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breather pipe suggestions?

scsmith

Well Known Member
I have an aluminum 5/8" diameter breather pipe running down my firewall, perfectly bent to terminate just above the exhaust pipe, just how I like it.

The engine breather fitting is a 3/4" tube fitting on the accessory case.

I have a 3/4" i.d. to 5/8" i.d molded rubber elbow on that fitting, then a short section of aluminum tube, then a 5/8" molded rubber elbow that connects to the aluminum tube running down my firewall. All is great, except.....

The two molded rubber elbows are heater hose, not PCV/emissions hose. They are not very resistant to oil. So after a few years, they are kind of swollen and sweat oil on the outside a little bit. So I have just been changing them every couple of years.

But wouldn't it be nice if I could find molded rubber elbows in PCV hose (not to be confused with PVC ;) ) that was the right size?

Ideas?

I'm more than a little reluctant to change the tube fitting on the engine, it is a very lightweight fitting, and it was installed into the accessory case when the engine was first built, probably before humans walked on the moon. My hunch is that if I put a socket on that fitting and try to unscrew it, it will rumble and buckle into a mess.


Does anyone know the I.D. of the molded hose that Van's sells for breathers? If it is 5/8", that would at least solve half my problem.
 
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stick with 3/4 until the line reaches an apex as high as possible (without hitting the upper cowl, of course), then neck down to 5/8. This allows oil mist to drop out of the flow during low velocity, and gravity feed back toward the engine.
I made a reducer using a piece of 3/4 copper, a 3/4 to 5/8 sweat reducer, and a stub of 5/8 copper, then coupled up with short chunks of MIL 6000D hose
 
stick with 3/4 until the line reaches an apex as high as possible (without hitting the upper cowl, of course), then neck down to 5/8. This allows oil mist to drop out of the flow during low velocity, and gravity feed back toward the engine.
I made a reducer using a piece of 3/4 copper, a 3/4 to 5/8 sweat reducer, and a stub of 5/8 copper, then coupled up with short chunks of MIL 6000D hose

That doesn't really help solve the issue of the 90-degree elbows
 
The way I did this, was to use a 3/4 ID hose to go to a 3/4 OD aluminum tube. The 3/4" hose was long enough to make a 180 to the firewall and then a 90 down to the aluminum tube. This made of a nicer and perhaps less restrictive turns.
 
What about this Steve ?

Make an elbow form out of foam sealed with West 105. Wrap it with Dan’s Ultra Black impregnated glass tape as thick as you like. Pour in the Acetone and install ��
 
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Try premolded silicone 90* hose. Or, we did this for a client. Convoluted teflon, impervious to oil, and has pretty good flexibility. He wanted just enough to connect to his aluminum tube. 3/4 ID, so he had to expand the aluminum tube on the hose end to fit tight, then clamp. Think he wrapped it with firesleeve tape, ot maybe took a piece of 3/4 OD, .049 wall aluminum tube and forced it over the breather tube to "enlarge" the end to fit the hose.

Bullet proof, and oil doesnt affect it.

Tom
 

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I had a similar challenge on the 10. I used silicone hose to get to the down tube, but couldn't find the elbows I needed (can't get much bending in that type of hose) I used a bit of 3/4" copper tube and elbows, soldered up to match the angles I needed. In your case, 1/2" copper tube should have an OD around 5/8", so just solder a small stub of tubing on each end of the elbow for the transition to rubber or silicone. A street elbow will only require one stub. It adds a couple ounces of weight, but avoids a hassle. Type M is lighter than L or K.

You can also find pre molded elbows in silicone at the race shops, like summit. Not sure you will find 5/8 ID though.

Larry
 
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Try going to your local Napa or equivalent auto parts store and ask if you can look through their stock of pre-molded tubes ... you might be able to find one with a 90 deg turn and the correct (different) ID's somewhere along it's length .. just cut to fit.

I had a friend in college with a Saab 900, which he was fiercely proud of. While on a road trip to a wedding, one of the rubber cooling tubes sprung a leak, a small elbow with different IDs on each end. We were stuck in Deming NM; the guy at the Napa shop chuckled when we asked if they had a spare and said that the nearest Saab dealership was in Phoenix. I tried the tube search trick, and found a perfect replacement in the middle of a tube for some type of Chevrolet.

From that day forward, the Saab was always referred to as "The Chevy".
 
I used MIL6000D hose to run from the breather, up over one of the motor mount truss work and then down the firewall -- about the same location as the stock aluminum tube with adel clamps at strategic places along the firewall. At the exit point, I installed a piece of aluminum tube (3/4" IIRC) and positioned it about 1/2" or so from the exhaust pipe. It's the same diameter as the breather nipple from end to end -- possibly better flow characteristics.
 
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Try premolded silicone 90* hose. Or, we did this for a client. Convoluted teflon, impervious to oil, and has pretty good flexibility. He wanted just enough to connect to his aluminum tube. 3/4 ID, so he had to expand the aluminum tube on the hose end to fit tight, then clamp. Think he wrapped it with firesleeve tape, ot maybe took a piece of 3/4 OD, .049 wall aluminum tube and forced it over the breather tube to "enlarge" the end to fit the hose.

Bullet proof, and oil doesnt affect it.

Tom

Hey - I think I recognize that!! :)

The heavy black “wrap” is actually thick heat-shrink tubing that was handy. Diameter adjustments might have been made with various wrap material that passed temperature tests…..
 
Hi Paul----I thought you would!!!

Bill----any pre molded hose from Napa or others would be heater hose and NOT oil or oil spray compatible. It will become soft like a sponge.
Now, industrial and truck supply houses 'may' have something, but probably not in a 3/4 ID.

We have also replaced the accessory case nipple to use a AN816 and a AN hose end on the breather side, especially with Christen/Raven inverted oil systems.

Tom
 
I had a similar challenge on the 10. I used silicone hose to get to the down tube, but couldn't find the elbows I needed (can't get much bending in that type of hose) I used a bit of 3/4" copper tube and elbows, soldered up to match the angles I needed. In your case, 1/2" copper tube should have an OD around 5/8", so just solder a small stub of tubing on each end of the elbow for the transition to rubber or silicone. A street elbow will only require one stub. It adds a couple ounces of weight, but avoids a hassle. Type M is lighter than L or K.

You can also find pre molded elbows in silicone at the race shops, like summit. Not sure you will find 5/8 ID though.

Larry

Pegasus Auto Racing and Summit both have molded silicone hoses that are perfect for what I need. But they say in the fine print that they are not resistant to oil. I imagine they would be better than heater hose though, so that might be a way to go. Dave Howe sent me a note about a racing shop in the UK that offers silicone hoses with a "flouro" liner that makes them oil resistant. Anyone know anything about that?
 
Yep, florosilicone is oil resistant, but expensive.

You can always byt several of the heater hose versions and change them at conditional time.

Tom
 
I've used Flourosilicone hoses for the first part of the breather for many years. They have to be swapped out after a few years, perhaps 5 or 8.
The most well known company over here is called Samco, but several others.
This link gives an indication of the relative prices.
Just a little more than twice as expensive as silicone - not too bad for an angle or a short length.
 
An alternative...

I was looking at a friends IO-360-M1B, and I noticed that the breather tube is different than what is installed on my IO-360-A1B6, i.e. an AN844-10D (45° elbow tube 5/8") and I have the "classic" 71140 Breather fitting (3/4").

As we all know, the Van's firewall forward kit breather setup consists of a NAPA 9816 coolant hose (3/4"I.D. 90° elbow) and a piece of 5/8" aluminum tubing with a 3/4" flare on one end that is supposed to mate with the NAPA hose and then the Lycoming 71140.

What if we were to change to an AN844-10D elbow, connect a short length (say 4" - 6") of MIL-DTL-6000D 5/8" hose to the Van's pre-fab tube -- we'd need to cut the flared end off, clamp and go

Thoughts -- in no particular order:

1. Eliminating the NAPA 9816 is a good thing -- rad hose won't stand up to the evil emanations from the crank case.

2. The port in the case for the breather is 1/2" NPT, so changing from 3/4" (71140) to 5/8" (AN844-10D) doesn't restrict anything.

3. AN844-10D is in the parts catalog as a breather option. AN844-10 is also available in brass.

4. See #2 - the Van's tube is 5/8", down stream of the 71140/NAPA 9816 so changing to 5/8" for the length wouldn't present any restriction to the breather operation.

5. MIL-DTL-6000D is designed for all manner of petroleum distillates, is flexible, so engine shake/rattle/roll is handled in much the same way as the NAPA 9816 but without the risk of rot/collapse...

Whatcha think? Attached images from the Lyc. catalog.

B
 

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alternate to van’s breather design

What if we were to change to an AN844-10D elbow, connect a short length (say 4" - 6") of MIL-DTL-6000D 5/8" hose to the Van's pre-fab tube -- we'd need to cut the flared end off, clamp and goB

Exactly what I did on my 6A. Works well with no soft/squishy heater hose after a couple off years. I did have to replace the oil hose after 8 years and 1000 hours…the mil6000 hose to tough stuff, but it does harden with age, eventually.

The only tough part about this solution is finding the AN844-10D elbow in stock, and what it costs. ~$45 for one AN fitting. Sure it is bigger than all of the 1/4 and 3/8” fittings we normally use……but still more “spendy” than I thought it would be.

Also, beg/borrow/or steal the use of a tube beading tool to bead the aluminum tube. Helps keep the hose from leaking.
 
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On RV10 IO-540 I used good quality silicone hose from engine, all the way down to the exhaust pipe where it’s pushed over (and clamped) to a piece of SS Tube that’s welded into the exhaust. (interestingly around two inches up from the exhaust pipe there isn’t enough heat transmission to effect the silicone hose) The hose can be allowed to go as high as possible under the top cowl, and with suitably sited ties this hose handles the 90* bend and then accommodates any deviations needed on the way down to exhaust. So for me I didn’t use the Vans Aly breather pipe (which freed up firewall space) so no need for the bends etc you are needing. This method is now 760 hours, I have replaced the silicone hose once but only because the outside blue had faded a little, and I had enough on hand to replace it. Anyway, just my TCW
 
Back to Steve's original question - I used a 1/2" copper sweat fitting elbow. The 3/4" hose fits and clamps on to make a nice tight turn.
 

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New & Improved Breather

As part of the Condition Inspection work, I decided to "fix" the original Van's design.

I removed the NAPA radiator elbow hose section & the Lycoming 71140 breather nipple. In its place, I installed an AN844-10 in brass, with a short section of MIL-DTL 6000D 5/8" i/d hose. I cut off about 18" from the Van's breather tube and put a very slight flare in the end.

Picture attached -- clamps are not yet installed...

Enjoy.

B
 

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All Hoses

We have a hose store here in Las Vegas called All Hoses. They can make anything and fire-sleeve it also. They stock silicone preformed hoses bent to 90 and 45 degree angles.
 
As part of the Condition Inspection work, I decided to "fix" the original Van's design.

I removed the NAPA radiator elbow hose section & the Lycoming 71140 breather nipple. In its place, I installed an AN844-10 in brass, with a short section of MIL-DTL 6000D 5/8" i/d hose. I cut off about 18" from the Van's breather tube and put a very slight flare in the end.

Picture attached -- clamps are not yet installed...

Enjoy.

B

This would be a really nice way to go.

I am terrified to try to remove my old Lycoming 71140 fitting. It has been in the case for a million years. I think if I try to turn it, it will just crush it.

I'm also not sure I can turn an elbow fitting into the port if I do get the old fitting out. I think there is an engine mount tube or something in the way? I would have to check again.

For the time being, I have installed molded silicon tubes from Summit racing. We'll see how long they last.
 
As part of the Condition Inspection work, I decided to "fix" the original Van's design.

I removed the NAPA radiator elbow hose section & the Lycoming 71140 breather nipple. In its place, I installed an AN844-10 in brass, with a short section of MIL-DTL 6000D 5/8" i/d hose. I cut off about 18" from the Van's breather tube and put a very slight flare in the end.

Picture attached -- clamps are not yet installed...

Enjoy.

B

Save the weight, cost, and extra work and leave the clamps off.

I have been running without clamps since my RV-6 first flew almost 24 years ago and more than 3,500 hobbs / fight hours.

IF the metal breather pipe were to become clogged, the 6000 hose hopefully will slip off before pressure builds up in the crankcase and blows out the front seal.
 
+1 about no clamps. Definitely not needed here, nor wanted.

The hose below would be good for this application: it's power steering reservoir hose made for hot oil under low pressure. Cut as required.
 

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+1 for Summit Racing (or similar).

I needed a 5/8 elbow to connect to my Moroso valve cover breather I use for crank case vent and after a few minutes of searching, found a perfect fit Dorman molded 75 degree "emissions" elbow. The search function is clunky, but once you figure out how to navigate it there is a plethora of products available. Chances are good that they have "exactly" what you are looking for.

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