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  #111  
Old 07-10-2014, 03:32 PM
Toobuilder's Avatar
Toobuilder Toobuilder is offline
 
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Quote:
Originally Posted by Bill.Peyton View Post
Mike,
It's not the valve that's coking up, it's the outlet of the spigot at the exhaust...

OK, I get the coking of the pipe - I thought Vic was seeing the valve itself clogging...

The point remains however, these valves don't see much temperature for the automotive AIR system they are used on/designed for - at least compared to hours of glowing red aircraft pipes we have. I wonder if relocating them to the engine end of the hose would be of benefit?
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1984 L39C

Last edited by Toobuilder : 07-10-2014 at 03:45 PM.
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  #112  
Old 07-10-2014, 04:14 PM
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DanH DanH is offline
 
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Are we satisfied that all coked taps were installed in a tailpipe? No coked tap was installed in a headpipe, or in a collector?

Vic, can you confirm yours was in a tailpipe, downstream of a muffler? Anybody else with mufflers?

Get some temperatures. Nobody can do it but the folks with the problem.

Quote:
Originally Posted by Toobuilder View Post
The point remains however, these valves don't see much temperature for the automotive AIR system they are used on/designed for - at least compared to hours of glowing red aircraft pipes we have. I wonder if relocating them to the engine end of the hose would be of benefit?
Let's not confuse the issue. Don't think anybody has failed a reed valve, at least not a good reed valve.
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Last edited by DanH : 07-10-2014 at 04:27 PM.
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  #113  
Old 07-10-2014, 06:46 PM
vic syracuse vic syracuse is offline
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Default Strong Opinion and advisory

OK, I've been thinking about his all day and have done some research, so I am going to express a much stronger opinion, and I understand that some may not be comfortable with it. I'm OK with that and I'll tell you why.

I believe very much in all of the Experimental aviation we do. However, sometimes there becomes enough data that points to a potential safety problem. I have spent the last year chasing down everything I could thing of that could be wrong with my engine, because others on this board, and even certain suppliers, stated that no one else is having this problem, so it must be me. I had occasion today to get some advice from "old-timers" who claim that this setup was tried 30 years ago by a number of them and they had nothing but coking problems, so they all removed them.

Looking back, I think one of the differences is not with my "setup" but the fact that I fly it A LOT. I fly 200-300 hours per year, and take long trips like this current trip to Alaska, where we will put 50+ hours on it. I believe I am seeing things that ALL of you with this setup are eventually going to experience, and that is coking within 30-50 hours. There are already a few of you in this thread who have reported it.

It is true that we are experimenters, and I also believe the axiom that "we stand on the shoulders of giants." It has become clear to me today that some of the giants have already had bad experiences with this setup.

Here's my concern for those of you running this setup, especially without a safety valve. With a lot of local flying, 1-2 hours at a time, maybe 20-30 hours per years, you won't see this issue rear it's ugly head until you decide to take that long cross-country to OSH, to the Bahama's, or to Alaska, where you will very quickly add the 20-50 hours where the coking WILL show up. Without the safety valve, the odds are you could have a very serious problem before you catch it, including a blown nose seal and the commensurate loss of oil pressure.

No, there is nothing wrong with the valves. There is most likely nothing wrong with the air/oil separator (I don't even have it installed this time. I have duplicated the problem with and without the separator). This is a problem with attaching the output of the breather tube to the exhaust system. And yes, Dan, mine is aft of the muffler on the RV-10.

Against my best judgment I made this change again before a long trip to Alaska. I broke my own rule of no changes at the last minute, but at least Dan's safety valve worked. Someone must be looking out for me. So I feel obligated to pass along the experience and the warning. Please heed them.

Vic
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  #114  
Old 07-10-2014, 07:17 PM
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I'm with Vic, when it comes to aircraft I'm pretty conservative and will "NEVER' be one of the early adopters of untested accessories/components that may effect the operation of the airframe or powerplant.

Just to add an extra 2c here, this mod has been done by many just to keep a little oil off the belly, hardly worth the risk IMO (get a rag and some mineral spirits and clean the belly for petesake, it won't kill you)
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Last edited by Walt : 07-10-2014 at 07:20 PM.
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  #115  
Old 07-10-2014, 08:40 PM
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Toobuilder Toobuilder is offline
 
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It's probably done by most airplane people to keep the belly clean, yes, but the drag racing guys use it for power. So the concept is valid - the execution may be suspect.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

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1984 L39C
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  #116  
Old 07-10-2014, 08:45 PM
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Toobuilder Toobuilder is offline
 
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Quote:
Originally Posted by DanH View Post
...Let's not confuse the issue. Don't think anybody has failed a reed valve, at least not a good reed valve.
I never liked the idea of attaching a valve to a 1000 degree exhaust pipe, but I was willing to run with it until I saw Vic's post about the "coked up valve". Perhaps I took the reference to literally, but do you see any harm in locating the valve in a more favorable operating environment anyway? Certainly we can discuss without "confusing" anyone.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
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1984 L39C
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  #117  
Old 07-10-2014, 09:40 PM
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Quote:
Originally Posted by Toobuilder View Post
...do you see any harm in locating the valve in a more favorable operating environment anyway?
Well, ok....

I have run one in a remote location. It was 1985. Works fine, with a caveat....the trick is attaching the hose to the exhaust pipe. The large diameter spigot allows hot exhaust gas to pulse into the hose, as the hose volume acts like an accumulator. The hose gets hot. Go ahead, give it a try.

Or we can just measure the temperature of the reed valve.....

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  #118  
Old 07-10-2014, 09:46 PM
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ColoRv ColoRv is offline
 
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Quote:
Let's not confuse the issue. Don't think anybody has failed a reed valve, at least not a good reed valve.
My A&P put this setup on his RV4 a long time back (he and Vetterman were experimenting)....valve stuck and blew his front seal out. Wasn't coking in the tube, it was a stuck valve. He couldn't have been more emphatic in his objection to the Antisplat system I have installed (though clearly I didn't listen...it is an experiment I wanted to run). I'll keep a close eye on it.
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Last edited by ColoRv : 07-16-2014 at 06:26 AM.
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  #119  
Old 07-10-2014, 10:42 PM
vic syracuse vic syracuse is offline
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Default This is dangerous

I don't know how much clearer I can be here. This is a dangerous configuration that will eventually bite you. I've clearly demonstrated it twice. Which is exactly 2 more times than I would have liked.

I would not recommend you fly your airplane home without first disconnecting the attachment to the exhaust system.

It could be a valve, but it more likely is the coking. Don't waste your money on another valve unless you are going to put it in the system as a safety valve. It is a very risky proposition otherwise.

I am going back to the Airwolf separator. I have used it on multiple airplanes with never a problem and no oil on the belly. Yes, I know it is more expensive. But it works.

Vic
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  #120  
Old 07-11-2014, 03:07 AM
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C-FAH Q C-FAH Q is offline
 
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Default Double hit

I have had one valve fail, luckily it failed in an open position. I have also had my spigot coke over, which then produced leaks all over the place. I have since disconnected it and will not be hooking it back up. I like the idea of the valve, it just needs to be made fail safe but not sure how that would be done. I think Rocket bob has used a wet vacuum pump to pull a vacuum on the case, that maybe the answer?
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