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Breather DWG OP-27

wirejock

Well Known Member
Has anyone found a hose that fits better?
See photo.
Vans provides a hose EA-CV-HOSE-9816, but it's way bigger than the breather fitting. It does fit the tube FF-705, but the flare could be removed and the tubing diameter would match the breather.
Planning on a visit to the auto parts to search.

I also didn't install the nutplate for the adel clamp. No idea how I'm going to get that done!
20221220_152458.jpg
 
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For whatever reason, Van's assumes your engine has a Lycoming 71140 breather installed (3/4" hose) and provides that NAPA Heater hose with 90° elbow 3/4" to adapt to the flared end of the FF-705.

The B1E, M1B, etc. seem to have AN844-10D installed (45° 5/8" Tube-NPT).

I cut about 12" from the flared end of the FF-705. Then connected a length of 5/8"ID MIL-DTL-6000D hose from the AN844-10D to the remaining section of FF-705. Attached the FF-705 to the firewall with 2 MS219190-WDG10 (IIRC) clamps.
 
A "second" for the parts and method Brian describes. I removed my Lycoming installed 71140, and put in a AN844-10D, after the engine was hung on the mount (so, it can be done).

One plus is that by using the 45 degree elbow, you can point the elbow (thus the breather hose routing) in the right direction towards the FF-705. And, by using the MIL-6000 oil rated hose you won't have do ever deal with the supplied auto coolant hose getting soft and sticky...as it eventually will. My original section of MIL-6000 hose lasted about 10 years before it aged enough to leak at the FF-705 connection.

One warning so you won't be surprised, an aluminum AN844-10D will set you back about $45.....bigger AN fittings definitely more $$ than the 1/4 and 3/8" ones we normally use. Good news...only one required. :)
 
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MIL-DTL-6000D-10

For whatever reason, Van's assumes your engine has a Lycoming 71140 breather installed (3/4" hose) and provides that NAPA Heater hose with 90° elbow 3/4" to adapt to the flared end of the FF-705.

The B1E, M1B, etc. seem to have AN844-10D installed (45° 5/8" Tube-NPT).

I cut about 12" from the flared end of the FF-705. Then connected a length of 5/8"ID MIL-DTL-6000D hose from the AN844-10D to the remaining section of FF-705. Attached the FF-705 to the firewall with 2 MS219190-WDG10 (IIRC) clamps.

Now that makes sense. Mine has a 5/8" nipple. Probably the one you mention. Glad it's imstalled. That fitting is $125 on Spruce. Yeow!
Thanks. I will add it to my shopping list.
Looks likenI installed the nutplate too. Go figure.
Love it when a plan comes together. :D
 
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I simply cut the nice bend radius off the Vans supplied aluminum tube and connected ~12" of automotive engine breather tube from Napa between the Lycoming fitting (45 degree) and a lower straight section of tube to exit the cowl onto to the exhaust. I could not find a way to connect what Vans supplied and I figured purpose made engine breather tubing was better than the supplied heater hose.... my .02.

Breather line by Dave Hock, on Flickr
 
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Go to local parts store

I just called my local OReily's and said "I need a 5/8" hose with a 90 degree bend in it". They had one waiting on the counter by the time I got there. Trimmed the ends and it worked great.
 
Breather line

I simply cut the nice bend radius off the Vans supplied aluminum tube and connected ~12" of automotive engine breather tube from Napa between the Lycoming fitting (45 degree) and a lower straight section of tube to exit the cowl onto to the exhaust. I could not find a way to connect what Vans supplied and I figured purpose made engine breather tubing was better than the supplied heater hose.... my .02.

Is the breather supposed to exit below the cowl pointed down, forward, aft? Or is it supposed to dril on the exhaust pipe? Sounds wrong to me but I don't know what I don't know.
 
Is the breather supposed to exit below the cowl pointed down, forward, aft? Or is it supposed to dril on the exhaust pipe? Sounds wrong to me but I don't know what I don't know.

What I did Larry and working fine:

Engine breather by Dave Hock, on Flickr

Vans says to point it towards the exhaust pipe to burn off the oil mist... I did the best I could with the Vetterman exhaust pipes and hangars.
 
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Breather tube

New problem...
The plans show the aluminum breather tube installed so it's just above the exhaust pipe. The breather tube is prebent sonit will be several inches forward of the firewall and right above the exhaust pipe. No problem.

The problem is I have an engine dehydrator. The supply goes into the dipstick. The vacuum side plugs into the engine crankcase vent. No way I can get in there to plug it in with the cowl on and the pipe right above the exhaust.

Anyone else figure this out?
 
Is the breather supposed to exit below the cowl pointed down, forward, aft? Or is it supposed to dril on the exhaust pipe? Sounds wrong to me but I don't know what I don't know.

The breather exit should point at the exhaust pipe, about 1” away. The idea is that any crankcase vapors/oil-laden mist will get burned up by the hot exhaust and not end up on the belly.

Cut a few slots in the FF-705 (whiffle slots) about 2” or so above the exit also.
 

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The breather exit should point at the exhaust pipe, about 1” away. The idea is that any crankcase vapors/oil-laden mist will get burned up by the hot exhaust and not end up on the belly.

Cut a few slots in the FF-705 (whiffle slots) about 2” or so above the exit also.

What is the function of the "wiffle" slots?
 
What is the function of the "wiffle" slots?

So any potential blockage (ice for example) can't block the breather and blow out the main nose seal due to excessive crankcase pressure. Mine is a "whistle" slot versus "wiffle" :)
 
It's in the RV construction manuals:

i-PQWCsTn-M.jpg
 
Manual

It's in the RV construction manuals:

i-PQWCsTn-M.jpg

I went through the manual again yesterday to double check firewall forward. Never saw that. Thanks
I will re-re-read.
"Scotomisation" is the psychological tendency in people to see what they want to see and not see what they don't want to see.
 
I went through the manual again yesterday to double check firewall forward. Never saw that. Thanks
I will re-re-read.
"Scotomisation" is the psychological tendency in people to see what they want to see and not see what they don't want to see.

"Scotomization" ... had to look that one up to check. Thanks!
 
Larry, suggest putting the hole a bit higher. Local A&P suggested at least 6 or so inches up (he has seen some freezing down lower)(my hole is prob 12 inches up). Simply drill a hole and use the other end of the drill bit and put it in the hole and lift up to deform the metal locally.

Also, that tube that Van's sends will very quickly get that slimy oily look. Mine already has it. Glad you started this thread that has some ideas on how to address it.

Double also, definitely get that pipe above the exhaust if you can. Anything a guy can do to minimize the mess on the underside of the plane is best.
 
Mine's an 8 but almost the same. I have it exiting just above the exhaust, high enough so I can "easily" get the dehydrator hose on there with just a bit of fiddling.

http://www.rv8.ch/oil-breather-tube-installed/

img_9674.jpg

I've read the breather tube "icing" warning, but kind of struggle to understand what might cause this to happen - does anyone have some further details on what might cause the breather to clog due to ice?
 
Mine's an 8 but almost the same. I have it exiting just above the exhaust, high enough so I can "easily" get the dehydrator hose on there with just a bit of fiddling.

http://www.rv8.ch/oil-breather-tube-installed/

View attachment 35613

I've read the breather tube "icing" warning, but kind of struggle to understand what might cause this to happen - does anyone have some further details on what might cause the breather to clog due to ice?

Theoretically the air inside the cowl could be cold enough to ice the tip (moisture from engine). I don't know how feasible that is though as I have no idea what temp rise air usually sees going through the cylinders. I can confirm though that on a 172 I have built up frothy icy oil on the breather. Looked almost like thick boogers.
 
Breather vent hole

Larry, suggest putting the hole a bit higher. Local A&P suggested at least 6 or so inches up (he has seen some freezing down lower)(my hole is prob 12 inches up). Simply drill a hole and use the other end of the drill bit and put it in the hole and lift up to deform the metal locally.

Also, that tube that Van's sends will very quickly get that slimy oily look. Mine already has it. Glad you started this thread that has some ideas on how to address it.

Double also, definitely get that pipe above the exhaust if you can. Anything a guy can do to minimize the mess on the underside of the plane is best.

Jereme
What size hole did you drill?
Which way did you bend the hole with the bit? Up or down?
 
Freezing of the breather was a common problem in early single engine Cessna aircraft, so much so that the FAA issued an AD back in 1982. Copy below:


AIRWORTHINESS DIRECTIVES FINAL RULES: 82-07-02

CITATION: This information is not available.

PAGE NUMBER:

DOCKET NUMBER: Unknown

AMENDMENT: 39-4353

AD NUMBER: 82-07-02

SUBJECT HEADING:
Airworthiness Directives; Cessna Models 170A, 170B, 172, 172A through 172P, 175, 175A, 175B, 175C, P172D, and R172E (USAF T-41B) Airplanes

ACTION:

SUMMARY:

DATES: Effective April 8, 1982.

ADDRESSES:

FOR FURTHER INFORMATION CONTACT:

SUPPLEMENTARY INFORMATION:

REGULATORY TEXT:
82-07-02 CESSNA: Amendment 39-4353. Applies to Models 170A, 170B, 172, 172A through 172P, 175, 175A, 175B, 175C, P172D, and R172E (USAF T-41B) airplanes modified in accordance with STCs SA3-13, SA3-126, SA3-571, SA3-672, SA3-674, SA135CE, SA420CE, SA421CE, SA424CE, SA610SW, SA647CE, SA777CE, SA806CE, SA807CE, or SA1324CE, certificated in any category.

COMPLIANCE: Required as indicated, unless already accomplished.

To reduce the possibility of rapid loss of engine oil caused by ice obstruction of the engine crankcase breather, accomplish the following:

A) Within the next 50 hours time-in-service after the effective date of this AD:

1. Visually examine the engine crankcase breather to determine if an alternate air outlet is drilled or cut in the tube as shown in Figure 1. If any of these provisions exist, make an appropriate entry in the aircraft maintenance records per paragraph B). No further action is necessary.

2. If the hole or cutout shown in Figure 1 is not in the engine crankcase breather tube:

a. Inspect the crankcase to crankshaft seal and ensure that the seal is secure. (This seal is located behind the starter ring gear in the forward most part of the crankcase.) Reinstall or replace this seal if it is not flush with the forward face of the crankcase.

b. Drill the engine crankcase breather tube line to include an alternate air outlet as shown in Figure 1.

B) Paragraph A)1 of this AD may be accomplished by the holder of at least a private pilot certificate issued under Part 61 of the Federal Aviation Regulations on any airplane owned or operated by that person. Make the prescribed entry in the aircraft maintenance records, including those airplanes on which it has already been accomplished, indicating compliance with this AD.

C) The airplane may be flown in accordance with FAR 21.197 to a location where paragraph A)2 of this AD may be accomplished.

D) Any equivalent method of compliance with this AD may be used when approved by the Chief, Wichita Aircraft Certification Office, FAA, Room 238, Mid-Continent Airport, Terminal Building No. 2299, Wichita, Kansas 67209; telephone (316) 269-7000.

This amendment becomes effective on April 8, 1982.
 

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Theoretically the air inside the cowl could be cold enough to ice the tip (moisture from engine). I don't know how feasible that is though as I have no idea what temp rise air usually sees going through the cylinders. I can confirm though that on a 172 I have built up frothy icy oil on the breather. Looked almost like thick boogers.

Exactly what I'm trying to understand - can air coming out of the cowl really be below freezing after going through the cylinders? I'd guess with CHTs over 300F the air flowing out would be above freezing. If the breather is out in the airstream, as I have seen with some aircraft, perhaps it can freeze - but totally in the cowl? Seems like it would stay above freezing, but clearly this breather tube icing has happened, which is why we need to cut the "ice hole". I'm sure I'm missing something obvious, but it's not yet obvious to me.
 
Jereme
What size hole did you drill?
Which way did you bend the hole with the bit? Up or down?

Larry, I used a 1/4" bit. Pull the bit up. It will pivot in the hole and deform the top inward and the bottom outward so that no oil can get out. Unless the bottom is being pressurized but that is another topic for breather tubes.

Exactly what I'm trying to understand - can air coming out of the cowl really be below freezing after going through the cylinders? I'd guess with CHTs over 300F the air flowing out would be above freezing. If the breather is out in the airstream, as I have seen with some aircraft, perhaps it can freeze - but totally in the cowl? Seems like it would stay above freezing, but clearly this breather tube icing has happened, which is why we need to cut the "ice hole". I'm sure I'm missing something obvious, but it's not yet obvious to me.

Ya it sounds unlikely to me too but I simply don't know how much temp the air rises after passing through cylinders. I'm betting it at times it isn't enough to get above freezing; especially if you have OAT like we did a few days ago. Might be fun to stick a temp probe in there one of these days to see what kind of rise it is.
 
Breather tube

First thing I did was straighten out the upper bend. What the heck is Vans thinking. I ordered a 5/8" Power Steering hose with a 90. The hose can be removed to clear the area for maintenance.
Straightening was easy. I filled the tube with sand and just pushed down on the bench. Last bit required a little dead blow work. No damage to the tube. Dump the sand. Wash it out. Good to go.
 
Definitely use a hose that it oil rated---even oil droplets. Yes, heater hose is inexpensive, and easy to change at regular intervals. Most all auto parts stores have a variety---and most will let you go take a look, and pic out one you want.

We use a convoluted teflon hose for this. Bends well, oil resistant. Yes, kinda expensive, but never needs replacing. Have done them for the 5/8 nipples, and the 1 inch nipples on the 540s.

YES----add whistle slots, or a hole (or holes) in the actual breather tube for safety.

Tom
 

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Crankcase breather

My solution worked out very nice. I think.
1. Straighten the upper bend in the aluminum vent tube. Fill it with dry sand and push down on the bench. Dump the sand and wash it out.
2. I used this hose. It's a power steering return hose so oil isn't a problem. Easy to trim and fits perfect. I ordered an extra for the parts supply.
3. Secure the tube to the firewall with Adel clamps and spacers.
Now I can remove the hose to gain access to the area if necessary without messing with the aluminum tube.
Sorry. I don't know how to attach a vertical photo. Tilt your head. :D
20230104_152105.jpg
 
My solution worked out very nice. I think.
1. Straighten the upper bend in the aluminum vent tube. Fill it with dry sand and push down on the bench. Dump the sand and wash it out.
2. I used this hose. It's a power steering return hose so oil isn't a problem. Easy to trim and fits perfect. I ordered an extra for the parts supply.
3. Secure the tube to the firewall with Adel clamps and spacers.
Now I can remove the hose to gain access to the area if necessary without messing with the aluminum tube.
Sorry. I don't know how to attach a vertical photo. Tilt your head. :D
View attachment 36150

Vertical Photo
:)
 

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One more way to do this, I replaced the Lycoming supplied fitting with a 1/2" NPT to -12 AN flare fitting. I then used a 45 degree AN swivel on the end of my breather hose to get the proper routing. This opens up the possibility of putting a 45, 90, 135, or 180 degree AN fitting to get the breather tube to exit in any direction you want without a super large bend radius required in the "standard" 3/4" hose. Wish I had a better pic, but it helped keep the hose "flat" and get it over to the half raven oil separator without interfering with other lines.
 

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Alternate method

I have adopted a different method to control the breather outflow on my engine by installing an air/oil separator on the firewall.

I have used the original tube and rubber hose supplied by Van's.

I shortened the tube by removing material so that the section remaining was a relatively straighter section.

I cut the rubber hose so I had two pieces remaining for my design. The one at the top has the right angle section and I used a straight piece to connect the tube to the air/oil separator.

It has all clamped together very well and the rubber hose is relatively stiff but still has enough flex to accommodate engine movement.

Click on my photographs below.

https://flic.kr/p/2o9ZjhP

https://flic.kr/p/2o9XZta

https://flic.kr/p/2oa18Rx

Regards,
 
I have used the original tube and rubber hose supplied by Van's.

As mentioned/discussed ad nauseum elsewhere on the forums, the Van's provided NAPA Heater Hose, part 9816 or 7545, will not hold up in the presence of oil/combustion byproducts present in the crankcase vent stream and >will< fail over time. It may crack, ooze, etc. which is just a mess, but IIRC there was a possibility of it failing closed which is not a good thing.

Use a rubber hose compatible with oil, gas, etc. MIL-DTL-6000D is the hose of choice. Others have found power steering hoses which are also suitable.
 
Education

Hi Brian,

Thank you for your post and for furthering my education and understanding, you are never too old to learn.

I must admit, until Larry started this post, I was not aware that there was a problem with the hose suppled by Van's. Obviously, I have not been reading the related posts that have detailed this issue.

In my innocence (or ignorance) I simply assumed that if Van's was supplying the part it must meet the required performance for the function. Now that I am aware I will monitor it carefully and replace it once it shows any indication of deterioration.

As I am not a fan of the breather spraying oil on the bottom of the fuselage, nor of petroleum products being sprayed onto hot exhaust pipes, I made the decision to install the Air/oil separator.

My installation of the separator is my main reason of putting up my post and to show folks that there is another option to consider for this installation.

Cheers,
 
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