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Tip: Crankcase Vent Tube Elbow

Dan Langhout

Well Known Member
There's been lots of discussion on the forums about the rubber elbow that Van's supplies to connect the crankcase vent fitting on the engine to the aluminum tube that runs down the firewall. Basically, this elbow is a NAPA 9816 formed 90 degree heater bypass hose for some car or truck. The problem is that since it is a coolant hose, it doesn't stand up well to oil vapor in our application and turns gummy after a while. Proper MIL spec hose is available - but not in a formed 90 degree elbow which is what you need to hook up to the aluminum tube from Van's. What's really needed is a 3/4" diameter formed 90 degree Positive Crankcase Ventilation (PCV) hose.

After digging around quite a bit, with no luck, I finally ran across this:

4QY7cGgvLCDJBUhtYI4RyazoRt319QvJcFo2jjFKi4_Joyet8LxxdsTcm5ZOYwnSyYRjBFrPM2QPbL-U_eHRE4dAIUwbU0edaITU_TfQJIsqIsbGU21jR3zWRoMfmaBr-Po3NAJOrJ3C42NGnEvrB108V3oKjcXJwXj5TfnoPbyESibjjsgq4oYR82ExH1Wjo4mx3UoQzSufp-zuB5_cbJIxQTAYmAyJyb9_vJpZn0HWtjP1U4FnmV53qaWnCXzASAAcC52uxvgx627uIPliyRa1HtQar8_QL9SaVJpd-PeFp9mCIEo9sfbBxSeJLA_IEU2FjmZ298uQo1xAQrb-E1utg2IuVOQHpUbCGWf1-w3OCYvDdav7t_jdQFJcsplnRwKhlMBrXMtaPBWeXbQ5JQB9J_uw0cfsmeeT9pJERK-LvVw0fL29c4J-NjwiFBhloi-m9QnZBSPjf1mI3PwNPiONFysaxalmmgVYx8HHMxYAvOB6B7LFdA4glTvotaaH76onuarbc6KB7I1uBVTHvKUkNCzJ-HiC_5IyCxYkKqssvKQ9bWcrnMfHcS_lbtgqkz1GSCkL_v1G0QQvFMLJ9Q2K9i8d2k7XTuwVSHHGSbxxrz1eHMv80xSlzWbhyiviZCoBxOjDS2J8aAkguAILjPBT2GKv8XhwJIXgsVficL9T17uhFztWab48Vby4kVwVcScV69xZkzIpQnjuMwLTBulKQw=w800-h599


Now this hose is more than it seems. There are plenty of places to buy blue silicone coolant hose which looks much like this. They have the same problem as the other coolant hoses - they won't stand up to petroleum products. This hose has a fluorocarbon liner and is specifically rated to be used in systems where oil vapor is in circulation - exactly our application.

h9l6PAo3slU2j-Ol8eu_XOE6-1hYqzjtpMoWuHvgKG3y5XL8bO4p7ZEN-M2Ry1he-Mkpqm-iUlySQS5TrQqa8dpzkzwWylJLCaW92b6k1VXhLLkHip3TlTLQMRmaLaXfB4-n37TLjhT0QjrLqTaFz0WzIbI7Gk7eehicItAP_P1DfOkvA0cvktv1j8knvWIRiapR9ArFVcrHDhSjcPi4bd0PMTetk7rYJT5nf7EqNMsNdcjDUKpKoKRfnKcW_0kAG3TIUihA4iUhUcm53xG0fo4o-0vS54jD1CBk9OTZLJTzY52DFDZ5PuQswQUfDD9gTUzF0yzx2GIA0VERbD-VRp528sa5h-dn8gn1Bpwdyk5RZEaMUo6lh0hYcPZnQshdczCnGO0Xzyl6nLhS8t9LKoqqtHboIySDPtTP_RsqelnQvCZTLA2PIi9-xyW4jTJaqigpiDps-lI4-9GpkhBcRip41zXS6JCSvwcCOKW6p3VzlGP8cUUFGzCo8sbR3y6k33toyMiwQeuTr6xwbMU_6JwQ2kQ35Xbe7VvGeRqxJkhDOw1edW3Za3nSRgt2aqcf41ENXjQpt2UIvu4QV9mrwR2P7TvDSgYJjJ6ZggjcamAPVhA8GIrftth9z7gY7_l-6oN_3LWvxIFCqCE5pU1cl2RYH2Y7l6j5sz78NocmXAUqhXI1f_rrXc8jSNCXmA7lqGlLw_YwDmywjpz9jZi6LrcDPA=w800-h599


Here's a shot of the trimmed down hose installed on my engine. (For the sharp eyed among you - the oil cooler lines in the background of this photo are not real lines - they are mockups for the actual oil cooler hoses which should be coming from SAC today.) ;)

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The formed vent hose is available from Autosiliconehoses.com which is in the UK. The specific part is SFL 090 019 (19mm hose, 90 degree with Fluorocarbon liner).

They may be available from other sources, but this is where I bought mine. They aren't cheap and with VAT and shipping from the UK it makes it even higher (I bought two and the total was $62.93 - of which almost half was shipping and tax.) However, I don't expect to have to change this thing anytime soon (if ever).

FWIW.
 
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Another solution

A while back I actually looked at using that same hose you found. Seems like it could work well. But I came up with a different solution to the same problem. My solution, in short, was to replace the straight nipple fitting on the engine with a 45 degree nipple fitting. Then use a straight section of MIL6000D hose, no hose elbow needed, to connect to the aluminum tube trimmed a little further away. Makes a neat and secure installation, and uses all appropriately rated standard aircraft materials, which in this case are also actually less expensive and more readily available than that exotic automotive hose elbow.

More details here: http://www.kalinskyconsulting.com/rvproj/crankcasebreather.htm

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My YIO-360-M1B from Lycoming came with the fitting already installed that Roee shows.
I did the same solution. Short MIL6000D.
 
Dan, good find. While the 45 degree fitting might be the best solution, it certainly isn't for an engine already hung! I ended up soldering a couple of copper fittings together to make a 180 degree turnaround, since my breather needed to go down to the right side of the firewall.
 
I like that blue hose Dan. I am thinking of getting one in time for condition inspection. Mine is stock, a bit oversized and doesn't look pretty.
 
Style

I like that blue hose Dan. I am thinking of getting one in time for condition inspection. Mine is stock, a bit oversized and doesn't look pretty.


The real reason I got this hose is because it matches my shoes. ;)
 
safety ALERT!!!

Dan, is that a hose clamp holding on your oil line? If so please change this before flying this aircraft! Please contact me if you have any questions!!! Thank you!
 
Dan, is that a hose clamp holding on your oil line? If so please change this before flying this aircraft! Please contact me if you have any questions!!! Thank you!

Read his whole initial post - he specifically say that those are mocked-up oil lines....
 
I used a hose from Samco that is bent through 135*, still has the lining that allows it to resist oil.

I know this isn't an RV, but the installation in the RV is similar.

BlueHose.jpg
 
The blue silicone hose is fine for oil breather hose. Standard heater hose is not. Ive sent some convoluted stainless teflon to some of you for the ultimate in breather assemblies. Bends pretty easy even in larger sizes. Ive been working on some applications with AN hose ends. Takes some doing, but looks good. A few growing pains, and getting things married up, but essentually if you want a straight, 45* or 90* hose end to match a AN816 nipple (or equivelant) of the size of your choice, this can happen. Down side is the costs. Get alittle pricey, but for guys with inverted oil systems, I think its a good system. MUCH better than heater hose and hose clamps.
Tom
 
The fellow that helped me with my breather hose assembly told me to route the hose slightly upward before going down the firewall and I would have much less oil mess on the belly of the plane. He was right. I have 70 hours on the plane and have only cleaned the belly once. There was only a slight stickyness to wipe off and no visible oil.
 
Yes, it can be done with the engine already hung

While the 45 degree fitting might be the best solution, it certainly isn't for an engine already hung!

It certainly is! I swapped out my fitting with the engine already hung. There was still just enough clearance around the engine mount to be able do it, just barely.
 
What I try to avoid is anything in the way of doing normal maintenance. That includes anything going from the motor to the firewall in the area of the mags and the oil filter. I found no need for the aluminum tube mounted to the firewall, and ran my vent close to the back of the motor down to the exhaust.

I used clear poly tubing from ACE and secured it with a double wrap pull tie.... It's only a vent, don't make it complicated. That is a brass fitting from ACE. And yes, the adel clamp is holding a copper pipe coupling. Prefect fit.
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