around 4, that indicates a different story.  Also it sounds like you are breaking in a cylinder, what oil are you using?  Mineral Oil?  Multi or mono grade?  Usually to break in cylinders, most shops tell you to run it pretty hard, no less than 75% and plenty rich to seat the rings.  You do this until oil consumption has stabilized.  Six hours of flight since August is not very much.  My AP would be telling me, "try to fly it at least once per week, no less than one hour per flight, run it hard, keep it cool in the climb and no touch and goes".  It would likely have mineral oil in it (maybe not for you since it is just one new cylinder) and we would change the oil at 10 hours.  

I started my flight with 7qtr and end my flight with 4

[Celso Backes]

57 minutes ago, Tim Jodice said:

Are you sure it is burning it and not throwing it out the breather tube?

it is not dripping any oil in the hanger 

[Celso Backes]

38 minutes ago, takair said:

3 quarts in 1.2 hours is excessive, even if you started at 8 quarts.  Start by looking at the spark plugs to see if you can identify one with excessive oil in the plugs.  It would be helpful to know the history of the aircraft.  Did it sit for extensive period or did the owner fly it regularly?  Can you contact them for history?

it only flew last year for 9hrs and then sat a good bit of the time...

[bmcconnaha]

to determine oil consumption i check the oil with the conditions as close to the same as possible... same spot in the hangar, engine preheated for a few hours.  i try not to get too concerned checking it on the ramp after shutdown, there are too many variables, level surface, oil still up high in the engine etc

[mike_elliott]

If its blow by you will find your missing 3 qts on the belly, If it is a bad oil ring or valve guides, you will find soot evidence in the exhaust pipe. Any more than 6 qts in an io360 typically finds its way to the belly within an hr

[bonal]

That much oil in that short time has to be an indication on where it went. Start looking in the obvious places exhaust, plugs, belly, pilot side means breather tube. All zero cost to do. Also try compression check but instead of looking for a number listen through the oil fill tube when each cylinder is pressurized for sound of passing air.  I don't think it possible to leak that much and not find it reach the floor. 

Good luck, and a good reminder to all how important to check oil every time before starting the engine even after a short flight 

[Ragsf15e]

Ok, if you measured it at 7qts, flew 1.2, landed, and measured 4qts, then it definitely did not burn 4 qts.  As @Skates97said, you’ll have to wait at least 4 or 5 days for it to run back down.  It’s a noticeable difference for sure.  Now mine will drain back down and show about 1/2 to 3/4 qt higher after 5 days, so if yours is similar, you’re still burning a lot of oil.  Maybe 2.5qts in an hour?  That’s a lot.  If it was a leak, you’d have oil spilling out all over the cowling.  I’d still open the cowl and look around.

More likely it’s being blown out the breather or burned.  At 6 hours, you’re still breaking in that new cylinder, right?  Mineral oil and flying at 75% power or more, limited ground ops, no extra patterns, etc?  Because if that cylinder isn’t broken in properly, you’re setting yourself up for future problems with lots of oil use.  Not breaking in the cylinder could be part of the problem.  They use more oil during break in. You should read the lycoming break in guidance very closely.

Last, what type of cylinders are they?  Chrome? Steel?

[Celso Backes]

39 minutes ago, bmcconnaha said:

to determine oil consumption i check the oil with the conditions as close to the same as possible... same spot in the hangar, engine preheated for a few hours.  i try not to get too concerned checking it on the ramp after shutdown, there are too many variables, level surface, oil still up high in the engine etc

i checked two days after the flight...

 

[Celso Backes]

15 minutes ago, Ragsf15e said:

Ok, if you measured it at 7qts, flew 1.2, landed, and measured 4qts, then it definitely did not burn 4 qts.  As @Skates97said, you’ll have to wait at least 4 or 5 days for it to run back down.  It’s a noticeable difference for sure.  Now mine will drain back down and show about 1/2 to 3/4 qt higher after 5 days, so if yours is similar, you’re still burning a lot of oil.  Maybe 2.5qts in an hour?  That’s a lot.  If it was a leak, you’d have oil spilling out all over the cowling.  I’d still open the cowl and look around.

More likely it’s being blown out the breather or burned.  At 6 hours, you’re still breaking in that new cylinder, right?  Mineral oil and flying at 75% power or more, limited ground ops, no extra patterns, etc?  Because if that cylinder isn’t broken in properly, you’re setting yourself up for future problems with lots of oil use.  Not breaking in the cylinder could be part of the problem.  They use more oil during break in. You should read the lycoming break in guidance very closely.

Last, what type of cylinders are they?  Chrome? Steel?

I checked it two days after the flight.

 

[Ragsf15e]

3 minutes ago, Celso Backes said:

I checked it two days after the flight.

 

Ok, so that’s good.  Likely if there’s not a noticeable leak then not breaking in that cylinder properly/fully is part of the problem.  Stabilization of oil useage is one of the signs that break in is completed.  Again, you should go through the lycoming break in guidance.

Be careful though because that is considerable oil burn.  You should be flying near airports, doing the break in engine management, but not patterns or low power operations.

[DXB]

 If it's not an oily mess under the cowl and there's not oily residue at the tailpipe, then it's blowby coming out the breather.  The belly should be very messy. Compressions can be deceptively ok in this situation. That's certainly enought oil consumption to ground it. A new cylinder that's not broken in won't give you THAT much extra oil consumption.   Could be broken compression ring(s) and/or stuck oil control rings. Oily bottom plug(s) may give a hint as to offending cylinder(s). Scoping cylinders to find pooled oil and/or deep scuffs on the walls may also guide which cylinder(s) to pull first.

[David Lloyd]

Just like everyone else, several quarts in 1.2 hours is gonna leave evidence.  A big puddle under the airplane or oil dripping from the belly or oil exhaust and plugs.  If the latter, are the plug oily on all cylinders or just the cylinder that was replaced?  With only 6 hours or so, that cylinder is not broken in yet and will use more oil, but this sounds excessive.  What oil is being used?  In the 1.2 hours, were you running it hard to break in the cylinder?

I would hesitate on flying until you do a bit of detective work and figure where that oil exited the engine.  

[hammdo]

If the oil was changed before you bought it, I'd change it again to mineral oil and new filter - just to be certain. I would be checking for oil leaks but if no puddles are found, may have a glazed cylinder or one not broken in.

I flew mine over the airport - 500 ft above pattern altitude for at least an hour - 75% power . Landed, checked oil, added what was needed. Flew it again. 

May need a borescope to see if the cylinder is glazed. Check leak down too (pressure cylinder and as others have said, ck oil filler are and exhaust for air leaks).

-Don 

[Guest]

Just my opinion, but a new cylinder or cylinders or newly overhauled engine just don’t use that much oil.  Pull all of the spark plugs and look for very black plugs and oily cylinders.  Something is wrong in one or more of your cylinders.
 

Clarence

[carusoam]

Brief summary...

1) Good to ask questions, because something isn’t right about that much oil evaporating...

2) Breaking in a new cylinder follows a process.... and a particular oil... make sure you are following the process...

3) typical  places oil goes or hides...

• Blow-by... exhaust foaming the oil, and pressing it out the case vent... find the case vent.  It will be at the head of a giant mess... the oil will turn black after a few hours and smell like exhaust...
• Check the tail tie-down... if oil is dripping off it... it takes a lot of oil to get one drop hanging off the tie-down...
• Check the oil return lines by the valve covers... these have small hose clamps that can be ancient and failed....
• A quart can usually hide up inside the engine and prop... wait at least overnight to see how much returns to the sump...
• Over filling the sump throws a quart out the vent fervently...
• Exhaust pipe... usually dry, sometimes dusty with exhaust by-products... sludgy or oily? Not right.
• bottom plugs... expect one to be oily enough that if you have an engine monitor... the plug may not be firing properly...
• Dental cam down the spark plug hole can be helpful...
• May have surface issues in the cylinder(s)
• May be missing an oil control ring...
• Case cracks, case seals, loose filter, loose screen, any oil in the cowling...?
• There has got to be an a oil drip somewhere... and a lot more where you find that one...

4) If you can’t find three quarts of oil that have gone missing... get ready for an inventory analysis... 

5) Start with six quarts, clean belly pan, clean windshield, clean tail tie-down, clean case vent, clean cowl bottom...

6) leaking that much oil, is not a stable reliable amount... be careful, it can leak even faster... the next time...

7) Got a go pro? Mounted on the tail, it can sense oil faster than you can taxi to the run-up area...

8) Don’t be distracted by the one cylinder... it may be more than one, or could be something completely different...

 

PP thoughts of what is reported above...

Good luck with your next steps...

Best regards,

-a-

[PT20J]

Just for reference

[Celso Backes]

On 11/17/2020 at 12:43 PM, Celso Backes said:

I checked it two days after the flight.

 

steal cylinders current update cylinder #4 has oil on the plugs alot of oil.  so need rings and going to get it done and see what happens It was checked a week latter and it shows 3qtr went somewhere most likely #4 burned it up.   compressions are good all between 72 and 78

[Celso Backes]

On 11/17/2020 at 11:57 AM, bmcconnaha said:

to determine oil consumption i check the oil with the conditions as close to the same as possible... same spot in the hangar, engine preheated for a few hours.  i try not to get too concerned checking it on the ramp after shutdown, there are too many variables, level surface, oil still up high in the engine etc

 

On 11/17/2020 at 11:27 PM, PT20J said:

Just for reference

.64 qtr an hr