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X- Cub Crank Case Vent

Steve Pierce

Steve Pierce

BENEFACTOR
Graham, TX
Just did an oil change on an X Cub with 74 hours on the tach. Looking around I noticed that the crankcase vent goes into the center of the 4 into 1 exhaust pipe like the Carbon Cubs so I looked up the tail pipe and it had about a 1/4" of opening left. I should have gotten a picture but didn't. Cleaned it out and sent them on their way. Looked on Cub Crafters website but didn't see any service documents referring to this procedure but that it a good idea to clean it at every oil change like on the Carbon Cubs. Just a heads up so someone doesn't have an issue.

http://legacy.cubcrafters.com/technical_publications/74/view
 
Steve, This is the second time that you have mentioned this situation. As good an idea as this seems to be for clean bellies, I am of the opinion that its a set up for an accident for some who may be unaware. For example pilots who do not do their own maintenance while depending on a busy mechanic. What happens when someone goes on an extended trip and this doesn't get cleaned out?
 
skywagon8a said:
Steve, This is the second time that you have mentioned this situation. As good an idea as this seems to be for clean bellies, I am of the opinion that its a set up for an accident for some who may be unaware. For example pilots who do not do their own maintenance while depending on a busy mechanic. What happens when someone goes on an extended trip and this doesn't get cleaned out?
Click to expand...

That is why I keep posting about it. Word needs to get out. Aerobatic guys been doing it without the clogging issues for years. Might need to re-engineer it.
 
Have seen the same issue on a SQ-2- #8 nipple welded to the exhaust. Kept chasing an oil leak that looked a lot like the crank seal, until the owner mentioned that the seal had blown out once before when that fitting clogged at the exhaust. Pulled the line off at the fitting, and sure enough- barely a pinhole remaining. Cleaned it out and no more oil leak. A great idea to keep the belly clean, but it does need frequent attention; I think I’d check it at every oil change...
 
Is there a whistle hole higher up in the vent? That may solve the coking problem and if not, it would serve as a safety in the event of a blockage.
 
More sharing from Mike. His imagination for solving problems never ceases to amaze. The same is true for his willingness to share.
 
stewartb said:
More sharing from Mike. His imagination for solving problems never ceases to amaze. The same is true for his willingness to share.
Click to expand...

I feel bad that it been along time since I made a new video to show how to do a task... sure wish others would also take the time to video and show how they do their tasks, so I might learn a new way too....
 
I doubt the X Cub has the whistle slot. Will have to look next time I am around it. Quite a few similarities to the Carbon Cub firewall forward except the engine model.
 
Steve Pierce said:
I doubt the X Cub has the whistle slot. Will have to look next time I am around it. Quite a few similarities to the Carbon Cub firewall forward except the engine model.
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EVERY crankcase vent should have an auxiliary vent, or “whistle slot”. This system just looks like a setup for failure, with little benefit.

MTV
 
Steve Pierce said:
I doubt the X Cub has the whistle slot. Will have to look next time I am around it. Quite a few similarities to the Carbon Cub firewall forward except the engine model.
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Steve,

Does the X Cub have the pressure relief hole ?

thanks,

Jonny
 
Tom Ford's advise to use a .45 cal bore brush works slick. CC recommendation at oil change.
 
Thanks for posting this Steve! I have just completed 100 hrs on my EX-2 and did a mini annual, checking everything I could see or touch. But would have never considered looking up the exhaust at the oil breather tube exit. Mine was not clogged but, I'm guessing here, a 50% reduced opening. The plane does not spew a lot of oil as I have figured out the proper amount of oil for the plane. Put a .45 cal bush on the end of a cleaning rod and brushed out a lot of gunk.

I cannot find in the Maintenance Manual where it states to check this.
 
aeroaddict said:
Thanks for posting this Steve! I have just completed 100 hrs on my EX-2 and did a mini annual, checking everything I could see or touch. But would have never considered looking up the exhaust at the oil breather tube exit. Mine was not clogged but, I'm guessing here, a 50% reduced opening. The plane does not spew a lot of oil as I have figured out the proper amount of oil for the plane. Put a .45 cal bush on the end of a cleaning rod and brushed out a lot of gunk.

I cannot find in the Maintenance Manual where it states to check this.
Click to expand...

http://cubcrafters.com/c/wp-content/...Tube_Rev_A.pdf
 
I would look at all the service letters, instructions etc on Cub Crafters website. There are quite a few depending on serial number.
 
The idea of the breather being plumbed into the center of the four exhaust tubes is that the exhaust flow would generate a vacuum there and so also in the crankcase. The lower pressure in the crankcase is supposed to reduce oil leaks and, yes, increase power. NASCAR teams use a vacuum pump to do this. So, of course there is no whistle slot.

I have no evidence that this works, just throwing out the idea.

john
 
Crankcase vacuum isn't a new idea but without a thermacter valve that vent can't maintain vacuum. Look at Anti Splat Aero's website for their crankcase vacuum kit. It works best with their oil separator but some guys leave the separator off and some leave the thermacter off and just use the tailpipe fitting. Google crankcase vacuum and you'll find lots of info from several sources including Moroso. It works.

https://antisplataero.com/products/crankcase-vacuum-kit-complete
 
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