Excess oil coming out of vent tube

[warrenehc]

Hello,

I have had my Mooney F for about 20 months and put 280 hours on it.

Engine has about 1250 smoh.

I just replaced the fuel servo and over the last 20 hours my oil consumption has went up.

I normally had ran it on long trips 3-4 hours starting with 6.5qts. after stopping overnight I will have one or two drips from the vent tube and nothing under the belly.

Since the fuel servo replacement I have noticed many more drips 10 or so on the floor after stopping and the area going back from the vent tube is showing signs of oil and dirt. 

firewall and other engine areas are clean.

I am using more oil 3/4ish more oil per 10 hours. 
 

I have bumped it down to 6 qts. per 2 hour trip and still seeing the same thing.

Can anyone provide any insight on how this could be right after the fuel servo replacement.

Any tips to change this?

Edited October 17, 2022 by warrenehc

[carusoam]

Good news…

Oil use is usually not directly related to the fuel servo….

 

But…. Did you do any high powered break-in type flights?

Any dozens of trips around the pattern, T/Os and landings?

Any Vx T/Os?

 

Has the OilT been really warm lately?

Is the oil getting darker faster than usual?

Does the oil have an exhaust aroma?

Any bubbles or foaming in the oil seen after the flight?

Things that come to mind…

 

PP thoughts only, not a mechanic…

Best regards,

-a-

[David Lloyd]

There are two drains from the mechanical fuel pump, one that will vent fuel if the upper diaphragm leaks, the other for oil if the lower diaphragm leaks. Check to make certain the oil is coming from the breather vent and not the fuel pump drain.

[warrenehc]

8 hours ago, carusoam said:

Good news…

Oil use is usually not directly related to the fuel servo….

 

But…. Did you do any high powered break-in type flights?

Any dozens of trips around the pattern, T/Os and landings?

Any Vx T/Os?

 

Has the OilT been really warm lately?

Is the oil getting darker faster than usual?

Does the oil have an exhaust aroma?

Any bubbles or foaming in the oil seen after the flight?

Things that come to mind…

 

PP thoughts only, not a mechanic…

Best regards,

-a-

No to everything basically.

All trips are XC.

oil temps got to 225 once or twice due to high outside temps.

[warrenehc]

4 hours ago, David Lloyd said:

There are two drains from the mechanical fuel pump, one that will vent fuel if the upper diaphragm leaks, the other for oil if the lower diaphragm leaks. Check to make certain the oil is coming from the breather vent and not the fuel pump drain.

Will have to quadruple check but all oil is coming from vent line.

[Ragsf15e]

5 hours ago, David Lloyd said:

There are two drains from the mechanical fuel pump, one that will vent fuel if the upper diaphragm leaks, the other for oil if the lower diaphragm leaks. Check to make certain the oil is coming from the breather vent and not the fuel pump drain.

I’m in 90% agreement, but I think there’s only 1 actual drain from the mechanical fuel pump.  You’re right that it will leak either fluid depending on which diaphragm is leaking.  The other drain tube commonly attached to or next to that as it exits the cowl is the sniffle valve drain which will occasionally leak a few drips of fuel after shutdown.

I definitely agree that he should make sure it’s coming from the breather and not the fuel pump drain as it can be hard to tell since they are close to each other.

common things that make oil come out the breather… over fill oil (sounds like you knew and didn’t do this), blowby from a leaking cylinder (bad rings, crosshatching worn, etc)which pressurizes your case and pushes out oily air.  Compression may still be good due to oil sealing the worn cylinder at the pressure of the air test but not during combustion.  Are any cylinders oily?

What type of cylinders?  Chrome are known for this, but not many have chrome anymore…

[warrenehc]

1 hour ago, Ragsf15e said:

I’m in 90% agreement, but I think there’s only 1 actual drain from the mechanical fuel pump.  You’re right that it will leak either fluid depending on which diaphragm is leaking.  The other drain tube commonly attached to or next to that as it exits the cowl is the sniffle valve drain which will occasionally leak a few drips of fuel after shutdown.

I definitely agree that he should make sure it’s coming from the breather and not the fuel pump drain as it can be hard to tell since they are close to each other.

common things that make oil come out the breather… over fill oil (sounds like you knew and didn’t do this), blowby from a leaking cylinder (bad rings, crosshatching worn, etc)which pressurizes your case and pushes out oily air.  Compression may still be good due to oil sealing the worn cylinder at the pressure of the air test but not during combustion.  Are any cylinders oily?

What type of cylinders?  Chrome are known for this, but not many have chrome anymore…

Yes definitely from the vent tube.

Do not believe they are chrome. 
 

exterior of all cylinders are clean.

[David Lloyd]

2 hours ago, Ragsf15e said:

I’m in 90% agreement, but I think there’s only 1 actual drain from the mechanical fuel pump.  You’re right that it will leak either fluid depending on which diaphragm is leaking.  The other drain tube commonly attached to or next to that as it exits the cowl is the sniffle valve drain which will occasionally leak a few drips of fuel after shutdown.

I definitely agree that he should make sure it’s coming from the breather and not the fuel pump drain as it can be hard to tell since they are close to each other.

common things that make oil come out the breather… over fill oil (sounds like you knew and didn’t do this), blowby from a leaking cylinder (bad rings, crosshatching worn, etc)which pressurizes your case and pushes out oily air.  Compression may still be good due to oil sealing the worn cylinder at the pressure of the air test but not during combustion.  Are any cylinders oily?

What type of cylinders?  Chrome are known for this, but not many have chrome anymore…

You’re absolutely correct, one drain from between the diaphragms.  

[Ragsf15e]

1 hour ago, warrenehc said:

Yes definitely from the vent tube.

Do not believe they are chrome. 
 

exterior of all cylinders are clean.

If they were chrome, there should be an orange stripe painted on them.  Usually the cooling fins.

By oily cylinders, I mean inside.  You need to get a borescope in there and look for oil pooling and or missing/scraped crosshatch.  Probably do a compression check while you’re there as that would identify an issue with a stuck ring or something similar.

[warrenehc]

Cylinders are not chrome.

 

[WAFI]

Does anyone know if there is a procedure to do a "leak down test" on the cylinders to check the amount of blow by?

In my opinion this is a better way to check the integrity for the piston rings and cylinder walls.

@M20Doc

[EricJ]

2 hours ago, WAFI said:

Does anyone know if there is a procedure to do a "leak down test" on the cylinders to check the amount of blow by?

In my opinion this is a better way to check the integrity for the piston rings and cylinder walls.

@M20Doc

That's the standard "compression test" that is done on these engines and should be done every annual.    You can take the oil fill cap or dipstick out and listen during the leakdown/compression test to get an idea if there's a lot of blowby.

[EricJ]

3 hours ago, warrenehc said:

Cylinders are not chrome.

I doubt that the servo work and this issue are related unless something got bumped/disturbed during the installation.   Nothing in the servo should affect the amount of oil going out the vent.

 

[Guest]

3 hours ago, WAFI said:

Does anyone know if there is a procedure to do a "leak down test" on the cylinders to check the amount of blow by?

In my opinion this is a better way to check the integrity for the piston rings and cylinder walls.

@M20Doc

A standard aviation compression check does this, allowing you to determine if there is a leak from the valves, rings or a cracked cylinder head.  S/I 1191A for Lycoming and S/B03-3 for Continental.

[Fly Boomer]

1 hour ago, M20Doc said:

A standard aviation compression check does this, allowing you to determine if there is a leak from the valves, rings or a cracked cylinder head.  S/I 1191A for Lycoming and S/B03-3 for Continental.

And, as Clarence pointed out before, the compression check tools are different.

[EricJ]

8 minutes ago, Fly Boomer said:

And, as Clarence pointed out before, the compression check tools are different.

You can use the same tools for each.    Both the Lycoming SI and Continental SB specify testers with an 0.040 orifice, which is the critical spec for the tester.   

[Guest]

3 hours ago, Fly Boomer said:

And, as Clarence pointed out before, the compression check tools are different.

The tools are the same, the acceptable low is different.  Lycoming uses a standard value, where Continental uses a master orifice to calculate the acceptable low limit for that day.  The master orifice tool can be attached to the tool or added to the spark plug adapter.  

[A64Pilot]

If your going to buy one, buy this one. it has the master orifice built in and is therefore good for both Lycoming and Continental engines.

https://www.aircraftspruce.com/catalog/topages/diffcylindere2m1000.php?clickkey=31031

You can supposedly buy the orifice by itself to use with a tester that doesn’t have one, but I’ve never seen one, I bet they aren’t common.

 They come  in two flavors, one for big motors like big Radials that has a .060 orifice. This one is for flat motors like we all have and has a .040 orifice. The big motors can leak more and still be good because the cylinders are so much bigger, so they have a larger orifice.

‘The one I linked to says it has the .060 orifice, I think that’s incorrect, but check, you want the .040

[carusoam]

Pics from inside the cylinder are next on the list…

Valves that look like pizzas are good… tulips are bad…

Surfaces of the cylinder have good hatch patterns, not shiny, smoothed, or flaky, cracked surface areas…

PP thoughts only, not a mechanic…

Best regards,

-a-

[Will.iam]

How soon does your oil turn black after an oil change will give you an idea how bad the blowby is. A new engine can go for 20 hours plus and still be yellow in color some even get to the next oil change with little color change. My oil turns black in less than 5 hours and my cylinders have no crosshatch left at TBO. 

[Fly Boomer]

13 hours ago, M20Doc said:

The tools are the same, the acceptable low is different.  Lycoming uses a standard value, where Continental uses a master orifice to calculate the acceptable low limit for that day.  The master orifice tool can be attached to the tool or added to the spark plug adapter.  

Apologies.  I could have sworn that you posted pictures of the two types previously.

[Guest]

10 hours ago, Fly Boomer said:

Apologies.  I could have sworn that you posted pictures of the two types previously.

I can if it helps.

[Fly Boomer]

4 minutes ago, M20Doc said:

I can if it helps.

Nah.  I was trying to be helpful, but working with incomplete knowledge.  Thanks for all you do.