Did my dog puke by my front tire??

[ottorecker]

About a month ago my airport neighbor was grabbing the tug from my hangar and noticed what he called 'dog puke'  by my front tire.    Sure enough, when I got to the hangar there was a nice deposit right underneath the breather tube.  What I normally see at that spot is just a a spot or two of dark colored oil and not this color and amount of fluid out of our M20K.  When my hangar neighbor noticed this it was after a 6 hour nonstop flight.  This event was apparently not a one-off.  The pic below was after a 3+ hour flight and very similar to the first occurrence.  I'm not yet sure if this is a trend but it's starting to look like it.  Are coyotes creating hangar mischief?  Aliens perhaps?  Most importantly, is this something I need to be worried about?  Oil is Phillip's xc20w-50 with Camguard.

 

[Aerodon]

that looks like the sludge that comes out of the oil breather  tube?

[PT20J]

Water mixed with oil? Is there any moisture on the dipstick?

[GeeBee]

Yep that is oil with moisture. Not unusual out the breather. It is why they call jars that capture breather contents “puke jars”

If you have it anwhere else in the engine then it is a problem.

[EricJ]

+1 that it's moisture and oil.   If the oil on the dipstick looks okay it's probably not an issue.

[ottorecker]

No water on the dipstick so far.  Thanks all for the input.

[MB65E]

Multi grade oil and water…

aeroshell 15/50 will do it too.

I have not seen straight weight oils do it.

-Matt

[PT20J]

Fuel oil and water will do it. Parent’s house had an oil furnace and the underground tank leaked and water got in. It’ an emulsion of oil and water.

[Bartman]

I may be wrong but isn’t that unusual to see after a 3 hour flight?  Back when I drove 2 miles to work I would see that on the dipstick and I considered that normal for the circumstances. It resolved after I drove longer distances. 
 

Since this is seen after a 3 hour flight I would expect the oil to be at operating temperature and boil off the moisture. Is there something wrong with the oil cooler bypass valve?  Stuck and the oil is constantly circulating and running too cool?

Do you have oil temp on an engine monitor ?

[ottorecker]

All engine temp indications where in the normal range.  I was just a little puzzled that I've not seen this type of fluid out of the breather until recently.  It's about time to change the oil anyway so I might try that to see if that makes a difference.  Sounds like it would probably help if I flew the aircraft more often.....alas, life has recently got in way...unfortunately.

[Pete M]

Not an a&p but I'd consider flushing the sump with some manner of caustic sludge dissolving concoction that wont harm aluminum and filling with a straight weight and camguard. Big temp changes around the country, condensation and such. Seems like it might take a bit of combustion blow bye to create that. (Sulfur?) so i wonder how the piston rings are holding up. I wouldnt do anything radical, just fly the heck out of it, you know, cause that fixes everything:)

Pete

[GeeBee]

Moisture is a by-product of combustion. The air leaving the crankcase is very moist. When it enters the breather tube is condenses because the breather tube is cool. After three hours the oil in the crankcase will be moisture free, but you cannot avoid moisture from combustion blow by. Which is why you want a feed of dry air after shut down to carry it all away.

 

 

[Shadrach]

Some good information in this thread and some not so good information in this thread. To start with the bad... don’t put any additives in your oil to “clean the sump”. The sump is likely just fine as is the oil inside. As others have stated, what you are seeing is a mixture of oil and water from the breather. I can only speculate as to why it’s happening but I suspect it may have to do with the OAT during your flights. Believe it or not, moisture can freeze inside the breather tube. That oil saturated moisture starts to melt back at the hangar leaving what looks like funky peanut butter on the floor.  The Coldest ( 5°F) night I’ve ever spent outside was in the Pecos, so I know that Santa Fe gets colder than most folks think.

Edited February 14, 2022 by Shadrach

[Pete M]

4 hours ago, Shadrach said:

Some good information in this thread and some not so good information in this thread. To start with the bad... don’t put any additives in your oil to “clean the sump”. The sump is likely just fine as is the oil inside. As others have stated, what you are seeing is a mixture of oil and water from the breather. I can only speculate as to why it’s happening but I suspect it may have to do with the OAT during your flights. Believe it or not, moisture can freeze inside the breather tube. That oil saturated moisture starts to melt back at the hangar leaving what looks like funky peanut butter on the floor.  The Coldest ( 5°F) night I’ve ever spent outside was in the Pecos, so I know that Santa Fe gets colder than most folks think.

I did not say to add it to the oil, i said "to flush the sump". I agree, to add it to your oil would be stupid. Am I to understand you're saying sludge doesnt collect at the bottom of the sump? If it does collect there, can we assume it contains combustion byproducts and possibly some water? Can we further assume that not every drop of it comes out when you open the drain? Will flushing it with an approved substance hurt anything? I fly many different little airplanes all day long, every day, and have for years. I had my mooney for 8 years based in extreme heat and cold, and I've never seen a sample that bad, though I've seen some with yellow specks. Like I said, given the turbo charging and lack of use, maybe more combustion is getting past the rings than is ideal, but I dont know. I'd want to clean everything out the best i could, fresh oil, fly, re-evaluate. I think your frozen breather theory may be correct, but its the vibrant color and density that gets my attention. Its too dense.

[Shadrach]

8 hours ago, Pete M said:

I did not say to add it to the oil, i said "to flush the sump". I agree, to add it to your oil would be stupid. Am I to understand you're saying sludge doesnt collect at the bottom of the sump? If it does collect there, can we assume it contains combustion byproducts and possibly some water? Can we further assume that not every drop of it comes out when you open the drain? Will flushing it with an approved substance hurt anything? I fly many different little airplanes all day long, every day, and have for years. I had my mooney for 8 years based in extreme heat and cold, and I've never seen a sample that bad, though I've seen some with yellow specks. Like I said, given the turbo charging and lack of use, maybe more combustion is getting past the rings than is ideal, but I dont know. I'd want to clean everything out the best i could, fresh oil, fly, re-evaluate. I think your frozen breather theory may be correct, but its the vibrant color and density that gets my attention. Its too dense.

My apologies Pete for misreading your recommendation.  

That is not an oil sample.  That is a mix of condensed water vapor and oil that collected in the breather tube and then plopped onto the floor.  Just to be clear, the crankcase vent is on top of the engine. The vapor from the vent is channeled through a tube back to the bottom of the cowl. Anyone that has ever run an engine with a catch cam knows that what’s in the can is not a great proxy for the condition of the engine oil. Catch cans are often nasty. The fact that his dipstick looks normal suggests that the “peanut butter” dollop on he floor has more to do with what is happening in the breather than what is happening in the sump.

Edited February 15, 2022 by Shadrach

[carusoam]

Good news and some not good news…

1) Your dog is probably healthy…

2) you have a few oil drops landing in the same place, showing a bit of history on the floor…

3) Other M20K pilots haven’t mentioned this before…

4) So… probably is moisture and oil mixing together…

5) But that is a lot to come out after a flight…

6) Is the belly clean? (Proof that is only after the flight)

7) No foamy oil in the case after the flight (proof that the rings are still working as expected, leaky ones make great foam producers)

8) Let’s see if @M20Doc has seen this behavior before… (moisture and oil mixture seemingly escaping the case vent line)

Good luck with the hunt!

PP thoughts only, not a mechanic…

-a-

[A64Pilot]

It’s normal

The reason why your seeing it now is cold temps, it’s cold enough so that the breather tube never gets warm enough to not condense the vapor in the blow-by.

There is always vapor in blow by, so long as your burning fuel your making water and this water is vapor and is carried out via the tube.

I’ve never understood why aircraft blow by tubes are metal. if they were insulated then they couldn’t freeze, no need for a whistle slot, but as they are metal in cold weather  they can freeze shut.

If I ever build an Experimental airplane I’ll connect the breather tube to the exhaust and make it a Venturi for a slight negative pressure, it couldn’t freeze and ought to eliminate the greasy belly too.

Edited February 15, 2022 by A64Pilot

[Browncbr1]

start opening the oil filler cap to let the steam out after shutting down from now on and you won't get much if any water in your oil

Edited February 16, 2022 by Browncbr1

[A64Pilot]

You really under normal circumstances should never get any water in the oil, yes water is a by product of burning fuel, but with oil temp above 165 (actual high oil temp is much higher than where we measure it) the moisture can’t accumulate in the oil, it’s cooked off immediately, sort of like frying chicken never gets water in the oil, but water flashing off to steam is why the oil boils up. Of course we don’t dump a big load of water like frying chicken, it’s a small bit of moisture continuously.

Ever seen water drip from a cold cars exhaust? same deal, when the exhaust heats up, the water is gone. What’s going on here is that the tube due to cold weather never gets hot enough, so the water continues, and forms an emulsion with the oil, water and oil don’t mix under normal temps, but get them hot enough and they do.

Edited February 17, 2022 by A64Pilot