201 OIL CONSUMPTION

[FAST FLIGHT OPTIONS LLC]

All-

Within the past year i purchased a 1980 Mooney M20J 201...I would like to query the 201 owners on this forum to determine the following:

1) How many quarts of oil  do they routinely operate their engines with?

2) How much oil/sediment do you all find on the underside of the cowling/fuselage after say a 2HR X-Country Flight?

I wash my plane and then fly it for a while and find an oily grease like substance on the exterior side of the nose gear doors and the belly of the aircraft when I return.  It's worse on the nose gear doors then the belly of the aircraft but at this point I dont feel there is no sense in washing it off because it happnes after almost every flight.

I tried operating the engine with 5 quarts of oil as opposed to my normal 6 quarts to see if this would help but the oil seems to still be appering.  Also after taking off with 5 quarts of oil today and flying for 2 hours I landed to find 4 quarts of oil on the dip stick after I let the engine cool down.  Trying to figure this out is getting frustrating!

Engine oil temps seems to be holding steady in the normal operating range but  I was wondering if I'm dealing with an oil leak of some sort. The oil pressure is indicating on the very low side of normal but I figure that's because I'm taking off with 5 and landing with 4 quarts of oil two hours later.

My mechanic looked at it at the last oil change and said the blowing of oil onto the bottom of the plane is normal but I'm inclined to disagree with him at this point in time.  I also considered the fact that the eninge was buring the oil up in addition to blowing it out but I really dont think that's what's happening in this case either since the engine only has about 400 HRS on it and always runs pretty smooth and always within normal operating parameters.

Anyone have similar experiences?

Thanks

Nick

[Cruiser]

It takes very, very, very little oil to coat the bottom of the plane. The oily film mixed with a little dust and it looks much worse than it really is volume wise. Comes off quite easily with a little Super Clean spray and paper towels.

I clean the bottom of my '84 M20J about every 10hrs. Trying to keep the oil level between 6½qts and 6 qts. cold. I will add ¼qt. or ½qt. at a time. Normal consumption on my 200 SFREM is about 1qt/20 hrs. right now. It really depends on how hard you run the engine. Normally 2400 or 2450 RPM. Higher will use more oil. Oil temp on the JPI is in the 180°F range.

Plugs are clean and no fouling so most of the oil loss is out the breather tube in the pilot side cowling flap. This is confirmed by the dripping of oil from that tube into a cup lined with paper towel on the hangar floor below it. There are no engine leaks.

[FAST FLIGHT OPTIONS LLC]

WOW 1 Qt every 20 HRS...I dont even come close to that!

[Piloto]

Mine is about 18hrs/qt on 300hrs SMOH when topped to 8 qts. I have an M20 oil separator that appears to work good.

I would recommend it to keep the belly clean and reduce the oil compsumption. Also check the color of the exhaust stain. If not burning oil the color should be yellowish. If the engine is burning oil the color is dark brown or black. If it appears that is burning oil check the routing of the cranck case breather line. Check for kinks and holes on the line. The line should be vented aft to create a suction effect. The suction helps keep the oil from getting pass the piston rings into the combustion chamber.

Check inside the cowling and engine for oil stains. You may have an oil leak that could be part of your problem.

José 

[GeorgePerry]

As for Oil burn rates, the maximum allowable oil consumption limits for all Textron Lycoming aircraft engines can be determined by using the following formula:   .006 x BHP x 4 / 7.4 = Qt./Hr.

For a 200 HP engine that works out to about 0.64 Qt's per hour or  slightly more than one quart every two hours.  That's ALOT of oil to burn in only two hours.  Actual numbers vary but "average" oil burn for a I0-360 should be about 1 quart every 3 - 6 hours if the engine's tight.

Some folks who don't have an oil/air separator run with between 6 and 7 quarts to keep the crank vent from pumping out excess fluid on to the belly.  However - I would NEVER run a 200 HP IO-360 engine with less than 6 quarts of oil.   Flying with only 4 quarts is asking for trouble.

 

[RJBrown]

At 1750 hours on the engine it still runs right. I top to 7 qts and add at 6. takes 3-5 hours to need oil. And yes the belly does get a bit oily.

[OR75]

1qt every 2 hours is a lot considering you can conceptually fly a J with standard fuel tank close to 6 hours

I had at some point a lot of oil (yellow) on the gear doors.   I suggest you ask your mechanic to check the 4 small rubber tubes that are under the crankcase.  These 4 tubes can become a bit loose. They are kept with clamps and need to be tightened (8 clamps, 2 for each rubber tube).   I don't have a picture and my mechanical knowledge is limited. May be someone on here will chime in to describe what those are. They are a pain to reach but easy to locate maybe with a flashlight !

After tightening the clamps, I have a lot less oil on the gear well.

Hope this helps.

 

 

 

 

[carusoam]

Nick,

Oil can be burned, leaked, or vented...

[1] Leaks...

I believe the tubes that OR75 is referring to are the oil return lines from the valves back to the oil pan. 

It is a good observation, many a drip can originate from these small hose clamps.  Another drip source is the quick change oil valve at the bottom of the oil pan.  These can get old and drip too. Old valve covers leak through their old style cork seals.  Evenly tightening these old screws can stop the leaks.  Have your mechanic update cork seals for the new silicone style.

Take a good look at the back of the engine where the magnetos and oil screens are.  Serious oil leaks can be found here...

Some cases leak between halves.

These are all accesible through the side panels or removing the top of the cowling.  Oil leaks usually will leave a tell tale mess inside the cowling.  I am pretty sure the floor of the cowl should be clean unless oil is dripping in there.

Q: Is it clean inside the cowl?

[2] Burned

I concur with Piloto on how to determine if the oil is burned by inspecting the exhaust residue in the pipes.  If oil is exiting through the cylinders, it will show up in the exhaust pipes and on spark plugs.

Q: Is oily black material showing in the exhaust pipe?

[3] Vented

Is there a way to measure how much gets vented without investing in expensive recovery equipment?  I saw an experimental with a plastic bottle at the end of the case vent.  (I don't believe this would work for a Mooney).  Vented oil leaves by the vent tube that has it's end overboard.  Vented oil does not appear anywhere inside the cowling.

When checking for proper venting.  The vent tube should have a small hole near the engine.  This allows venting in the event the vent tube gets blocked (by ice).

 

[4] Observations

I found that long climbs at high power pushed alot of oil overboard in my O360.  1 qt every 5 hours, and it seemed like alot for an engine with 1,200 hrs SMOH.

Best regards,

-a-

[FAST FLIGHT OPTIONS LLC]

Yes afTER READING POSTS ABOUT IT ON THIS SITE I STARTED TO USE CAM GUARD  JUST ABOUT HALF A QUART AT OIL CHANGE TIME  ALSO NOW THAT I THINK ABOUT I NOTICE MORE OF AN OIL LOSS DURING WOT CLIMBS TO BETWEEN 9 AND 11 K FEET AS SOMEONE MENTIONED   IM AWAY FROM HOME BUT WHEN I GET BACK ILL EXAMINE THE EXHAUST COLOR A BIT MORE CLOSELY  

[Piloto]

Quote: carusoam

 

[3] Vented

Is there a way to measure how much gets vented without investing in expensive recovery equipment?  I saw an experimental with a plastic bottle at the end of the case vent.  (I don't believe this would work for a Mooney).  Vented oil leaves by the vent tube that has it's end overboard.  Vented oil does not appear anywhere inside the cowling.

When checking for proper venting.  The vent tube should have a small hole near the engine.  This allows venting in the event the vent tube gets blocked (by ice).

 

 

Best regards,

-a-

[OR75]

A suggestion to detect where the leak is coming from:

Remove cowlings and clean the engine as well as you can under the supervision of your A/P.

run the engine a little bit but do not fly it ...  taxi to the other side of the field to get gas or whatever.

open the cowling again and look ...

 

 

 

 

[Magnum]

Quote: GeorgePerry

As for Oil burn rates, the maximum allowable oil consumption limits for all Textron Lycoming aircraft engines can be determined by using the following formula:   .006 x BHP x 4 / 7.4 = Qt./Hr.

For a 200 HP engine that works out to about 0.64 Qt's per hour or  slightly more than one quart every two hours.  That's ALOT of oil to burn in only two hours.  Actual numbers vary but "average" oil burn for a I0-360 should be about 1 quart every 3 - 6 hours if the engine's tight.

Some folks who don't have an oil/air separator run with between 6 and 7 quarts to keep the crank vent from pumping out excess fluid on to the belly.  However - I would NEVER run a 200 HP IO-360 engine with less than 6 quarts of oil.   Flying with only 4 quarts is asking for trouble.

 

[N201MKTurbo]

My engine uses no oil. I rerely add a QT between 50 hr oil changes, yet it leaks enough to make the engine, gear doors and belly an awful mess.

Except in extream leakage situations you cannot equate consumption with messiness.

I was told in engine school that the purpose of oil in an engine is to cool, clean and lubricate the engine. After years of airplane ownership and maintenance I have determined that the purpose of oil in an engine is to get out by any means possible!

I was told once by an old pilot that airplanes are like dogs.... they like to mark their territory.

[ProprAire]

My '77 J (400 hrs SFOH) had leaky engine carry through bolts that my mechanic addressed with a quick fix during the annual.  Prior to that, I was also wiping oil off the the gear doors and dealing with a greasy belly pan.  Since the annual, oil consumption is about 1 qt for every 3-4 hours flown.  I cruise at 2500 RPM and never fill above 6.5 qts.  Anything more and I'm seeing oil dripping out of the breather tube. 

Dan

N201NX

[Sabremech]

Another good way to find small oil leaks is to use a black light. Clean the engine, run it for 5 minutes or so then look it over with a black light and the oil will glow giving a good idea where the leak is. Has worked well for me a number of times.

[jlunseth]

I have been going through a similar things with my 231.  I fly in the high teens/low flight levels quite a bit.  My oil usage when I fly in the 6000-9000 range is negligible, but when I perform a WOT climb to get to say FL200, the plane blows out quite a bit of oil.  When I am regularly flying in the lower altitudes I keep about 6 qts. in the engine and can go a long time without adding anything.  When I do the WOT climbs, I follow the instructions in the manual to fill the engine to 8 qts. to avoid winding up at the end of a long flight with low oil.

[Andries]

I 've been reading several posts on oil consumption. I am quite fed up with my M20J, 1980 model. It was running hot, so I had it checked at an AMO, kept it for 2 weeks and 50 000 later it was "fixed"... Replaced the verna therm, changed timing on magnetos, changed the oil pressure etc etc. 100 hours later, I was still not happy. Next AMO said cylinders was cracked. Replaced all 4, another 70 000. Flew it for 15 hours to seet cylinders, balls to the wall low level, still using excessive oil. Every 2 hours more than a bottle, 1litre! Took it back, they opened it, cam was full of "pitts", whatever that means. Another 6 weeks, new cam, gears etc etc, another 85 000! To put it together at the AMO, another 25 000. So now we are at balls to the walls again, it is now 17 hours, I fill it to 6, fly 2 hours, it is on 4. This happens every 2 hours. When is the oil supposed to settle? We are at quite high altitude, 4370ft and it is hot in Kalahari desert, summers around 30 - 40 Celsius. But we also have an RV9A with a lycoming IO 320, not getting hot and barely using oil? What can cause the Mooney to use oil and run fairly hot? I have to trail the cowls to keep the temperature at about 217. I would appreciate any advice or help if someone had the same trouble with their M20J? Thanks Andries 

[PTK]

I'm not an expert on the subject but I can offer this piece of information to all the experts out there. I change oil and filter q 25 hours or 4 months religiously, utilizing 7 quarts of 15W50 Aeroshell at each oil change year round. When it starts approaching the 6 qt mark on the dipstick, which is typically at 20-22 hours, and it's hot weather and I plan to fly before the next oil change, I'll add a quart knowing that I'll be at 7+ quarts. So it runs just under a quart every 20 hours or so. I cruise at 2450 RPM because my prop is dynamically balanced there. WOT always except on approach and landing. Oil temp ranges from 160 to 180 depending.

Yes, I know and I've been told that I'm throwing away good oil. I consider it cheap insurance. I do clean the belly and gear door from residue here and there. The breather tube is there to spit oil. We need to accept the fact that air cooled engines will consume oil. So I've been told.

[PTK]

Quote: Andries

I 've been reading several posts on oil consumption. I am quite fed up with my M20J, 1980 model. It was running hot, so I had it checked at an AMO, kept it for 2 weeks and 50 000 later it was "fixed"... Replaced the verna therm, changed timing on magnetos, changed the oil pressure etc etc. 100 hours later, I was still not happy. Next AMO said cylinders was cracked. Replaced all 4, another 70 000. Flew it for 15 hours to seet cylinders, balls to the wall low level, still using excessive oil. Every 2 hours more than a bottle, 1litre! Took it back, they opened it, cam was full of "pitts", whatever that means. Another 6 weeks, new cam, gears etc etc, another 85 000! To put it together at the AMO, another 25 000. So now we are at balls to the walls again, it is now 17 hours, I fill it to 6, fly 2 hours, it is on 4. This happens every 2 hours. When is the oil supposed to settle? We are at quite high altitude, 4370ft and it is hot in Kalahari desert, summers around 30 - 40 Celsius. But we also have an RV9A with a lycoming IO 320, not getting hot and barely using oil? What can cause the Mooney to use oil and run fairly hot? I have to trail the cowls to keep the temperature at about 217. I would appreciate any advice or help if someone had the same trouble with their M20J? Thanks Andries 

[Shadrach]

Quote: GeorgePerry

  However - I would NEVER run a 200 HP IO-360 engine with less than 6 quarts of oil.   Flying with only 4 quarts is asking for trouble.

[wrench]

 

I recently had engine mounts replaced and during the replacement I inspected for the same issue. The cylinder head oil return line hoses were very hard to inspect with the engine exhaust still mounted so it was removed making access much easier for everything all around. This plane has engine preheat wiring also making any visual inspection very difficult and cylinder head return line hose replacement a real challenge if the exhaust system wasn't removed. (Just my observation).

I found three different brands of cylinder head return line hoses installed one which had a Mil-Standard marking but was hard as a rock and one marked “Jiffy hose” (automotive fuel line as I recall from those days) then two with no markings at all. The correct hoses were ordered for replacement.

Two of the eight worm drive hose clamps were stripped (no clamp load). All new clamps were installed. I found one cylinder head return tube (aluminum) abraded 1/2 way through the tubing by the inner baffle spring due to interference of the tension wire just to the outside of cylinder head return line hose. This was not a leak point yet but could have been in the future (Inspect for this interference every annual in my opinion).

The valve cover gaskets were all replaced. One of four was overtightened in past and gasket split causing a probable leak path.

None of these individual finds was a major problem in my opinion but all added up could easily be the aesthetic mess on the cowl and gear doors I seemed to have after every flight. It doesn't take many oil drips to make things look bad.

Results so far after three flight the lower cowling and gear doors are less and less oil stained so I believe the major oil seepage has stopped. This last 1.1 hour flight I didn't need to wipe it down.

One more note, these findings I'm told by AP's are typical for Lycomings and not Mooney specific.

Happy New Year all.

[jlunseth]

Be careful how you measure "oil loss.". If the plane has been sitting for a day or more and you start a flight with 5 qts., get out of the plane vwhen you land,pull the dipstick and see 4, there has been no oil loss.  The 1 qt. difference is oil that is now spread throughout the engine.  If you let it sit for a couple of days it will be back to 5 because the oil has now drained back into the crankcase, well, most if it.  Sounds like that is past of what is going on.

[OR75]

over time, I identified the following source of oil leaks (oil on the gear door and belly)

- Cylinder head oil return lines 4 rubber hoses (as described by flyingwrench above)

- Oil seeping inside front belly pannel during oil change as oil drips as I remove the filter

- Oil leaking from AN fitting / vent located at bottom of the engine in the exhaust shroud recess

- Rocker cover panels