Breather tube

[Shadrach]

Greetings all,

Where would be the best place to procure breather tube similar to the OEM part?  This is for a 1967 F model. Mine is so brittle that it's become challenging to R&R.  It likely started life as transparent, yellowish brown plastic. Years of service have turned it dark brown.

[Yetti]

It looks really close to the vinyl tubing you can get at home Dan.  The thicker stuff with braid in it could work.  Not sure what your IA would say

[Culver LFA]

My 67 F has a black rubber breather hose, it’s supposed to be transparent?

[Andy95W]

I used this:

https://www.aircraftspruce.com/catalog/appages/aq306.php

[Shadrach]

7 minutes ago, Andy95W said:

I used this:

https://www.aircraftspruce.com/catalog/appages/aq306.php

Many thanks! I’m pretty sure my ID is .75”. I’ll double check.

[Shadrach]

31 minutes ago, Culver LFA said:

My 67 F has a black rubber breather hose, it’s supposed to be transparent?

I bet yours has been changed. Mine has been in my family since early 68. I know my hose is OEM. I know it’s a common breather hose material for that time period because my 1973 Triumph T100R (motorcycle) is parked next to the Mooney and it has a breather that runs down the left side along the rear fender. It’s made from the same material and has turned the same color and is just as brittle.

[PT20J]

Same stuff was on my '78 J and again on my '94 J. Pretty sure it's just clear vinyl tubing yellowed by oil and time. When we had to remove it, we used a heat gun and it softened just like vinyl. Whenever I've needed to know what material Mooney used for a particular part, I've had good luck emailing the part number to technicalsupport@mooney.com and asking. If that doesn't work, call LASAR or Maxwell -- they have access to the Mooney Parts Portal.

[RobertGary1]

Odd mine is steal. 

 

-Robert 

[Shadrach]

11 hours ago, RobertGary1 said:

Odd mine is steal. 

 

-Robert 

You’ve a 3’ steel tube that goes from the top of the accessory case all the way down to the left cowl flap?

Edited January 3, 2019 by Shadrach

[Guest]

You could use Mil H 6000-12(3/4”) hose.

Clarence

[Andy95W]

2 hours ago, M20Doc said:

You could use Mil H 6000-12(3/4”) hose.

Clarence

Oops- sorry Ross- I must've meant that one-

https://www.aircraftspruce.com/catalog/appages/mil6000.php

[ArtVandelay]

You’ve a 3’ steal tube that goes from the top of the accessory case all the way down to the left cowl flap?

I think he means this part:



Tom

[Shadrach]

12 minutes ago, ArtVandelay said:

I think he means this part:



Tom

Perhaps, but I’m pretty sure Robert knows aluminum from steel and that piece is most certainly aluminum.

[EricJ]

I replaced mine a while back with Mil-6000 and took the time to cut a bird's mouth in it.   It spews a little inside the cowling, so now I'm thinking of replacing it and not cutting the bird's mouth, but I'm a little hesitant.   I'm guessing most installations don't have it?

[Shadrach]

1 hour ago, EricJ said:

I replaced mine a while back with Mil-6000 and took the time to cut a bird's mouth in it.   It spews a little inside the cowling, so now I'm thinking of replacing it and not cutting the bird's mouth, but I'm a little hesitant.   I'm guessing most installations don't have it?

I know what a birdsmouth joint is but I am not following the how and why regarding your breather.

[EricJ]

12 minutes ago, Shadrach said:

I know what a birdsmouth joint is but I am not following the how and why regarding your breather.

Ice hole.

aka whistle slot.

The result of an AD for Cessnas and Mooneys with bladders, and accepted practice for many airplanes these days.   The aluminum breather end on my airplane has no hole, so I cut one in the hose as per the AD (even though I don't have bladders).   It's making a small mess inside the cowl, but I'm a little reluctant to delete the hole.

Mooney AD:
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/6ff2eeba54075bb686256f65005b79bc/%24FILE/042504.pdf

Cessna AD:
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/AOCADSearch/89D2E182A363570F862569B9004D3EDE?OpenDocument

[Shadrach]

2 minutes ago, EricJ said:

Ice hole.

aka whistle slot.

The result of an AD for Cessnas and Mooneys with bladders, and accepted practice for many airplanes these days.   The aluminum breather end on my airplane has no hole, so I cut one in the hose as per the AD (even though I don't have bladders).   It's making a small mess inside the cowl, but I'm a little reluctant to delete the hole.

Mooney AD:
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/6ff2eeba54075bb686256f65005b79bc/%24FILE/042504.pdf

Cessna AD:
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/AOCADSearch/89D2E182A363570F862569B9004D3EDE?OpenDocument

Ok,  The first thing that popped in my head when I read that was Roman Maronie from Johnny Dangerously.

The second thing was, what an earth do bladders have to do with the crank case breather tube, And why would the FAA Limit the AD to bladdered birds only. There is no fargin ice hole in my breather tube and it’s never had a problem doing it’s job. That being said, my engine has never pushed a lot of oil through the breather.  Mostly vapor, it almost never drips. 

[Bryan]

My M20K, TSIO-360-SB (1998) has the Whistle Hole close the aluminum & rubber joint that appears to be from the factory since nothing written about it in my logs.  But K's are not listed (as I read) in this AD maybe because of this inclusion from original parts.

[Andy95W]

Mine has a hole in the aluminum tube, just inside the cowling, above the cowl flap.

[carusoam]

When selecting a replacement hose...

Something on the line of an oil hose would be best...

• Temperature wise... it may get hot...
• Chemical wise... it is designed to handle the oil...
• cost is in line

The PVC tube that was being considered, or was used before... is called plasticized PVC.  The plasticizer leaves the material over time, it browns and gets brittle....  Also isn’t very temperature resistant like the oil hose rubber.

where the fargin’ ice hole belongs...?  (Thank you Roman Maronie)

• Closer to the warm engine is better than closer to the freezing environment...
• The rubber hose acts as a thermal insulator, the chance of ice forming there is pretty low...
• The aluminum tube acts as a conductor and it’s exposed to the outside air, but, a better place for drilling a hole...
• Since a quart of oil seems to come down the hose every now and then... the lower the better...

The concern would be... if enough vapor collects in the tube, then it freezes, where does the pressure leave the case?

expect that stuff is going to get pressed out somewhere... likely at the most loose seal like the prop shaft.

Gives us a reason to check the drains leaving the engine bay... use caution, one hose may have battery acid in it... the battery box has a drain too.  

PP thoughts only, not a mechanic...

Best regards,

-a-

[N811SS]

Greetings All -

Looking for a little advice.  My 1967 M20F (with 201 conversion kit) consumes about 1 qrt of oil every 3.5 hours.  The oil gets darker than it should after about 6-8 hours of operation so I know I have ring blow-by issue.  I took it to Gibbs (at KMYF) and had them check the crank case pressure with my most recent oil change.  Indeed, the pressure was higher than it should be.  I have already honed these cylinders twice before (which was after the Ameritech engine rebuild 700 hours ago...which is a very long/depressing/expensive story) so I am not really interested in doing yet another top overhaul.    The curious thing was that the mechanic said that there was quite a bit of vacuum pressure happening at the breather tube exit point even with just the plane on the ground and the engine rev'd up.   I used to have an airwolfe air/oil separator but took it off awhile back (the oil consumption did not go up or down with its removal) but the metal tube (which has the hole in it for icing protection) is flat, meaning horizontal, and flush with the firewall.   I see in these pictures that your breather tube has a 90 deg bend and sweeps aft.  Here is my question --> If I change my tubes exit configuration to sweep back towards the tail will that reduce the venture effect and perhaps help draw less oil out the breather tube?   

 

[N201MKTurbo]

54 minutes ago, N811SS said:

Greetings All -

Looking for a little advice.  My 1967 M20F (with 201 conversion kit) consumes about 1 qrt of oil every 3.5 hours.  The oil gets darker than it should after about 6-8 hours of operation so I know I have ring blow-by issue.  I took it to Gibbs (at KMYF) and had them check the crank case pressure with my most recent oil change.  Indeed, the pressure was higher than it should be.  I have already honed these cylinders twice before (which was after the Ameritech engine rebuild 700 hours ago...which is a very long/depressing/expensive story) so I am not really interested in doing yet another top overhaul.    The curious thing was that the mechanic said that there was quite a bit of vacuum pressure happening at the breather tube exit point even with just the plane on the ground and the engine rev'd up.   I used to have an airwolfe air/oil separator but took it off awhile back (the oil consumption did not go up or down with its removal) but the metal tube (which has the hole in it for icing protection) is flat, meaning horizontal, and flush with the firewall.   I see in these pictures that your breather tube has a 90 deg bend and sweeps aft.  Here is my question --> If I change my tubes exit configuration to sweep back towards the tail will that reduce the venture effect and perhaps help draw less oil out the breather tube?   

 

I doubt that it would have much affect.

There is more to ring sealing than the cylinder walls. The rings also seat on the ring lands. I have seen worn out pistons and overheated pistons that had poor sealing on the ring lands. The only way to fix it is to replace the piston. 

The up side is over time deposits will build up in lands and improve the sealing...

Have you identified the cylinder(s) that are causing the problem?

[PT20J]

The purpose of the crankcase vent is to prevent pressure buildup in the crankcase. It's curious that there is a significant vacuum at the breather on the ground since that would indicate that pressure is lower that atmospheric in the crankcase. If you are using oil, the first thing is to figure out where it's going. If the belly isn't really oily, it's not coming out the breather, it's getting burned. I once had a broken oil control ring that caused the engine to burn 1/2 qt per hour and the belly was clean. I once had a Lycoming that got 4.5 hours per quart -- most of it was getting burned, but it had some minor leaks that made a BIG mess on the belly. It doesn't take much oil in the slipstream to make a mess.

If you are using a single viscosity oil, you might try switching to 20W-50 and see what happens. Many report lower oil consumption if the oil is getting past the rings and being burned. 

Skip

[carusoam]

See if we can summarize things...

1) Something may be getting lost in the description...

2) Oil is leaving the system at a higher rate than normal...

3) engine hours and cylinder hours would be important base line info...

4) pics with a dental camera can tell a lot about cylinder wear... cross hatch or no... rust pits or no...

5) Compression info might be helpful....

6) excess oil likes to escape out the breather tube (the one with the hole...

7) oil getting past the rings is going to show up somewhere... plugs, exhaust pipe...

8) oil escaping the breather drips off the tail tie-down...

9) dark oil, foamy oil, and exhaust smell are indications of exhaust passing rings...

10) case pressure is often measured with an ASI.

11) twice honed cylinders... should be in good shape, still want to check if something has gone wrong...

12) What is vacuum pressure that is being measured at the breather line..?

13)By all descriptions... you have blow-by... exhaust pressure leaving the cylinder, into the oil pan, possibly foaming the oil, followed by the oil escaping out the case vent...

14) Is it one cylinder, or all four..?

It may be a simple chase the oil leak... to find a broken ring...

PP summary of things I think I read here...

Best regards,

-a-

[N811SS]

All good questions/responses.   Thanks.  To provide some more details:

Engine Background:

* Engine is an IO360-A1A (the original)
* Engine rebuild was 700 hours (about 7 years) ago.  Re-honed cylinder 2 & 4 at the 125 hour mark.  Replaced cylinder 3 at the 400 hour mark due to broken ring.  Re-honed cylinder 3 at the 500 hour mark again.  Through-out all of this, oil consumption has remained at 1 qtr every 3.5 hours.

* The oil gets dark (but not real bad) by 8 to 10 hours after a change....and that's considering that I keep adding a qrt each 3 to 4 hours.

* The belly on the left side (behind the breather tube) gets a little bit oily but nothing too bad.

* The engine compartment is perfectly clean (no oil drips anywhere).  Nor have I ever seen oil drips on the ground after parking. 

* Have done borescope many times and there is usually a little bit of oil on the bottom of cylinder 3 but nothing too bad according to the mechanic.  The hatching on the walls looks good to everyone and no signs of glazing.  The compression's are good in all 4 cylinders (76/78/78/77).  The bottom plug on cylinder 3 has a little bit of oil in it but I cant say the plug has every been fouled.  

* Its just weird, I keep feeding oil into this thing and it just disappears...I guess it is getting past the rings and burned in the exhaust...its quite the mystery.

 Crankcase Pressure (according to the mechanic):

 The only reason that the wind from the prop blowing past the exit port of the breather tube might be creating a negative pressure in the crankcase is because the mechanic hooked-up a manometer water tube to the dipstick filler.  He tried 1000, 1700, 2500 rpms and could not get a positive pressure in the crankcase!  He could hear the engine puffing past the rings but at full rpms the crankcase pressure was negative (3" of water in his tube)!  The top cowling was off but the bottom cowling was on.  I asked if he compared open cowl flap to closed cowl flap and he said no.  Then, he disconnected the black crankcase breather hose up near the accessory case and voila all of the sudden he could measure positive crankcase pressure at double the normal range.  He surmised that prop wash was creating a venturi effect on the breather tube.  I know that sounds like a stretch especially considering that tube is angle-cut such that the opening is facing backwards (see photo below) but I noticed that other Mooneys have the breather tube run toward the tail for about 5" .

 

...So here is what I did this afternoon.  I went and bought a small section of tubing from the auto-parts store with a 90 deg bend and clamped it on the existing (see below).  I am doubtful it is going to make a difference but I don't see the harm in giving it a try.  I will report back my findings. 

Here is just a Mooney photo i picked off the internet (its not my plane) showing the breather hose pointed aft: