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Steve Pierce
05-29-2018, 06:57 AM
Was following a Carbon Cub cross country flight on Facebook that was having some engine issues. Was first identified as contaminated fuel system but further flight proved that might not have been the cause. Oil consumption went up rapidly and the engine would miss intermittently. Luckily it was an easy fix. The crankcase vent terminates into the 4 into 1 exhaust pipe and needs to be cleaned out periodically with a round brush. Cub Crafters issued a service instruction on the subject. If you fly a Carbon Cub this is a good one to be familiar with.

http://legacy.cubcrafters.com/technical_publications/74/view

Cub Crafters has a lot of service documents on their website which makes maintaining these airplanes way easier.
http://cubcrafters.com/service-support/publications

spinner2
05-29-2018, 07:45 AM
I like the CC exhaust system but it does have this issue. This venting into the collector keeps the belly very clean.

Mine me got replaced with a Vetterman crossover system quite a while ago and I really like it.

Farmboy
05-29-2018, 09:20 AM
Steve,

So the vent gets plugged, increasing case pressure and causing oil burn rate to increase. What causes the miss, the oil burn?

thanks,
pb

N9PW
05-29-2018, 01:33 PM
Was following a Carbon Cub cross country flight on Facebook that was having some engine issues. Was first identified as contaminated fuel system but further flight proved that might not have been the cause. Oil consumption went up rapidly and the engine would miss intermittently. Luckily it was an easy fix. The crankcase vent terminates into the 4 into 1 exhaust pipe and needs to be cleaned out periodically with a round brush. Cub Crafters issued a service instruction on the subject. If you fly a Carbon Cub this is a good one to be familiar with.

http://legacy.cubcrafters.com/technical_publications/74/view

Cub Crafters has a lot of service documents on their website which makes maintaining these airplanes way easier.
http://cubcrafters.com/service-support/publications

I use a rifle cleaning rod with a .45cal bore brush. Punch the bore with every oil change.


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cubdriver2
05-29-2018, 01:36 PM
Steve,

So the vent gets plugged, increasing case pressure and causing oil burn rate to increase.

thanks,
pb

Even quicker if you have a smoke system

Glenn

bob turner
05-29-2018, 10:24 PM
That is good info.

Just the normal crankcase breather needs cleaning once in a while. What is in there looks a lot like what an abandoned outhouse looks like - or a jet outflow valve back in the smoking days!

Scouter
05-30-2018, 07:22 AM
Upon the advice of Mr Pierce-of the Texas Pierces, I stuck my head anda flashlight in he exaust stack of Mr CarbonCub
Crank vent tube was nearly closed off with carbon crap
Excellent advice. Thx
jim

mike mcs repair
05-30-2018, 12:32 PM
guess you won't have a frozen breather....either...

mvivion
05-30-2018, 12:37 PM
I think if it were me, I’d rearrange that breather setup. Seems like a problem waiting to happen. Stick the end of the breather in a bottle if you can’t stand a bit of oil on the belly.

MTV

DENNY
05-30-2018, 10:59 PM
It should still have a whistle slot in the tube, even when vented to exhaust. I saw a CC recently at Valdez and was wondering why I did not see one.
DENNY

DENNY
05-30-2018, 11:03 PM
Venting exhaust into the intake is a old hot rod trick. It is supposed to seal the rings better by using venturi effect to add suction to crankcase. Lucky he did not blow front seal.
DENNY

Steve Pierce
05-31-2018, 06:45 AM
Works very well. Simple procedure at oil change and can be cleaned with the cowl on. Just needs to be done.

willyb
06-01-2018, 05:57 AM
We used one way check valve at header collector.Valve was from the AIR system (smog pump).It prevents reversion backflow into breather line.
KB

PerryB
06-01-2018, 06:34 AM
I don't think reversion is an issue. The line is getting plugged due to coking and the engine can't get rid of it's own blow-by.

cubdriver2
06-01-2018, 09:06 AM
We used one way check valve at header collector.Valve was from the AIR system (smog pump).It prevents reversion backflow into breather line.
KB

A PCV valve?

Glenn

PerryB
06-01-2018, 11:38 AM
He's talking about a check valve like you'd find on the air injection hose (smog pump hose) between the air pump and the exhaust manifold on a 70's - 80's era vehicle. Usually about a 3/4" line.

WilgaBeast
06-10-2018, 12:00 PM
Steve P is a true lifesaver.

I did have a gas contamination issue which caused the initial rough running situation.

Timing just worked out that I also had the clogged vent.

So grateful for the SuperCub community to get me back in the air. Steve (SuperCub.org) and Steve P, I cannot thank you enough.


Hereís the video log I made of the trip. Iíll further explain in a future release. (Doing these videos takes a little time!!)

https://goo.gl/F3uo5u

~ Cory Robin



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