Crankcase Vent Fitting and Breather Tube

[Glen Geller]

Hi Folks,
Just got back from the hangar and forgot to check other planes for correct type/thickness of 5/8" O.D. aluminum tubing for the crankcase & vac pump breather down tubes. Can't remember if it's 3003, 6061 or 5052, and what correct wall thickness etc.
I am amending an earlier order from our favorite A/C supply company and want to get it added tonight so it might all ship at once.
I already have the MIL6000D oil hose stock to run from the engine/vac pump/oil separator/aluminum down tubes, but need to order the correct aluminum stuff.
Example: http://www.aircraftspruce.com/catalo...clickkey=57039

Additional issue: The 3/4 breather nipple that sticks from the top/rear of crankcase is loose and spins in the casting, but does not pull out.
This doesn't seem right. Any thoughts on how it should be secured so it's tight in the casting? I'll run it by the A&P but wanted some thoughts from you guys as well.

Thanks as always for your help and advise, it would be impossible to afford a classic plane without a group such as this.

GG

[mmoyle]

Sounds like you'll need to helicoil the crankcase vent NPT hole. 5052, 3003 aluminum will work as a replacement for the crank case vent tube. One thing to do is add an additional vent system in the crank case tube. This vent is for allowing the crank case to vent if the crank case vent in the air stream freezes shut. To do this use a hack saw or band saw to slice 1/4 the diameter of the crank case vent tube near the exhaust. On the up stream side of the cut punch the tube in to create a reverse type louvre. This will prevent pushing engine oil past the rings....frying you engine in flight....if the crank case vent tube freezes shut where it sticks out into the air stream.
Mark M.


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[Steve Pierce]

I use 5052 because 3003 comes in a coil and is not very rigid. I also use 3/4". The vent nipple in the accessory case is swedged in in most cases. The crankcase shops (Divco, Crankcases Services) will probably rent you the tool to re-swedge.

[Glen Geller]

Thanks Guys, I appreciate the help. And yes I know about the whistle hole in the crankcase breather tube.
I'll talk to the IA about swaging that tube back into the crankcase.

A/C Spruce order updated!

GG

[LightFlight]

Thanks Guys, I appreciate the help. And yes I know about the whistle hole in the crankcase breather tube.
I'll talk to the IA about swaging that tube back into the crankcase.

A/C Spruce order updated!

GG

I need to order this next pay as well. Excellent timing for this thread! I am adding an air/oil separator to keep the belly clean and need to re-route.

To run above the cylinders to behind the baffle, would aluminum or oil hose be more appropriate?

We were thinking aluminum.

If no bends, why not use 6061 over 5052? Would be more rigid?

Cheers,

Joel

[mmoyle]

Just checked the crank case vent on my narrow deck 320. NPT on the lower right side of the accessory case. The O-290 has the swaged fitting... I think it's sitting out in the cold hanger all unloved....
Mark M.


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[gliderman]

Joel
I used flexible hose. I removed and pitched the old aluminum one as it was in need of replacement. neat and quick. drilled a hole in the hose for our lovely Canadian winters and the freeze up scenarios.
personal preference I guess

I need to order this next pay as well. Excellent timing for this thread! I am adding an air/oil separator to keep the belly clean and need to re-route.

To run above the cylinders to behind the baffle, would aluminum or oil hose be more appropriate?

We were thinking aluminum.

If no bends, why not use 6061 over 5052? Would be more rigid?

Cheers,

Joel

[halestorm]

Alloy of tube, whatever's cheapest!

Always used 5052-0 myself, soft enough to take a nice bend (once packed with sand) and stiff enough to stay in place. For the whistle hole just drill, step drill for a nice burr free hole in soft material, take a punch and lean it over for the louver effect, boom! Shoot with grey enamel and secure with a couple adel clamps for that OEM look.

[John_McF]

Hi All,

Is there an issue with combining Air Oil Separator tube with Crankcase vent, above the bottom cowl line, so only 1 tube is exiting the cowl?

Or does eveybody just dump these in to the Cowl exit area as two pipes?

Cheers
John

[Steve Pierce]

Is it coming off a wet vacuum pump?